Airplane Performance and Handling Qualities in Icing Conditions, 44656-44669 [E7-14937]
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Federal Register / Vol. 72, No. 152 / Wednesday, August 8, 2007 / Rules and Regulations
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA–2005–22840; Amendment
No. 25–121]
RIN 2120–AI14
Airplane Performance and Handling
Qualities in Icing Conditions
Federal Aviation
Administration (FAA), DOT.
ACTION: Final rule.
AGENCY:
SUMMARY: This action introduces new
airworthiness standards to evaluate the
performance and handling
characteristics of transport category
airplanes in icing conditions. This
action will improve the level of safety
for new airplane designs when
operating in icing conditions, and
harmonizes the U.S. and European
airworthiness standards for flight in
icing conditions.
DATES: This final rule becomes effective
October 9, 2007.
FOR FURTHER INFORMATION CONTACT: Don
Stimson, FAA, Airplane & Flight Crew
Interface Branch, ANM–111, Transport
Airplane Directorate, Aircraft
Certification Service, 1601 Lind Avenue
SW., Renton, Washington 98057–3356;
telephone: (425) 227–1129; fax: (425)
227–1149, e-mail: don.stimson@faa.gov.
SUPPLEMENTARY INFORMATION:
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Authority for This Rulemaking
The FAA’s authority to issue rules
regarding aviation safety is found in
Title 49 of the United States Code.
Subtitle I, Section 106 describes the
authority of the FAA Administrator.
Subtitle VII, Aviation Programs,
describes in more detail the scope of the
agency’s authority.
This rulemaking is promulgated
under the authority described in
Subtitle VII, Part A, Subpart III, Section
44701, ‘‘General requirements.’’ Under
that section, the FAA is charged with
promoting safe flight of civil aircraft in
air commerce by prescribing minimum
standards required in the interest of
safety for the design and performance of
aircraft. This regulation is within the
scope of that authority because it
prescribes new safety standards for the
design of transport category airplanes.
I. Background
A. Statement of the Problem
Currently, § 25.1419, ‘‘Ice protection,’’
requires transport category airplanes
with approved ice protection features be
capable of operating safely within the
icing conditions identified in appendix
C of part 25. This section requires
applicants to perform flight testing and
conduct analyses to make this
determination. Section 25.1419 only
requires an applicant to demonstrate
that the airplane can operate safely in
icing conditions if the applicant is
seeking to certificate ice protection
features.
Although an airplane’s performance
capability and handling qualities are
important in determining whether an
airplane can operate safely, part 25 does
not have specific requirements on
airplane performance or handling
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qualities for flight in icing conditions. In
addition, the FAA does not have a
standard set of criteria defining what
airplane performance capability and
handling qualities are needed to be able
to operate safely in icing conditions.
Finally, § 25.1419 fails to address
certification approval for flight in icing
conditions for airplanes without ice
protection features.
Service history shows that flight in
icing conditions may be a safety risk for
transport category airplanes. We found
nine accidents since 1983 in the
National Transportation Safety Board’s
accident database that may have been
prevented if this rule had been in effect.
In evaluating the potential for this
rulemaking to avoid future accidents,
we considered only past accidents
involving tailplane stall or potential
airframe ice accretion effects on drag or
controllability. We did not consider
accidents related to ground deicing
since this amendment does not change
the ground deicing requirements. We
also limited our search to accidents
involving aircraft certificated to the
icing standards of part 25 (or its
predecessor).
B. NTSB Recommendations
This amendment addresses the
following National Transportation
Safety Board (NTSB) safety
recommendations related to airframe
icing:1
1. NTSB Safety Recommendation A–
91–087 2 recommended requiring flight
tests where ice is accumulated in those
cruise and approach flap configurations
in which extensive exposure to icing
conditions can be expected, and
requiring subsequent changes in
configuration to include landing flaps.
This safety recommendation resulted
from an accident that was attributed to
tailplane stall due to ice contamination.
This amendment requires applicants
to investigate the susceptibility of
airplanes to ice-contaminated tailplane
stall during airworthiness certification.
An accompanying Advisory Circular
(AC) will provide detailed guidance on
acceptable means of compliance,
including flight tests in icing conditions
where the airplane’s configuration is
changed from flaps and landing gear
retracted to flaps and landing gear in the
landing position.
1 Refer to appendix 3 of the NPRM for more
details on these safety recommendations (except for
A–96–056, which was not discussed in the NPRM).
2 ‘‘Effect of Ice on Aircraft Handling
Characteristics (1984 Trials),’’ Jetstream 31—G–
JSSD, British Aerospace Flight Test Report
FTR.177/JM, dated May 13, 1985.
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2. NTSB Safety Recommendation A–
96–056 3 recommended revising the
icing certification testing regulation to
ensure that airplanes are properly tested
for all conditions in which they are
authorized to operate, or are otherwise
shown to be capable of safe flight into
such conditions. Additionally, if safe
operations cannot be demonstrated by
the manufacturer, operational
limitations should be imposed to
prohibit flight in such conditions and
flightcrews should be provided with the
means to positively determine when
they are in icing conditions that exceed
the limits for aircraft certification.
This amendment partially addresses
safety recommendation A–96–056 by
revising the certification standards to
ensure that transport category airplanes
are properly tested for the critical icing
conditions defined in appendix C of
part 25. We are considering future
rulemaking action to address icing
conditions beyond those covered by
appendix C of part 25, and to provide
flightcrews with a means to positively
determine when they are in icing
conditions that exceed the limits for
aircraft certification.
3. NTSB Safety Recommendation A–
98–094 4 recommended that
manufacturers of all turbine-engine
driven airplanes (including the EMB–
120) provide minimum maneuvering
airspeed information for all airplane
configurations, phases, and conditions
of flight (icing and non-icing
conditions). Also, the NTSB
recommended that minimum airspeeds
should take into consideration the
effects of various types, amounts, and
locations of ice accumulations,
including thin amounts of very rough
ice, ice accumulated in supercooled
large droplet icing conditions, and
tailplane icing.
This amendment partially addresses
safety recommendation A–98–094 by
requiring the same maneuvering
capability requirements at the minimum
operating speeds in the most critical
icing conditions defined in appendix C
of part 25 as are currently required in
non-icing conditions. We are
considering future rulemaking action to
3 National Transportation Safety Board, 1996. ‘‘InFlight Icing Encounter and Loss of Control,
Simmons Airlines, d.b.a.American Eagle Flight
4184, Avions de Transport Regional (ATR) Model
72–212, N401AM, Roselawn, Indiana, October 31,
1994.’’ Aircraft Accident Report NTSB/AAR–96/01.
Washington, DC.
4 National Transportation Safety Board, 1998. ‘‘InFlight Icing Encounter and Uncontrolled Collision
With Terrain, Comair Flight 3272, Embraer EMB–
120RT, N265CA, Monroe, Michigan, January 9,
1997.’’ Aircraft Accident Report NTSB/AR–98/04.
Washington, DC.
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address supercooled large droplet icing
conditions.
4. NTSB Safety Recommendation A–
98–096 is also a result of the same
accident discussed under Safety
Recommendation A–98–094, above. The
NTSB recommended the FAA require,
during type certification, that
manufacturers and operators of all
transport category airplanes certificated
to operate in icing conditions install
stall warning/protection systems that
provide a cockpit warning (aural
warning and/or stick shaker) before the
onset of stall when the airplane is
operating in icing conditions.
This amendment requires adequate
stall warning margin to be shown with
the most critical ice accretion for
transport category airplanes approved to
fly in icing conditions. Except for the
short time before icing conditions are
recognized and the ice protection
system activated, this stall warning
must be provided by the same means as
for non-icing conditions. Although
neither an aural stall warning or stick
shaker is required under this
amendment, all recently certificated
transport category airplanes have used
either a stick shaker or an aural warning
to warn the pilot of an impending stall.
We do not anticipate any future
transport category airplane designs
without a cockpit warning of an
impending stall.
C. Summary of the NPRM
This amendment is based on the
notice of proposed rulemaking (NPRM),
Notice No. 05–10, which was published
in the Federal Register on November 4,
2005 (70 FR 67278). In the NPRM, we
proposed to revise the airworthiness
standards for type certification of
transport category airplanes to add a
comprehensive set of new requirements
for airplane performance and handling
qualities for flight in icing conditions.
We also proposed to add requirements
that define the ice accretion (that is, the
size, shape, location, and texture of the
ice) that must be considered for each
phase of flight.
These changes were proposed to
ensure that minimum operating speeds
determined during certification of all
future transport category airplanes will
provide adequate maneuver capability
in icing conditions for all phases of
flight and all airplane configurations.
They would also harmonize the FAA’s
regulations with those expected to be
adopted by the European Aviation
Safety Agency (EASA). This
harmonization would not only benefit
the aviation industry economically, but
also maintain the necessary high level of
aviation safety.
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II. Discussion of the Final Rule
A. General Summary
Twelve commenters responded to the
NPRM: Four private citizens, Airbus
Industrie (Airbus), the Air Line Pilots
Association (ALPA), The Boeing
Company (Boeing), Dassault Aviation
(Dassault), the General Aviation
Manufacturers Association (GAMA), the
National Transportation Safety Board
(NTSB), Raytheon Aircraft Company
(Raytheon), and the United Kingdom
Civil Aviation Authority (U.K. CAA).
Seven of these commenters explicitly
expressed support for the rule, none
opposed it. Many of the commenters
suggested specific improvements or
clarifications. Summaries of their
comments and our responses (including
explanations of changes to the final rule
in response to the comments) are
provided below.5
1. Engine Bleed Configuration for
Showing Compliance With § 25.119
The proposed § 25.119 would require
applicants to comply with the landing
climb performance requirements in both
icing and non-icing conditions.
Raytheon stated that proposed
§ 25.119(b) is unclear as to whether the
engine bleed configuration for showing
compliance should include bleed
extraction for operation of the airframe
and engine ice protection systems (IPS).
Raytheon pointed out that engine bleed
extraction for operating the airframe and
engine IPS could affect engine
acceleration time, which would affect
the thrust level used for showing
compliance. Raytheon noted that the
means of compliance in the proposed
AC addresses this issue, but
recommended that it be clarified within
the rule.
While we agree that engine bleed
extraction could affect the thrust level
used to show compliance with
§ 25.119(b), we disagree that the rule
needs to be revised to state the bleed
configuration. For flight in icing
conditions, § 25.21(g)(1) requires
compliance to be shown assuming
normal operation of the airplane and its
IPS in accordance with the operating
limitations and operating procedures
established by the applicant and
provided in the Airplane Flight Manual
(AFM). The bleed configuration of the
engines would be part of the AFM
operating procedures that must be used
to show compliance with § 25.119(b). As
noted by Raytheon, the guidance
provided in the AC accompanying this
final rule reminds applicants that the
5 The full text of each commenter’s submission is
available in the Docket.
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engine bleed configuration should be
considered when showing compliance
with the requirements of this final rule.
2. Using the Landing Ice Accretion To
Comply With § 25.121(d)(2)(ii)
Boeing proposed using the landing ice
accretion for showing compliance with
the approach climb gradient
requirement in icing conditions, rather
than the holding ice accretion as
proposed in § 25.121(d)(2)(ii). Boeing
recommended this change to harmonize
with EASA’s proposed rule.
We consider it inappropriate to use
the landing ice accretion for compliance
with § 25.121(d). Section 25.121(d)
specifies the minimum climb capability,
in terms of a climb gradient, that an
airplane must be capable of achieving in
the approach configuration with one
engine inoperative. This requirement
involves the approach phase of flight,
which occurs before entering the
landing phase. Depending on the IPS
design and the procedures for its use,
the landing ice accretion (which is
defined as the ice accretion after exiting
the holding phase and transitioning to
the landing phase) may be smaller than
the holding ice accretion. For example,
there may be a procedure to use the IPS
to remove the ice when transitioning to
the landing phase so that the protected
areas are clear of ice for landing. It
would be inappropriate to allow any
reduction in the ice accretion to be used
for the approach climb gradient (in the
approach phase) resulting from using
the IPS in the landing phase.
We note that neither EASA’s Notice of
Proposed Amendment (NPA) covering
the same icing-related safety issues
(NPA 16/2004) nor our NPRM define an
ice accretion specific to the approach
phase of flight. Both proposals used
holding ice for compliance in icing
conditions because holding ice was
considered to be conservative for this
flight phase. Therefore, we believe that
it is appropriate to define an additional
ice accretion that would be specifically
targeted at the approach phase of flight.
We have added the following definition
as paragraph (a)(5) in part II of appendix
C:
‘‘Approach ice is the critical ice
accretion on the unprotected parts of the
airplane, and any ice accretion on the
protected parts appropriate to normal
IPS operation following exit from the
holding flight phase and transition to
the most critical approach
configuration.’’
Section 25.121(d)(2)(ii) is also revised
to refer to this definition. The definition
of landing ice is revised to be the ice
accretion after exiting from the
approach phase (rather than after the
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holding phase as proposed) and
redesignated as paragraph (a)(6).
Finally, applicants would still have
the option to use a more conservative
ice accretion in accordance with
paragraph (b) of part II of appendix C.
Therefore, applicants would have the
option of using the holding ice accretion
as proposed in the NPRM if it was more
critical than the approach ice accretion.
3. VREF Comparison at Maximum
Landing Weight
Proposed § 25.125(a)(2) would require
landing distances to be determined in
icing conditions if the landing approach
speed, VREF, for icing conditions
exceeds VREF for non-icing conditions
by more than 5 knots calibrated
airspeed. Boeing proposed that the VREF
speed comparison for icing and nonicing conditions in proposed
§ 25.125(a)(2) be made at the maximum
landing weight. This proposal would
harmonize the FAA’s rule with the
expected EASA final rule. Boeing also
stated that the proposed rule was
deficient in that it did not specify the
weight or weights at which this
comparison must be made. The results
of this comparison can depend on the
weight at which the comparison is
made.
We agree that this comparison should
be made at the maximum landing
weight and have revised § 25.125(a)(2)
of the final rule accordingly. We
consider this to be a clarifying change
that will not impose an additional
burden on applicants.
4. Landing Distance in Icing Conditions
As noted in the discussion of the
previous comment, proposed
§ 25.125(a)(2) would require the landing
distance to be determined in icing
conditions if the landing approach
speed, VREF, for icing conditions
exceeds the non-icing VREF by more
than 5 knots calibrated airspeed. An
increase in VREF for icing conditions is
normally caused by an increase in stall
speed in icing conditions because VREF
must be at least 1.23 times the stall
speed.
Raytheon noted that a change in stall
speed is not the only factor that might
affect landing distance in icing
conditions. For example, idle thrust
might be adjusted by an engine control
system designed to maintain sufficient
bleed flow to support the demands of
engine and airframe ice protection.
Also, landing procedures for icing
conditions might be different than for
non-icing conditions. Raytheon
suggested revising proposed
§ 25.125(a)(2) to require that the landing
distance must also be determined in
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icing conditions if the thrust settings or
landing procedures used in icing
conditions would cause an increase in
the landing distance.
One of the primary safety concerns
addressed by proposed § 25.125 is to
maintain a minimum speed margin
above the stall speed for an approach
and landing in icing conditions. This is
achieved by increasing the landing
approach speed (VREF) if ice on the
airplane results in a significant increase
in stall speed. Under proposed
§ 25.125(b)(2)(ii)(B), a significant
increase in stall speed relative to this
requirement is one that results in an
increase in VREF of more than 5 knots
calibrated airspeed, where VREF is not
less than 1.23 times the stall speed.
An increase in VREF will increase the
distance required by the airplane to land
and come to a stop since the airplane
will touch down at a higher speed. A
significant increase in stall speed in the
landing configuration due to ice has a
secondary effect of increasing the
required landing distance. We proposed
in § 25.125(a)(2) that this increase in
landing distance be taken into account.
Proposed § 25.125(a)(2) resulted from
the secondary effect of a significant
increase in stall speed in the landing
configuration due to ice, not to an
evaluation of all of the possible reasons
why the required landing distance may
need to be longer in icing conditions.
The commenter correctly points out that
a longer landing distance may also be
needed if higher thrust settings or
different landing procedures are used in
icing conditions.
In evaluating the potential costs and
effects of the proposed change, we could
not find any existing airplanes where, if
the requirement proposed by the
commenter had been in effect, it would
have required an applicant to determine
a longer landing distance in icing
conditions. In nearly all cases,
applicants have not used different thrust
or power settings or different
procedures for landing in icing
conditions. Airplane manufacturers
indicated that they did not anticipate
this relationship to change for future
designs.
When different thrust or power
settings or procedures have been used
for landing in icing conditions, VREF has
also increased by more than 5 knots. In
these cases, applicants would be
required by the proposed § 25.125(a) to
determine the landing distance for icing
conditions, and existing § 25.101(c) and
(f) require applicants to include the
effects of different power or thrust
settings or landing procedures on this
landing distance.
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Therefore, we see no need to amend
the proposed requirement as
recommended by Raytheon.
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5. Sandpaper Ice Accretion
Proposed appendix C, part II(a)(6)
defined sandpaper ice as a thin, rough
layer of ice. A private citizen notes the
NPRM did not specifically state how
sandpaper ice should be used or
considered in showing compliance with
any of the proposed airplane
performance and handling qualities
requirements. This commenter
suggested amending proposed
§ 25.143(i)(1) to add that if normal
operation of the horizontal tail IPS
allows ice to form on the tail leading
edge, sandpaper ice must also be
considered in determining the critical
ice accretion. (Proposed § 25.143(i)(1)
would require applicants to demonstrate
the airplane is safely controllable, per
the applicable requirements of § 25.143,
with the ice accretion defined in
appendix C that is most critical for the
particular flight phase.)
Appendix C, part II(a) requires
applicants to use the most critical ice
accretion to show compliance with the
applicable subpart B airplane
performance and handling requirements
in icing conditions. The determination
of the most critical ice accretion must
consider the full range of atmospheric
icing conditions of part I of appendix C
as well as the characteristics of the IPS
(per § 25.21(g)(1) and appendix C, part
II(a)). This includes consideration of
thin, rough layers of ice (known as
sandpaper ice) as well as any other type
of ice accretion that may occur in the
applicable atmospheric icing
conditions, taking into account the
operating characteristics of the IPS and
the flight phase.
Since the requirement to use the most
critical ice accretion includes
consideration of sandpaper ice and
sandpaper ice is not referenced
elsewhere in the rule, we have removed
appendix C, part II(a)(6) from the final
rule. The AC that we are issuing along
with this final rule, or shortly thereafter,
provides further information on the use
of sandpaper ice in showing
compliance. (This AC will be available
in the Regulatory Guidance Library
(RGL) when issued.)
6. Critical Ice Accretion for Showing
Compliance With § 25.143(i)(1)
As noted in the discussion of the
previous comment, proposed
§ 25.143(i)(1) would require applicants
to demonstrate the airplane is safely
controllable, per the applicable
requirements of § 25.143, with the ice
accretion defined in appendix C that is
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most critical for the particular flight
phase. Raytheon stated that because ice
accretion before normal system
operation is addressed separately in
§ 25.143(j), the controllability
demonstration required by § 25.143(i)(1)
should be limited to only the most
critical ice accretion defined in
appendix C part II(a) rather than all of
appendix C.
For purposes of the controllability
demonstrations required by
§ 25.143(i)(1), appendix C, parts I and
II(a), (b), (c), and (d) apply. Appendix C,
part II(e) only applies to §§ 25.143(j) and
25.207(h), which are the only subpart B
requirements pertaining to flight in
icing conditions before activation of the
IPS. We acknowledge that this limited
applicability of appendix C, part II(e) is
unclear in the language proposed, and
we have revised the final rule to include
a sentence that specifies this limitation.
7. Pushover Maneuver for IceContaminated Tailplane Stall
Evaluation
Raytheon stated that proposed
§ 25.143(i)(2), which states that a push
force from the pilot must be required
throughout a pushover maneuver down
to zero g or full down elevator, is
inconsistent with allowing a pull force
for recovery from the maneuver.
Raytheon noted that the FAA stated in
the NPRM that a force reversal (that is,
a push force becoming a pull force) is
unacceptable, implying that the pilot
should only be permitted to relax his or
her push force to initiate recovery. The
50-pound limit for recovery in the
proposed § 25.143(i)(2) appears to allow
up to 50 pounds of force reversal to
develop during the maneuver, including
at the initiation of recovery from the
maneuver. Raytheon stated that they
object to the proposed requirement and
continue to support the industry
proposal for the pushover maneuver
submitted to ARAC by the Flight Test
Harmonization Working Group. The
industry proposal specified there must
be no force reversal down to 0.5 g (the
limit of the operational flight envelope)
and a prompt recovery from zero g (or
full down elevator control if zero g
cannot be obtained) with less than 50
pounds of stick force. Raytheon stated
that the 50-pound pull force was not
intended as a limit for the subsequent
pull-up maneuver during recovery from
the push-over test.
The FAA continues to disagree with
the industry proposal, and Raytheon did
not offer any new evidence or rationale
that would lead us to reconsider our
position. As stated in the NPRM,
certification testing and service
experience have shown that testing to
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44659
only 0.5 g is inadequate, considering the
relatively high frequency of
experiencing 0.5 g in operations. Since
the beginning of the 1980s, the practice
of many certification authorities has
been to require testing to lower load
factors. The industry proposal for
determining the acceptability of a
control force reversal (as described in
the NPRM) was subjective and would
have led to inconsistent evaluations.
Requiring a push force to zero g removes
subjectivity in the assessment of the
airplane’s controllability and provides
readily understood criteria of
acceptability. Any lesser standard
would not give confidence that the
problem has been fully addressed.
We do not consider the requirement
for a push force to be needed to reach
zero g, coupled with allowing a pull
force of up to 50 pounds during the
recovery, to be inconsistent with our
position that force reversals are
unacceptable within the normal flight
envelope. The pushover maneuver ends
when zero g is reached (or when full
down elevator is achieved if zero g
cannot be reached). The recovery is a
separate pull-up maneuver, initiated by
the pilot, to regain the original flight
path. It is acceptable for this maneuver
to require a pull force, but the pull force
must not exceed 50 pounds, which is
the maximum pitch force permitted by
the existing § 25.143(c) (renumbered as
§ 25.143(d) by this amendment) for short
term application of force using one
hand. No changes were made.
8. Pushover Maneuver Limited by
Design Features Other Than Elevator
Power
Airbus noted that proposed
§ 25.143(i)(2) would allow the required
pushover maneuver to end before zero
g is reached if the airplane is limited by
elevator power. Airbus commented that
safe design characteristics other than
limited elevator power may also prevent
an aircraft from reaching zero g during
the pushover maneuver (e.g., flight
envelope protections designed into flyby-wire control systems). Airbus
proposed revising the proposed rule to
allow the pushover maneuver to end
before reaching zero g for other safe
design characteristics that prevent
reaching zero g.
We agree with Airbus and have
revised § 25.143(i)(2) to include
consideration of other design
characteristics of the flight control
system that may prevent reaching zero
g in the pushover maneuver.
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9. Pitch Force Requirements During a
Sideslip Maneuver
Raytheon stated that the proposed
requirement for flight in icing
conditions is more stringent than the
requirements applicable to non-icing
conditions. Proposed § 25.143(i)(3)
would require that any changes in force
that the pilot must apply to the pitch
control to maintain speed with
increasing sideslip angle must be
steadily increasing with no force
reversals. Raytheon notes the non-icing
subpart B static lateral-directional
stability requirements of § 25.177 do not
specify that the pitch forces cannot
reverse. For example, a push force at
small sideslip angles that changes to a
pull force as sideslip increases is
acceptable.
Raytheon noted that it would not be
unusual for an airplane to require an
increase in pull force with increasing
sideslip. If the tailplane or a portion of
it developed aerodynamic separation as
sideslip increases, then to maintain 1–
g flight the elevator hinge moment
would require further pull force that
could be sudden or become excessive.
Raytheon notes this undesirable
characteristic would comply with
proposed § 25.143(i)(3).
Raytheon and another commenter (a
private citizen) proposed that the
proposed rule be revised to eliminate
the requirements that the pitch force be
steadily increasing with increasing
sideslip and that there be no reversal.
Instead, these commenters suggested
that the requirement should be limited
to ensuring that there is no abrupt or
uncontrollable pitching tendency.
The FAA agrees with the commenters
that small, gradual changes in the pitch
control force may not be objectionable
or unsafe, and that the proposed
requirement is unnecessarily more
stringent than the requirements for nonicing conditions. The safety concern is
sudden or large pitch force changes that
would be difficult for the pilot to
control. Therefore, we have changed
§ 25.143(i)(3) in the final rule to read as
follows:
‘‘Any changes in force that the pilot
must apply to the pitch control to
maintain speed with increasing sideslip
angle must be steadily increasing with
no force reversals, unless the change in
control force is gradual and easily
controllable by the pilot without using
exceptional piloting skill, alertness, or
strength.’’
Under this new language, abrupt
changes in the control force
characteristic, unless so small as to be
unnoticeable, would not be considered
to meet the requirement that the force be
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steadily increasing. A gradual change in
control force is a change that is not
abrupt and does not have a steep
gradient. It can be easily managed by a
pilot of average skill, alertness, and
strength. Control forces in excess of
those permitted by § 25.143(d) would be
considered excessive.
10. Stall Warning in Icing Conditions
Existing § 25.207(c) requires at least a
3 knot or 3% speed margin between the
stall warning speed (VSW) and the
reference stall speed (VSR). Existing
§ 25.207(d) requires at least a 5 knot or
5% speed margin between VSW and the
speed at which the behavior of the
airplane gives the pilot a clear and
distinctive indication of an acceptable
nature that the airplane is stalled. Under
proposed § 25.21(g), the stall warning
requirements of § 25.207(c) and (d)
would apply only to non-icing
conditions. For icing conditions,
proposed § 25.207(e) requires that stall
warning be sufficient to allow the pilot
to prevent stalling when the pilot starts
the recovery maneuver not less than 3
seconds after the onset of stall warning
in a one knot per second deceleration.
The U.K. CAA noted that proposed
§ 25.207(e) would allow stall warning in
icing conditions to occur at a speed
slower than the speed for the maximum
lift capability of the wing (also known
as the 1g stall speed). This would not be
true for non-icing conditions because of
§ 25.207(c). According to U.K. CAA, if
the stall warning speed is slower than
the 1g stall speed, the airplane will have
little or no maneuvering capability at
the point that the airplane gives the
pilot a warning of an impending stall.
The U.K. CAA stated that in an
operational scenario, if the airplane
slows to a speed slightly above the stall
warning speed, any attempt to
maneuver the airplane or further reduce
speed could lead to an immediate stall.
This situation is of most concern to the
U.K. CAA in the landing phase because,
unlike the cruise or takeoff phases, there
are limited options for the crew to
recover from a stall. The airplane is
already at low altitude and descending
towards the ground, the power setting is
low, and the potential to trade height for
speed is extremely limited.
Due to this concern, the U.K. CAA
recommended making the non-icing
stall warning speed margin
requirements of § 25.207(c) and (d) also
apply to icing conditions, but only
when the airplane is in the landing
configuration. Since the proposed
§ 25.207(e) was intended to be used in
place of § 25.207(c) and (d) for icing
conditions, the U.K. CAA suggested
that, if § 25.207(c) and (d) are applied to
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the landing configuration in icing
conditions, then § 25.207(e) need not be
applied to the landing configuration.
In developing the proposed rule, the
FAA accepted a determination by the
Flight Test Harmonization Working
Group (FTHWG) that the same handling
qualities standards should generally
apply to flight in icing conditions as
apply to flight in non-icing conditions.
In certain areas, however, the FTHWG
decided that the handling qualities
standards for non-icing conditions were
inappropriate for flight in icing
conditions. In these areas, the FTHWG
recommended alternative criteria for
flight in icing conditions.
The stall warning margin was one of
the areas where the FTHWG
recommended alternative criteria for
flight in icing conditions. The FTHWG
determined that applying the existing
stall warning margin requirements of
§ 25.207(c) and (d) to icing conditions
would be far more stringent than the
best current practices and would unduly
penalize designs that have not exhibited
safety problems in icing conditions. The
FTHWG further determined the stall
warning requirements of the existing
§ 25.207(c) and (d) could be made less
stringent for icing conditions without
compromising safety. As a result, we
proposed the less stringent § 25.207(e)
to address stall warning margin
requirements for icing conditions in
place of § 25.207(c) and (d).
No changes have been made to this
final rule as a result of the U.K. CAA’s
comment. We acknowledge that the
U.K. CAA has pointed out a deficiency
with safety implications in the proposed
stall warning requirements. However,
U.S. manufacturers’ initial cost analysis
of the U.K. CAA’s recommended
changes indicates these changes may
significantly increase the costs of this
rulemaking beyond the benefits
provided due to uncertainties in how
the increased stall warning margin
requirement would affect airplane type
certification testing, certification
program schedules, and the design of
stall warning systems.
In addition, the U.K. CAA’s
recommended changes would introduce
significant regulatory differences from
EASA’s airworthiness certification
requirements, and might not completely
resolve the potential safety issue. For
these reasons we believe that additional
time and aviation industry participation
are needed to determine an appropriate
way to address this safety concern.
However, we do not believe it is
appropriate to delay issuance of this
final rule pending resolution of this
issue.
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This final rule significantly improves
the affected airworthiness standards and
the benefits of these improvements
should be achieved as soon as possible.
It also satisfies a number of important
NTSB recommendations. As these
improvements are being implemented,
we will continue to work closely with
EASA and industry to address the issue
raised by the U.K. CAA. This subject has
been included on EASA’s 2008
rulemaking agenda, and we will work
with them in that context to agree on a
harmonized approach. Once these
efforts are completed, we will initiate
new rulemaking, if appropriate, to adopt
any necessary revisions to part 25.
11. Stall and Stall Warning
Requirements Prior to Activation of the
IPS
Proposed § 25.207(h)(2)(ii) would
require compliance with the stall
characteristics requirements of § 25.203,
using the stall demonstration prescribed
by § 25.201, for flight in icing conditions
before the IPS is activated. This
requirement would apply if the stall
warning required by § 25.207 is
provided by a different means for flight
in icing conditions than for non-icing
conditions. The stall demonstration
prescribed by § 25.201 requires that the
stalling maneuver be continued to the
point where the airplane gives the pilot
a clear and distinctive indication of an
acceptable nature that the airplane is
stalled.
Raytheon disagreed with this proposal
because the ice accretion resulting from
a delay in activating the IPS is a short
term transient condition. According to
Raytheon, the intent should be to
demonstrate only the ability to prevent
a stall, rather than to also ensure that
the airplane has good stall
characteristics. Raytheon stated that it is
unnecessary to consider that the pilot
might ignore the stall buffeting and
continue to increase angle-of-attack
until the airplane is stalled. To comply
with the proposed rule, Raytheon
argued that an airplane with a stick
pusher stall identification system would
be required to have its stick pusher
activation based on a contaminated
wing leading edge for non-icing
conditions. This would require
increased takeoff and landing speeds
and negatively impact all takeoff and
landing performance.
Raytheon also stated that the cost
impacts would be excessive for what is
only a transient condition. Raytheon’s
position is that there is no need to
consider the airplane’s handling
qualities after it has stalled. It should be
sufficient to show that the pilot can
prevent stalling if the recovery
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maneuver is not begun until at least
three seconds after the onset of stall
warning, which is also required by the
proposed § 25.207(h)(2)(ii).
We do not agree with Raytheon’s
comments. Because of human factors
considerations, proposed § 25.207(b)
generally requires that the same means
of providing a stall warning be used in
both icing and non-icing conditions.
Therefore, if a stick shaker is used for
stall warning in non-icing conditions (as
is the case for most transport category
airplanes) it must also be used for stall
warning in icing conditions. The reason
for this proposed requirement is that in
icing accidents and incidents where the
airplane stalled before the stick shaker
activated, flightcrews have not
recognized the buffeting associated with
ice contamination in time to prevent
stalling. Proposed § 25.207(h)(2)(ii)
allows a different means of providing
stall warning in icing conditions only
for the relatively short time period
between when the airplane first enters
icing conditions and when the IPS is
activated. (This exception to the
proposed § 25.207(b) is further limited
such that it only applies when the
procedures for activating the IPS do not
involve waiting until a certain amount
of ice has been accumulated.)
Because there is still a safety concern
with flightcrews recognizing a stall
warning that is provided by a different
means than the flightcrew would
normally experience, we consider it
essential that the airplane also be shown
to have safe stall characteristics. Poor
stalling characteristics with an iced
wing have directly contributed to the
severity of icing accidents involving a
stall in icing conditions.
As for Raytheon’s comment about the
cost impacts, we evaluated these as part
of the regulatory evaluation conducted
for the NPRM, and we do not agree that
the cost impacts associated with this
requirement are excessive. In addition,
the adopted § 25.207 will not require
airplanes with stick pusher stall
identification systems to have their stick
pusher activation based on a
contaminated wing leading edge for
non-icing conditions. Section
25.207(h)(2)(ii) does not apply if the
same stall warning means is used for
non-icing and icing conditions. If a stick
shaker is used for stall warning and if
the stick shaker activation point must be
advanced due to the effect of the ice
accreted before activation of the IPS,
this would result in the same negative
effect on takeoff and landing speeds.
However, if the procedures for
activating the IPS ensure that it is
activated before any ice accretes on the
wings, neither the stick shaker
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activation point nor the takeoff and
landing speeds will be affected. This
could be accomplished, for example, by
using an ice detector that would activate
the IPS before ice accretes on the wings,
or by procedures for activating the IPS
based on environmental conditions
conducive to icing, but before ice would
actually accrete on the wings.
12. Dissipation of Ice Shapes at High
Altitudes and High Mach Numbers
Proposed § 25.253(c) specifies the
maximum speed for demonstrating
stability characteristics in icing
conditions. Proposed § 25.253(c)(3)
allows this speed to be limited to the
speed at which it is demonstrated that
the airframe will be free of ice accretion
due to the effects of increased dynamic
pressure. Raytheon stated that
experience has shown that ice shapes
dissipate quickly at high altitude and
high Mach numbers. Raytheon
suggested revising § 25.253(c)(3) to
specify the altitude and/or Mach
number range that ice shapes would
dissipate.
Although we agree that past
experience shows that ice shapes
dissipate or detach at high altitude and
high Mach numbers, the applicable
range may vary with airplane type. The
particular conditions under which the
ice accretions dissipate or detach should
be justified as part of the certification
program. Since this is consistent with
proposed § 25.253(c), we made no
changes to the final rule.
13. Critical Ice Shapes
Proposed appendix C, part II(a)
defines how to determine the critical ice
accretions for each phase of flight. The
NTSB commented that for each phase of
flight, the applicant should be required
to demonstrate that the shape,
chordwise and spanwise, and the
roughness of the shapes accurately
reflect the full range of appendix C
conditions in terms of mean effective
drop diameter, liquid water content, and
temperature during each phase of flight.
Additionally, the NTSB suggested that
we review the justification and selection
of the most critical ice shape for each
phase of flight.
Although we believe the proposed
requirements already address the
NTSB’s concerns, we have revised
appendix C, part II(a) for additional
clarity. We added text to state that
applicants must demonstrate that the
full range of atmospheric icing
conditions specified in part I of
appendix C have been considered,
including the mean effective drop
diameter, liquid water content, and
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temperature appropriate to the flight
conditions.
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14. Takeoff Ice Accretions
ALPA noted that the takeoff ice
accretions defined in proposed
appendix C, part II(a)(2) do not include
the entire takeoff flight path. As defined
in § 25.111, the takeoff flight path ends
at either 1,500 feet above the takeoff
surface, or the height at which the
transition from the takeoff to the en
route configuration is completed and
the final takeoff speed (VFTO) is reached,
whichever is higher. The takeoff flight
path in proposed appendix C, part
II(a)(2) ends at 1,500 feet above the
takeoff surface. ALPA stated that there
are many mountainous airport locations
where the takeoff configuration must be
maintained above 1,500 feet above the
takeoff surface for terrain clearance at
maximum takeoff gross weights. Since
winter operations in these locations
often involve icing conditions, ALPA
requested that the takeoff flight path of
Appendix C, part II(a)(2) be revised to
match that of § 25.111.
ALPA’s comment points out an
oversight in the text of the proposal.
Appendix C, part II(a)(2) has been
revised to include the entire takeoff
flight path as defined in § 25.111. We
consider this to be a technical
clarification that does not impose a
significant additional burden on
applicants.
15. Size of Ice Accretion Before
Activation of the IPS
For the pre-activation ice identified in
Appendix C, part II(e), ALPA did not
support the 30-second time period for
the flightcrew to see and respond to ice
accreting on the airplane as stated in
paragraphs 2c(4)(a) and (b) of Appendix
1, Airframe Ice Accretion, of proposed
AC 25.21–1X. ALPA believes that the
ice accreted during a more operationally
realistic timeframe and the potential
degradations in aircraft performance
and handling qualities must be
accounted for during certification in
order to make the proposed
requirements and acceptable means of
compliance an effective combination.
While a well designed human factors
study could determine an appropriate
time, ALPA proposed that at least the 2minute time period contained in 14 CFR
33.77, Foreign object ingestion—ice, be
used as the time to visually recognize
ice is accreting until definitive studies
can be completed.
The FAA believes that ALPA has
misunderstood the use of the 30-second
time period in the proposed AC 25.21–
1X acceptable means of compliance.
The FAA does not expect the flightcrew
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to see and respond to ice accumulating
on the airplane within 30 seconds. In
accordance with § 25.21(g), compliance
must be shown using ice accretions
consistent with the AFM operating
procedures. First, applicants must
determine the ice accretion that would
be on the airplane when the AFM
procedures call for activating the IPS.
Then, the 30-second time period is used
in combination with the continuous
maximum icing environment, as defined
in appendix C of part 25, as a standard
for determining the additional ice that
could accrete on the airplane before the
pilot actually activates the IPS. Since
the appendix C maximum continuous
icing envelope represents at least the
99th percentile of encounters with
continuous maximum icing (that is,
99% of the time, less icing would
occur), it would take significantly longer
than 30 seconds in nearly all actual
icing events for the airplane to accrete
this much ice.
As a result of this comment, the FAA
reviewed the proposed AC 25.21–1X
text. Although the use of a-30 second
time period in a continuous maximum
icing environment is clearly stated, the
FAA believes that the text is incomplete
regarding what we expect applicants to
consider in determining the ice
accretion specified by the AFM
procedures for activating the IPS. The
FAA is revising the proposed AC to
state that this ice accretion should be
easily recognizable by the pilot under
all foreseeable conditions (for example,
at night in clouds). No changes have
been made to the regulatory
requirements.
16. Maximum Size of the Critical Ice
Accretion
Dassault noted that, in Europe, the
critical ice accretion is limited to a
maximum thickness of 3 inches.
Dassault did not find such a limitation
in the NPRM, nor in the proposed
advisory circular (AC) 25.21–1X related
to the NPRM. Dassault noted that this
omission could result in carrying out
performance and handling tests with
unrealistic ice accretions (particularly
those assumed to build up on the
unprotected parts of the airplane during
the 45-minute holding flight phase
referenced in ACs 25.21–X and
25.1419–1A).
We did not make any changes to the
final rule because several existing ACs
provide guidance for the size of the
most critical ice accretions that should
be considered. This longstanding
guidance considers a 45-minute holding
condition within an icing cloud. Since
this guidance is not regulatory, we have
accepted applicants’ use of service
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history and other experience with other
compliance criteria to determine the
maximum ice accretion that needs to be
considered. We will continue to address
this issue in the same manner. The AC
being issued along with this final rule
refers to these alternative methods of
compliance and provides guidance for
their use.
17. Detection of Icing Conditions
A private citizen commented that
icing conditions should be monitored by
more than the pilot’s eyesight. We are
unable to address the commenter’s issue
in this rulemaking because this
rulemaking only addresses performance
and handling qualities requirements for
the current methods of ice detection
(which include detection by visual
means). However, we are pursuing
separate rulemaking for future airplane
designs relative to allowable methods
for detecting icing and determining
when to activate the IPS. In NPRM 07–
07, ‘‘Activation of Ice Protection,’’
published in the Federal Register on
April 26, 2007, we proposed to amend
the airworthiness standards applicable
to transport category airplanes to require
a means to ensure timely activation of
the airframe IPS.
18. Delayed Activation of the IPS
ALPA recommended modifying all
rule language to eliminate references
and rule provisions for waiting until a
finite amount of ice has accumulated
before activating the IPS. ALPA stated
that delayed activation of the IPS has
been a factor in several accidents and
incidents. ALPA also pointed out that
the FAA has adopted 17 airworthiness
directives requiring immediate
activation of IPS at the first sign of ice
accretion for a number of airplane types
where the previous practice was to wait
until a specified amount of ice had
accumulated on the airplane. ALPA
noted that after an exhaustive review of
accident and incident data, ARAC
recommended an operating rule that
would remove the option of delaying
activation of the IPS.
Except for the airworthiness
directives referenced by ALPA, current
regulations do not prohibit AFM
procedures that call for delaying
activation of the IPS until a specified
amount of ice has accreted. Although
we strongly encourage activating the IPS
at the first sign of ice accretion, there
may be some designs for which delayed
activation is currently acceptable, safe,
and appropriate. For example, some
thermal wing IPS can currently be used
in either an anti-ice or deice mode. In
the deice mode, the wing IPS is not
activated until a certain amount of ice
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has accreted. This has not resulted in
any safety issues, and can be a more
economical way of operating the wing
IPS.
The purpose of this rulemaking is to
provide appropriate performance and
handling qualities requirements,
considering the currently accepted
procedures for activating the IPS.
Establishing new requirements for
acceptable methods for activating the
IPS is beyond the scope of this
rulemaking. As ALPA noted, however,
ARAC has recommended the FAA adopt
new requirements that would ensure
flightcrews are provided with a clear
means to know when to activate the IPS
in a timely manner. We are pursuing
separate rulemaking in response to this
ARAC recommendation. In NPRM 07–
07, ‘‘Activation of Ice Protection,’’
published in the Federal Register on
April 26, 2007, we proposed to amend
the airworthiness standards applicable
to transport category airplanes to require
a means to ensure timely activation of
the airframe IPS. We will update the
requirements adopted by this final rule
related to the means of activating the
IPS, if necessary, to be consistent with
any final action resulting from NPRM
07–07, ‘‘Activation of Ice Protection.’’
19. Harmonization With EASA’s NPA
Several commenters noted that the
FAA did not fully harmonize the NPRM
with the EASA’s NPA covering the same
icing-related safety issues. They
recommended harmonizing the two rule
proposals.
We worked closely with EASA to
ensure that there are no significant
regulatory differences between this
amendment and EASA’s anticipated
final rule. However, since EASA’s final
rule has not yet been issued, we cannot
guarantee that the two final rules will be
completely harmonized. We believe that
any differences will be primarily
editorial and not significant regulatory
differences.
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20. Accuracy of the Regulatory
Flexibility Evaluation
GAMA requested that the FAA review
the regulatory flexibility evaluation in
the interest of accuracy.
We reviewed the regulatory flexibility
evaluation and reaffirmed the
determination that this proposed rule
would not have a significant economic
impact on a substantial number of small
entities. All U.S. part 25 aircraft
manufacturers exceed the Small
Business Administration small-entity
criteria of 1,500 employees for aircraft
manufacturers.
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21. Aircraft Population Used When
Determining Cost Versus Benefit
GAMA stated that it appeared the cost
proposal considered U.S. manufactured
aircraft while the benefit section
included international products. GAMA
believes that the same aircraft
population should be used when
determining cost versus benefit.
Additionally, GAMA stated that it
appeared it was assumed that cost was
only attributed to entirely new TC
products. GAMA believes it would be
appropriate to consider the economic
impact to some amount of amended TC
and STC projects as well.
Section 1 of Executive Order 12866
states ‘‘Federal agencies should
promulgate only such regulations as are
required by law, are necessary to
interpret the law, or are made necessary
by compelling public need, such as
material failures of private markets to
protect or improve the health and safety
of the public, the environment, or the
well-being of the American people.’’
Section 5 states ‘‘In order to reduce the
regulatory burden on the American
people, their families, their
communities, their State, local, and
tribal governments and their industries
* * *.’’ Therefore, regulatory
evaluations and flexibility analyses
focus on American people and
American industries.
American industries, such as
manufacturers and operators of aircraft,
must comply with regulations
promulgated by Federal agencies.
Foreign firms are not required to comply
with U.S. regulations unless they choose
to sell or operate their aircraft in
America.
We determined the costs for this
proposal by analyzing only American
manufacturing industries, since foreign
firms are not required to comply with
U.S. regulations unless they choose to
sell or operate their aircraft in America.
While we do consider foreign
manufactured aircraft in the benefit
section, we determined the benefits by
analyzing only American operators of
those aircraft. Hence, the intent of
Executive Order 12866 was satisfied.
We did include amended TCs in the
analysis. Each TC includes all
derivatives for a particular aircraft
model. For example, TC No. A16WE
initially covered only the Boeing 737–
100, but was later amended to include
the –200 through –900 Boeing 737
models.
Future applicants for approval of
changed products are subject to § 21.101
(Changed Product Rule). There are
several provisions of § 21.101 allowing
future applicants of changed products to
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comply with earlier regulation
amendments. We have already
determined that benefits of the Changed
Product Rule exceed the costs.
Therefore, we do not estimate the
benefits and costs of changed products
for new certification rules.
22. Value of Fatalities Avoided
A private citizen claimed that the
value of the fatalities avoided by this
proposal would be in the neighborhood
of $20 billion.
The number of averted fatalities and
injuries is based on the historical
accident rate extrapolated into the
future. The FAA used $3.0 million for
an avoided fatality and $132,700 for the
additional associated medical and legal
costs’ for a fatality. The derivation for
these values is discussed in the
‘‘Economic Values for FAA Investment
and Regulatory Decisions, A Guide.’’ 6
Without the rule, we expect that over
the 45-year analysis period,
approximately three accidents will
occur. These three accidents are
expected to result in approximately 12
fatalities, six serious injuries, and two
minor injuries. From these values, and
expected future accidents based on past
accident history, we estimated a benefit
of about $90 million over the 45-year
analysis period.
III. Rulemaking Analyses and Notices
Paperwork Reduction Act
There are no current or new
requirements for information collection
associated with this amendment.
International Compatibility
In keeping with U.S. obligations
under the Convention on International
Civil Aviation, it is FAA policy to
comply with International Civil
Aviation Organization (ICAO) Standards
and Recommended Practices to the
maximum extent practicable. The FAA
has determined that there are no ICAO
Standards and Recommended Practices
that correspond to these regulations.
Economic Assessment, Regulatory
Flexibility Determination, Trade Impact
Assessment, and Unfunded Mandates
Assessment
Changes to Federal regulations must
undergo several economic analyses.
First, Executive Order 12866 directs
each Federal agency to propose or adopt
a regulation only upon a reasoned
determination that the benefits of the
intended regulation justify its costs.
6 https://www.faa.gov/regulations_policies/
policy_guidance/benefit_cost/media/050404%20
Critical%20Values%20Dec%2031%20Report
%2007Jan05.pdf.
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$52.5 million in additional fuel-burn.
We estimate the total cost of this final
rule to be about $62.3 million and the
seven percent present value cost of the
rule will be about $23.0 million.
Introduction
This portion of the preamble
summarizes the FAA’s analysis of the
economic impacts of a final rule
amending part 25 of Title 14, Code of
Federal Regulations (14 CFR) to change
the regulations applicable to transport
category airplanes certificated for flight
in icing conditions. It also includes
summaries of the regulatory flexibility
determination, the international trade
impact assessment, and the unfunded
mandates assessment. We suggest
readers seeking greater detail read the
full regulatory evaluation, a copy of
which we have placed in the docket for
this rulemaking.
mstockstill on PROD1PC66 with RULES2
Second, the Regulatory Flexibility Act
of 1980 requires agencies to analyze the
economic impact of regulatory changes
on small entities. Third, the Trade
Agreements Act (19 U.S.C. 2531–2533)
prohibits agencies from setting
standards that create unnecessary
obstacles to the foreign commerce of the
United States. In developing U.S.
standards, this Trade Act also requires
agencies to consider international
standards and, where appropriate, use
them as the basis of U.S. standards.
Fourth, the Unfunded Mandates Reform
Act of 1995 (Pub. L. 104–4) requires
agencies to prepare a written assessment
of the costs, benefits, and other effects
of proposed or final rules that include
a Federal mandate likely to result in the
expenditure by State, local, or tribal
governments, in the aggregate, or by the
private sector, of $100 million or more
annually (adjusted for inflation with the
base year of 1995.)
In conducting these analyses, FAA
has determined this rule (1) has benefits
that justify its costs, is not a ‘‘significant
regulatory action’’ as defined in section
3(f) of Executive Order 12866 and is not
‘‘significant’’ as defined in DOT’s
Regulatory Policies and Procedures; (2)
will not have a significant economic
impact on a substantial number of small
entities; (3) will not reduce barriers to
international trade; and (4) does not
impose an unfunded mandate on state,
local, or tribal governments, or on the
private sector. These analyses, available
in the docket, are summarized below.
The benefits of this final rule consist
of the value of lives saved due to
avoiding three accidents involving part
25 airplanes operating in icing
conditions. Based on the historic
accident rate, we estimate that a total of
12 fatalities could potentially be
avoided by adopting the final rule. Over
the 45-year period of analysis, the
potential benefit of the propose rule will
be $89.2 million ($23.6 million in
present value at seven percent).
Total Benefits and Costs of This
Rulemaking
The estimated potential benefits of
avoiding 3 accidents over the 45-year
analysis interval are $89.2 million
($23.6 million in present value at seven
percent). To obtain these benefits, over
the 45-year analysis interval,
manufacturers will incur additional
certification costs of $9.8 million and
the operators of these airplanes will pay
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Who Is Potentially Affected by This
Rulemaking
• Operators of part 25 U.S.-registered
aircraft conducting operations under
FAR Parts 121, 129, and 135, and
• Manufacturers of those part 25
aircraft.
Our Cost Assumptions and Sources of
Information
This evaluation makes the following
assumptions:
1. This final rule is assumed to
become effective immediately.
2. The production runs for newly
certificated part 25 airplane models is
20 years.
3. The average life of a part 25
airplane is 25 years.
4. We analyzed the costs and benefits
of this final rule over the 45-year period
(20 + 25 = 45) 2006 through 2050.
5. We used a 10-year certification
compliance period. For the 10-year lifecycle period, the FAA calculated an
average of four new certifications will
occur.
6. We used $3.0 million as the value
of an avoided fatality.
7. New airplane certifications will
occur in year one of the analysis time
period.
Benefits of This Rulemaking
Costs of This Rulemaking
We estimate the costs of this final rule
to be about $62.3 million ($23.0 million
in present value at seven percent) over
the 45-year analysis period. The total
cost of $62.3 million equals the fixed
certification costs of $9.8 million
incurred in the first year plus the
variable annual fuel burn cost of $52.5
million over the 45-year analysis period.
Regulatory Flexibility Determination
The Regulatory Flexibility Act of 1980
(Pub. L. 96–354) (RFA) establishes ‘‘as a
principle of regulatory issuance that
agencies shall endeavor, consistent with
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the objectives of the rule and of
applicable statutes, to fit regulatory and
informational requirements to the scale
of the businesses, organizations, and
governmental jurisdictions subject to
regulation. To achieve this principle,
agencies are required to solicit and
consider flexible regulatory proposals
and to explain the rationale for their
actions to assure that such proposals are
given serious consideration.’’ The RFA
covers a wide-range of small entities,
including small businesses, not-forprofit organizations, and small
governmental jurisdictions.
Agencies must perform a review to
determine whether a rule will have a
significant economic impact on a
substantial number of small entities. If
the agency determines that it will, the
agency must prepare a regulatory
flexibility analysis as described in the
RFA.
However, if an agency determines that
a rule is not expected to have a
significant economic impact on a
substantial number of small entities,
section 605(b) of the RFA provides that
the head of the agency may so certify
and a regulatory flexibility analysis is
not required. The certification must
include a statement providing the
factual basis for this determination, and
the reasoning should be clear.
In the interest of accuracy, one
commenter requested we review the
determination we made in the proposed
rules regulatory flexibility evaluation.
We reviewed the determination from the
proposed rule and came to the same
conclusions for this final rule for the
reasons discussed below.
Currently U.S. manufactured part 25
aircraft type certificate holders include:
The Boeing Company, Cessna Aircraft
Company (a subsidiary of Textron Inc.),
Raytheon Company, and Gulfstream
Aerospace Corporation (a wholly owned
subsidiary of General Dynamics). All
United States part 25 aircraft
manufacturers exceed the Small
Business Administration small-entity
criteria of 1,500 employees for aircraft
manufacturers.
This rule will add an additional
weighted average monthly fuel burn
cost of about $42 per airplane, which is
less than an hour of fuel burn and thus
a minimal additional cost to all
operators.
Given that manufacturers are not
small entities and operators incur a
minimal additional cost, as the FAA
Administrator, I certify that this final
rule will not have a significant
economic impact on a substantial
number of small entities.
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International Trade Impact Assessment
The Trade Agreements Act of 1979
(Pub. L. 96–39) prohibits Federal
agencies from establishing any
standards or engaging in related
activities that create unnecessary
obstacles to the foreign commerce of the
United States. Legitimate domestic
objectives, such as safety, are not
considered unnecessary obstacles. The
statute also requires consideration of
international standards and, where
appropriate, that they be the basis for
U.S. standards. The FAA has assessed
the potential effect of this final rule and
determined that it will impose the same
costs on domestic and international
entities and thus has a neutral trade
impact.
based on the administrative record of
this rulemaking, that there is no need to
make any regulatory distinctions
applicable to intrastate aviation in
Alaska.
Unfunded Mandates Assessment
Title II of the Unfunded Mandates
Reform Act of 1995 (Pub. L. 104–4)
requires each Federal agency to prepare
a written statement assessing the effects
of any Federal mandate in a proposed or
final agency rule that may result in an
expenditure of $100 million or more
(adjusted annually for inflation with the
base year 1995) in any one year by State,
local, and tribal governments, in the
aggregate, or by the private sector; such
a mandate is deemed to be a ‘‘significant
regulatory action.’’ The FAA currently
uses an inflation-adjusted value of
$128.1 million in lieu of $100 million.
This final rule does not contain such
a mandate. The requirements of Title II
do not apply.
Regulations That Significantly Affect
Energy Supply, Distribution, or Use
The FAA has analyzed this final rule
under Executive Order 13211, Actions
Concerning Regulations that
Significantly Affect Energy Supply,
Distribution, or Use (May 18, 2001). We
have determined that it is not a
‘‘significant energy action,’’ and it is not
likely to have a significant adverse effect
on the supply, distribution, or use of
energy.
mstockstill on PROD1PC66 with RULES2
Executive Order 13132, Federalism
The FAA has analyzed this final rule
under the principles and criteria of
Executive Order 13132, Federalism. We
determined that this action will not
have a substantial direct effect on the
States, or the relationship between the
national Government and the States, or
on the distribution of power and
responsibilities among the various
levels of government, and therefore does
not have federalism implications.
Regulations Affecting Intrastate
Aviation in Alaska
Section 1205 of the FAA
Reauthorization Act of 1996 (110 Stat.
3213) requires the FAA, when
modifying its regulations in a manner
affecting intrastate aviation in Alaska, to
consider the extent to which Alaska is
not served by transportation modes
other than aviation, and to establish
appropriate regulatory distinctions. In
the NPRM, we requested comments on
whether the proposed rule should apply
differently to intrastate operations in
Alaska. We didn’t receive any
comments, and we have determined,
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Environmental Analysis
FAA Order 1050.1E identifies FAA
actions that are categorically excluded
from preparation of an environmental
assessment or environmental impact
statement under the National
Environmental Policy Act in the
absence of extraordinary circumstances.
The FAA has determined this
rulemaking action qualifies for the
categorical exclusion identified in
paragraph 312f and involves no
extraordinary circumstances.
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting
and recordkeeping requirements.
The Amendment
In consideration of the foregoing, the
Federal Aviation Administration
amends part 25 of Title 14, Code of
Federal Regulations, as follows:
I
PART 25—AIRWORTHINESS
STANDARDS: TRANSPORT
CATEGORY AIRPLANES
1. The authority citation for part 25
continues to read as follows:
I
Authority: 49 U.S.C. 106(g), 40113, 44701,
44702, and 44704.
2. Amend § 25.21 by adding a new
paragraph (g) to read as follows:
I
§ 25.21
Proof of compliance.
*
*
*
*
*
(g) The requirements of this subpart
associated with icing conditions apply
only if the applicant is seeking
certification for flight in icing
conditions.
(1) Each requirement of this subpart,
except §§ 25.121(a), 25.123(c),
25.143(b)(1) and (b)(2), 25.149,
25.201(c)(2), 25.207(c) and (d), 25.239,
and 25.251(b) through (e), must be met
in icing conditions. Compliance must be
shown using the ice accretions defined
in appendix C, assuming normal
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44665
operation of the airplane and its ice
protection system in accordance with
the operating limitations and operating
procedures established by the applicant
and provided in the Airplane Flight
Manual.
(2) No changes in the load
distribution limits of § 25.23, the weight
limits of § 25.25 (except where limited
by performance requirements of this
subpart), and the center of gravity limits
of § 25.27, from those for non-icing
conditions, are allowed for flight in
icing conditions or with ice accretion.
3. Amend § 25.103 by revising
paragraph (b)(3) to read as follows:
I
§ 25.103
Stall speed.
*
*
*
*
*
(b) * * *
(3) The airplane in other respects
(such as flaps, landing gear, and ice
accretions) in the condition existing in
the test or performance standard in
which VSR is being used;
*
*
*
*
*
4. Amend § 25.105 by revising
paragraph (a) to read as follows:
I
§ 25.105
Takeoff.
(a) The takeoff speeds prescribed by
§ 25.107, the accelerate-stop distance
prescribed by § 25.109, the takeoff path
prescribed by § 25.111, the takeoff
distance and takeoff run prescribed by
§ 25.113, and the net takeoff flight path
prescribed by § 25.115, must be
determined in the selected configuration
for takeoff at each weight, altitude, and
ambient temperature within the
operational limits selected by the
applicant—
(1) In non-icing conditions; and
(2) In icing conditions, if in the
configuration of § 25.121(b) with the
takeoff ice accretion defined in
appendix C:
(i) The stall speed at maximum takeoff
weight exceeds that in non-icing
conditions by more than the greater of
3 knots CAS or 3 percent of VSR; or
(ii) The degradation of the gradient of
climb determined in accordance with
§ 25.121(b) is greater than one-half of
the applicable actual-to-net takeoff flight
path gradient reduction defined in
§ 25.115(b).
*
*
*
*
*
5. Amend § 25.107 by revising
paragraph (c)(3) and (g)(2) and adding
new paragraph (h) to read as follows:
I
§ 25.107
*
Takeoff speeds.
*
*
(c) * * *
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*
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(3) A speed that provides the
maneuvering capability specified in
§ 25.143(h).
*
*
*
*
*
(g) * * *
(2) A speed that provides the
maneuvering capability specified in
§ 25.143(h).
(h) In determining the takeoff speeds
V1, VR, and V2 for flight in icing
conditions, the values of VMCG, VMC,
and VMU determined for non-icing
conditions may be used.
I 6. Amend § 25.111 by revising
paragraph (c)(3)(iii), (c)(4), and adding a
new paragraph (c)(5) to read as follows:
§ 25.111
Takeoff path.
*
*
*
*
*
(c) * * *
(3) * * *
(iii) 1.7 percent for four-engine
airplanes.
(4) The airplane configuration may
not be changed, except for gear
retraction and automatic propeller
feathering, and no change in power or
thrust that requires action by the pilot
may be made until the airplane is 400
feet above the takeoff surface; and
(5) If § 25.105(a)(2) requires the
takeoff path to be determined for flight
in icing conditions, the airborne part of
the takeoff must be based on the
airplane drag:
(i) With the takeoff ice accretion
defined in appendix C, from a height of
35 feet above the takeoff surface up to
the point where the airplane is 400 feet
above the takeoff surface; and
(ii) With the final takeoff ice accretion
defined in appendix C, from the point
where the airplane is 400 feet above the
takeoff surface to the end of the takeoff
path.
*
*
*
*
*
I 7. Revise § 25.119 to read as follows:
mstockstill on PROD1PC66 with RULES2
§ 25.119 Landing climb: All-enginesoperating.
In the landing configuration, the
steady gradient of climb may not be less
than 3.2 percent, with the engines at the
power or thrust that is available 8
seconds after initiation of movement of
the power or thrust controls from the
minimum flight idle to the go-around
power or thrust setting—
(a) In non-icing conditions, with a
climb speed of VREF determined in
accordance with § 25.125(b)(2)(i); and
(b) In icing conditions with the
landing ice accretion defined in
appendix C, and with a climb speed of
VREF determined in accordance with
§ 25.125(b)(2)(ii).
I 8. Amend § 25.121 by revising
paragraphs (b), (c), and (d) to read as
follows:
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§ 25.121
Climb: One-engine inoperative.
*
*
*
*
*
(b) Takeoff; landing gear retracted. In
the takeoff configuration existing at the
point of the flight path at which the
landing gear is fully retracted, and in
the configuration used in § 25.111 but
without ground effect:
(1) The steady gradient of climb may
not be less than 2.4 percent for twoengine airplanes, 2.7 percent for threeengine airplanes, and 3.0 percent for
four-engine airplanes, at V2 with:
(i) The critical engine inoperative, the
remaining engines at the takeoff power
or thrust available at the time the
landing gear is fully retracted,
determined under § 25.111, unless there
is a more critical power operating
condition existing later along the flight
path but before the point where the
airplane reaches a height of 400 feet
above the takeoff surface; and
(ii) The weight equal to the weight
existing when the airplane’s landing
gear is fully retracted, determined under
§ 25.111.
(2) The requirements of paragraph
(b)(1) of this section must be met:
(i) In non-icing conditions; and
(ii) In icing conditions with the
takeoff ice accretion defined in
appendix C, if in the configuration of
§ 25.121(b) with the takeoff ice
accretion:
(A) The stall speed at maximum
takeoff weight exceeds that in non-icing
conditions by more than the greater of
3 knots CAS or 3 percent of VSR; or
(B) The degradation of the gradient of
climb determined in accordance with
§ 25.121(b) is greater than one-half of
the applicable actual-to-net takeoff flight
path gradient reduction defined in
§ 25.115(b).
(c) Final takeoff. In the en route
configuration at the end of the takeoff
path determined in accordance with
§ 25.111:
(1) The steady gradient of climb may
not be less than 1.2 percent for twoengine airplanes, 1.5 percent for threeengine airplanes, and 1.7 percent for
four-engine airplanes, at VFTO with—
(i) The critical engine inoperative and
the remaining engines at the available
maximum continuous power or thrust;
and
(ii) The weight equal to the weight
existing at the end of the takeoff path,
determined under § 25.111.
(2) The requirements of paragraph
(c)(1) of this section must be met:
(i) In non-icing conditions; and
(ii) In icing conditions with the final
takeoff ice accretion defined in
appendix C, if in the configuration of
§ 25.121(b) with the takeoff ice
accretion:
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(A) The stall speed at maximum
takeoff weight exceeds that in non-icing
conditions by more than the greater of
3 knots CAS or 3 percent of VSR; or
(B) The degradation of the gradient of
climb determined in accordance with
§ 25.121(b) is greater than one-half of
the applicable actual-to-net takeoff flight
path gradient reduction defined in
§ 25.115(b).
(d) Approach. In a configuration
corresponding to the normal all-enginesoperating procedure in which VSR for
this configuration does not exceed 110
percent of the VSR for the related allengines-operating landing configuration:
(1) The steady gradient of climb may
not be less than 2.1 percent for twoengine airplanes, 2.4 percent for threeengine airplanes, and 2.7 percent for
four-engine airplanes, with—
(i) The critical engine inoperative, the
remaining engines at the go-around
power or thrust setting;
(ii) The maximum landing weight;
(iii) A climb speed established in
connection with normal landing
procedures, but not exceeding 1.4 VSR;
and
(iv) Landing gear retracted.
(2) The requirements of paragraph
(d)(1) of this section must be met:
(i) In non-icing conditions; and
(ii) In icing conditions with the
approach ice accretion defined in
appendix C. The climb speed selected
for non-icing conditions may be used if
the climb speed for icing conditions,
computed in accordance with paragraph
(d)(1)(iii) of this section, does not
exceed that for non-icing conditions by
more than the greater of 3 knots CAS or
3 percent.
I 9. Amend § 25.123 by revising
paragraph (a) introductory text and
paragraph (b) to read as follows:
§ 25.123
En route flight paths.
(a) For the en route configuration, the
flight paths prescribed in paragraph (b)
and (c) of this section must be
determined at each weight, altitude, and
ambient temperature, within the
operating limits established for the
airplane. The variation of weight along
the flight path, accounting for the
progressive consumption of fuel and oil
by the operating engines, may be
included in the computation. The flight
paths must be determined at a speed not
less than VFTO, with—
* * *
(b) The one-engine-inoperative net
flight path data must represent the
actual climb performance diminished by
a gradient of climb of 1.1 percent for
two-engine airplanes, 1.4 percent for
three-engine airplanes, and 1.6 percent
for four-engine airplanes—
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(1) In non-icing conditions; and
(2) In icing conditions with the en
route ice accretion defined in appendix
C, if:
(i) A speed of 1.18 VSR with the en
route ice accretion exceeds the en route
speed selected for non-icing conditions
by more than the greater of 3 knots CAS
or 3 percent of VSR; or
(ii) The degradation of the gradient of
climb is greater than one-half of the
applicable actual-to-net flight path
reduction defined in paragraph (b) of
this section.
*
*
*
*
*
I 10. Revise § 25.125 to read as follows:
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§ 25.125
Landing.
(a) The horizontal distance necessary
to land and to come to a complete stop
(or to a speed of approximately 3 knots
for water landings) from a point 50 feet
above the landing surface must be
determined (for standard temperatures,
at each weight, altitude, and wind
within the operational limits established
by the applicant for the airplane):
(1) In non-icing conditions; and
(2) In icing conditions with the
landing ice accretion defined in
appendix C if VREF for icing conditions
exceeds VREF for non-icing conditions
by more than 5 knots CAS at the
maximum landing weight.
(b) In determining the distance in
paragraph (a) of this section:
(1) The airplane must be in the
landing configuration.
(2) A stabilized approach, with a
calibrated airspeed of not less than
VREF, must be maintained down to the
50-foot height.
(i) In non-icing conditions, VREF may
not be less than:
(A) 1.23 VSR0;
(B) VMCL established under
§ 25.149(f); and
(C) A speed that provides the
maneuvering capability specified in
§ 25.143(h).
(ii) In icing conditions, VREF may not
be less than:
(A) The speed determined in
paragraph (b)(2)(i) of this section;
(B) 1.23 VSR0 with the landing ice
accretion defined in appendix C if that
speed exceeds VREF for non-icing
conditions by more than 5 knots CAS;
and
(C) A speed that provides the
maneuvering capability specified in
§ 25.143(h) with the landing ice
accretion defined in appendix C.
(3) Changes in configuration, power or
thrust, and speed, must be made in
accordance with the established
procedures for service operation.
(4) The landing must be made without
excessive vertical acceleration, tendency
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to bounce, nose over, ground loop,
porpoise, or water loop.
(5) The landings may not require
exceptional piloting skill or alertness.
(c) For landplanes and amphibians,
the landing distance on land must be
determined on a level, smooth, dry,
hard-surfaced runway. In addition—
(1) The pressures on the wheel
braking systems may not exceed those
specified by the brake manufacturer;
(2) The brakes may not be used so as
to cause excessive wear of brakes or
tires; and
(3) Means other than wheel brakes
may be used if that means—
(i) Is safe and reliable;
(ii) Is used so that consistent results
can be expected in service; and
(iii) Is such that exceptional skill is
not required to control the airplane.
(d) For seaplanes and amphibians, the
landing distance on water must be
determined on smooth water.
(e) For skiplanes, the landing distance
on snow must be determined on
smooth, dry, snow.
(f) The landing distance data must
include correction factors for not more
than 50 percent of the nominal wind
components along the landing path
opposite to the direction of landing, and
not less than 150 percent of the nominal
wind components along the landing
path in the direction of landing.
(g) If any device is used that depends
on the operation of any engine, and if
the landing distance would be
noticeably increased when a landing is
made with that engine inoperative, the
landing distance must be determined
with that engine inoperative unless the
use of compensating means will result
in a landing distance not more than that
with each engine operating.
I 11. Amend § 25.143 by redesignating
paragraphs (c) through (g) as paragraphs
(d) through (h) respectively; adding a
new paragraph (c); revising redesignated
paragraphs (d), (e), and (f); amending
redesignated paragraph (h) by removing
the words ‘‘Thrust power setting’’ in the
fourth column of the table and replacing
them with the words ‘‘Thrust/power
setting’’; and adding paragraphs (i), and
(j) to read as follows:
§ 25.143
General.
*
*
*
*
*
(c) The airplane must be shown to be
safely controllable and maneuverable
with the critical ice accretion
appropriate to the phase of flight
defined in appendix C, and with the
critical engine inoperative and its
propeller (if applicable) in the minimum
drag position:
(1) At the minimum V2 for takeoff;
(2) During an approach and goaround; and
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(3) During an approach and landing.
(d) The following table prescribes, for
conventional wheel type controls, the
maximum control forces permitted
during the testing required by paragraph
(a) through (c) of this section:
Force, in
pounds, applied
to the control
wheel or rudder
pedals
For short term
application for
pitch and roll
control—two
hands available for control .................
For short term
application for
pitch and roll
control—one
hand available
for control ......
For short term
application for
yaw control ....
For long term
application .....
Pitch
Roll
Yaw
75
50
50
25
150
10
5
20
(e) Approved operating procedures or
conventional operating practices must
be followed when demonstrating
compliance with the control force
limitations for short term application
that are prescribed in paragraph (d) of
this section. The airplane must be in
trim, or as near to being in trim as
practical, in the preceding steady flight
condition. For the takeoff condition, the
airplane must be trimmed according to
the approved operating procedures.
(f) When demonstrating compliance
with the control force limitations for
long term application that are
prescribed in paragraph (d) of this
section, the airplane must be in trim, or
as near to being in trim as practical.
*
*
*
*
*
(i) When demonstrating compliance
with § 25.143 in icing conditions—
(1) Controllability must be
demonstrated with the ice accretion
defined in appendix C that is most
critical for the particular flight phase;
(2) It must be shown that a push force
is required throughout a pushover
maneuver down to a zero g load factor,
or the lowest load factor obtainable if
limited by elevator power or other
design characteristic of the flight control
system. It must be possible to promptly
recover from the maneuver without
exceeding a pull control force of 50
pounds; and
(3) Any changes in force that the pilot
must apply to the pitch control to
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maintain speed with increasing sideslip
angle must be steadily increasing with
no force reversals, unless the change in
control force is gradual and easily
controllable by the pilot without using
exceptional piloting skill, alertness, or
strength.
(j) For flight in icing conditions before
the ice protection system has been
activated and is performing its intended
function, the following requirements
apply:
(1) If activating the ice protection
system depends on the pilot seeing a
specified ice accretion on a reference
surface (not just the first indication of
icing), the requirements of § 25.143
apply with the ice accretion defined in
appendix C, part II(e).
(2) For other means of activating the
ice protection system, it must be
demonstrated in flight with the ice
accretion defined in appendix C, part
II(e) that:
(i) The airplane is controllable in a
pull-up maneuver up to 1.5 g load
factor; and
(ii) There is no pitch control force
reversal during a pushover maneuver
down to 0.5 g load factor.
I 12. Amend § 25.207 by revising
paragraph (b); redesignating paragraphs
(e) and (f) as paragraphs (f) and (g)
respectively; adding a new paragraph
(e); revising redesignated paragraph (f)
and adding paragraph (h) to read as
follows:
§ 25.207
Stall warning.
mstockstill on PROD1PC66 with RULES2
*
*
*
*
*
(b) The warning must be furnished
either through the inherent aerodynamic
qualities of the airplane or by a device
that will give clearly distinguishable
indications under expected conditions
of flight. However, a visual stall warning
device that requires the attention of the
crew within the cockpit is not
acceptable by itself. If a warning device
is used, it must provide a warning in
each of the airplane configurations
prescribed in paragraph (a) of this
section at the speed prescribed in
paragraphs (c) and (d) of this section.
Except for the stall warning prescribed
in paragraph (h)(2)(ii) of this section, the
stall warning for flight in icing
conditions prescribed in paragraph (e)
of this section must be provided by the
same means as the stall warning for
flight in non-icing conditions.
*
*
*
*
*
(e) In icing conditions, the stall
warning margin in straight and turning
flight must be sufficient to allow the
pilot to prevent stalling (as defined in
§ 25.201(d)) when the pilot starts a
recovery maneuver not less than three
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18:59 Aug 07, 2007
Jkt 211001
seconds after the onset of stall warning.
When demonstrating compliance with
this paragraph, the pilot must perform
the recovery maneuver in the same way
as for the airplane in non-icing
conditions. Compliance with this
requirement must be demonstrated in
flight with the speed reduced at rates
not exceeding one knot per second,
with—
(1) The more critical of the takeoff ice
and final takeoff ice accretions defined
in appendix C for each configuration
used in the takeoff phase of flight;
(2) The en route ice accretion defined
in appendix C for the en route
configuration;
(3) The holding ice accretion defined
in appendix C for the holding
configuration(s);
(4) The approach ice accretion
defined in appendix C for the approach
configuration(s); and
(5) The landing ice accretion defined
in appendix C for the landing and goaround configuration(s).
(f) The stall warning margin must be
sufficient in both non-icing and icing
conditions to allow the pilot to prevent
stalling when the pilot starts a recovery
maneuver not less than one second after
the onset of stall warning in slow-down
turns with at least 1.5 g load factor
normal to the flight path and airspeed
deceleration rates of at least 2 knots per
second. When demonstrating
compliance with this paragraph for
icing conditions, the pilot must perform
the recovery maneuver in the same way
as for the airplane in non-icing
conditions. Compliance with this
requirement must be demonstrated in
flight with—
(1) The flaps and landing gear in any
normal position;
(2) The airplane trimmed for straight
flight at a speed of 1.3 VSR; and
(3) The power or thrust necessary to
maintain level flight at 1.3 VSR.
*
*
*
*
*
(h) For flight in icing conditions
before the ice protection system has
been activated and is performing its
intended function, the following
requirements apply, with the ice
accretion defined in appendix C, part
II(e):
(1) If activating the ice protection
system depends on the pilot seeing a
specified ice accretion on a reference
surface (not just the first indication of
icing), the requirements of this section
apply, except for paragraphs (c) and (d)
of this section.
(2) For other means of activating the
ice protection system, the stall warning
margin in straight and turning flight
must be sufficient to allow the pilot to
PO 00000
Frm 00014
Fmt 4701
Sfmt 4700
prevent stalling without encountering
any adverse flight characteristics when
the speed is reduced at rates not
exceeding one knot per second and the
pilot performs the recovery maneuver in
the same way as for flight in non-icing
conditions.
(i) If stall warning is provided by the
same means as for flight in non-icing
conditions, the pilot may not start the
recovery maneuver earlier than one
second after the onset of stall warning.
(ii) If stall warning is provided by a
different means than for flight in nonicing conditions, the pilot may not start
the recovery maneuver earlier than 3
seconds after the onset of stall warning.
Also, compliance must be shown with
§ 25.203 using the demonstration
prescribed by § 25.201, except that the
deceleration rates of § 25.201(c)(2) need
not be demonstrated.
I 13. Amend § 25.237 by revising
paragraph (a) to read as follows:
§ 25.237
Wind velocities.
(a) For land planes and amphibians,
the following applies:
(1) A 90-degree cross component of
wind velocity, demonstrated to be safe
for takeoff and landing, must be
established for dry runways and must be
at least 20 knots or 0.2 VSR0, whichever
is greater, except that it need not exceed
25 knots.
(2) The crosswind component for
takeoff established without ice
accretions is valid in icing conditions.
(3) The landing crosswind component
must be established for:
(i) Non-icing conditions, and
(ii) Icing conditions with the landing
ice accretion defined in appendix C.
*
*
*
*
*
I 14. Amend § 25.253 by revising
paragraph (b), and adding a new
paragraph (c) to read as follows:
§ 25.253
High-speed characteristics.
*
*
*
*
*
(b) Maximum speed for stability
characteristics. VFC/MFC. VFC/MFC is the
maximum speed at which the
requirements of §§ 25.143(g), 25.147(E),
25.175(b)(1), 25.177, and 25.181 must be
met with flaps and landing gear
retracted. Except as noted in § 25.253(c),
VFC/MFC may not be less than a speed
midway between VMO/MMO and VDF/
MDF, except that for altitudes where
Mach number is the limiting factor, MFC
need not exceed the Mach number at
which effective speed warning occurs.
(c) Maximum speed for stability
characteristics in icing conditions. The
maximum speed for stability
characteristics with the ice accretions
defined in appendix C, at which the
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Federal Register / Vol. 72, No. 152 / Wednesday, August 8, 2007 / Rules and Regulations
requirements of §§ 25.143(g), 25.147(e),
25.175(b)(1), 25.177, and 25.181 must be
met, is the lower of:
(1) 300 knots CAS;
(2) VFC; or
(3) A speed at which it is
demonstrated that the airframe will be
free of ice accretion due to the effects of
increased dynamic pressure.
I 15. Amend § 25.773 by revising
paragraph (b)(1)(ii) to read as follows:
§ 25.773
Pilot compartment view.
*
*
*
*
*
(b) * * *
(1) * * *
(i) * * *
(ii) The icing conditions specified in
§ 25.1419 if certification for flight in
icing conditions is requested.
*
*
*
*
*
I 16. Amend § 25.941 by revising
paragraph (c) to read as follows:
§ 25.941 Inlet, engine, and exhaust
compatibility.
*
*
*
*
*
(c) In showing compliance with
paragraph (b) of this section, the pilot
strength required may not exceed the
limits set forth in § 25.143(d), subject to
the conditions set forth in paragraphs (e)
and (f) of § 25.143.
I 17. Amend § 25.1419 by revising the
introductory text to read as follows:
§ 25.1419
Ice protection.
If the applicant seeks certification for
flight in icing conditions, the airplane
must be able to safely operate in the
continuous maximum and intermittent
maximum icing conditions of appendix
C. To establish this—
*
*
*
*
*
I 18. Amend appendix C to part 25 by
adding a part I heading and a new
paragraph (c) to part I; and adding a new
part II to read as follows:
Appendix C of Part 25
mstockstill on PROD1PC66 with RULES2
Part I—Atmospheric Icing Conditions
(a) * * *
(c) Takeoff maximum icing. The maximum
intensity of atmospheric icing conditions for
takeoff (takeoff maximum icing) is defined by
the cloud liquid water content of 0.35 g/m3,
the mean effective diameter of the cloud
VerDate Aug<31>2005
18:59 Aug 07, 2007
Jkt 211001
droplets of 20 microns, and the ambient air
temperature at ground level of minus 9
degrees Celsius (-9( C). The takeoff maximum
icing conditions extend from ground level to
a height of 1,500 feet above the level of the
takeoff surface.
Part II—Airframe Ice Accretions for
Showing Compliance With Subpart B.
(a) Ice accretions—General. The most
critical ice accretion in terms of airplane
performance and handling qualities for each
flight phase must be used to show
compliance with the applicable airplane
performance and handling requirements in
icing conditions of subpart B of this part.
Applicants must demonstrate that the full
range of atmospheric icing conditions
specified in part I of this appendix have been
considered, including the mean effective
drop diameter, liquid water content, and
temperature appropriate to the flight
conditions (for example, configuration,
speed, angle-of-attack, and altitude). The ice
accretions for each flight phase are defined
as follows:
(1) Takeoffice is the most critical ice
accretion on unprotected surfaces and any
ice accretion on the protected surfaces
appropriate to normal ice protection system
operation, occurring between liftoff and 400
feet above the takeoff surface, assuming
accretion starts at liftoff in the takeoff
maximum icing conditions of part I,
paragraph (c) of this appendix.
(2) Final takeoff ice is the most critical ice
accretion on unprotected surfaces, and any
ice accretion on the protected surfaces
appropriate to normal ice protection system
operation, between 400 feet and either 1,500
feet above the takeoff surface, or the height
at which the transition from the takeoff to the
en route configuration is completed and VFTO
is reached, whichever is higher. Ice accretion
is assumed to start at liftoff in the takeoff
maximum icing conditions of part I,
paragraph (c) of this appendix.
(3) En route ice is the critical ice accretion
on the unprotected surfaces, and any ice
accretion on the protected surfaces
appropriate to normal ice protection system
operation, during the en route phase.
(4) Holding ice is the critical ice accretion
on the unprotected surfaces, and any ice
accretion on the protected surfaces
appropriate to normal ice protection system
operation, during the holding flight phase.
(5) Approach ice is the critical ice
accretion on the unprotected surfaces, and
any ice accretion on the protected surfaces
appropriate to normal ice protection system
operation following exit from the holding
flight phase and transition to the most critical
approach configuration.
PO 00000
Frm 00015
Fmt 4701
Sfmt 4700
44669
(6) Landing ice is the critical ice accretion
on the unprotected surfaces, and any ice
accretion on the protected surfaces
appropriate to normal ice protection system
operation following exit from the approach
flight phase and transition to the final
landing configuration.
(b) In order to reduce the number of ice
accretions to be considered when
demonstrating compliance with the
requirements of § 25.21(g), any of the ice
accretions defined in paragraph (a) of this
section may be used for any other flight
phase if it is shown to be more critical than
the specific ice accretion defined for that
flight phase. Configuration differences and
their effects on ice accretions must be taken
into account.
(c) The ice accretion that has the most
adverse effect on handling qualities may be
used for airplane performance tests provided
any difference in performance is
conservatively taken into account.
(d) For both unprotected and protected
parts, the ice accretion for the takeoff phase
may be determined by calculation, assuming
the takeoff maximum icing conditions
defined in appendix C, and assuming that:
(1) Airfoils, control surfaces and, if
applicable, propellers are free from frost,
snow, or ice at the start of the takeoff;
(2) The ice accretion starts at liftoff;
(3) The critical ratio of thrust/power-toweight;
(4) Failure of the critical engine occurs at
VEF; and
(5) Crew activation of the ice protection
system is in accordance with a normal
operating procedure provided in the Airplane
Flight Manual, except that after beginning the
takeoff roll, it must be assumed that the crew
takes no action to activate the ice protection
system until the airplane is at least 400 feet
above the takeoff surface.
(e) The ice accretion before the ice
protection system has been activated and is
performing its intended function is the
critical ice accretion formed on the
unprotected and normally protected surfaces
before activation and effective operation of
the ice protection system in continuous
maximum atmospheric icing conditions. This
ice accretion only applies in showing
compliance to §§ 25.143(j) and 25.207(h).
Issued in Washington, DC, on July 25,
2007.
Marion C. Blakey,
Administrator.
[FR Doc. E7–14937 Filed 8–7–07; 8:45 am]
BILLING CODE 4910–13–P
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Agencies
[Federal Register Volume 72, Number 152 (Wednesday, August 8, 2007)]
[Rules and Regulations]
[Pages 44656-44669]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E7-14937]
[[Page 44655]]
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Part III
Department of Transportation
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Federal Aviation Administration
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14 CFR Part 25
Airplane Performance and Handling Qualities in Icing Conditions; Final
Rule
Federal Register / Vol. 72 , No. 152 / Wednesday, August 8, 2007 /
Rules and Regulations
[[Page 44656]]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA-2005-22840; Amendment No. 25-121]
RIN 2120-AI14
Airplane Performance and Handling Qualities in Icing Conditions
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
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SUMMARY: This action introduces new airworthiness standards to evaluate
the performance and handling characteristics of transport category
airplanes in icing conditions. This action will improve the level of
safety for new airplane designs when operating in icing conditions, and
harmonizes the U.S. and European airworthiness standards for flight in
icing conditions.
DATES: This final rule becomes effective October 9, 2007.
FOR FURTHER INFORMATION CONTACT: Don Stimson, FAA, Airplane & Flight
Crew Interface Branch, ANM-111, Transport Airplane Directorate,
Aircraft Certification Service, 1601 Lind Avenue SW., Renton,
Washington 98057-3356; telephone: (425) 227-1129; fax: (425) 227-1149,
e-mail: don.stimson@faa.gov.
SUPPLEMENTARY INFORMATION:
Availability of Rulemaking Documents
You can get an electronic copy using the Internet by:
(1) Searching the Department of Transportation's electronic Docket
Management System (DMS) Web page (https://dms.dot.gov/search);
(2) Visiting the FAA's Regulations and Policies Web page at https://
www.faa.gov/regulations_policies; or
(3) Accessing the Government Printing Office's Web page at https://
www.gpoaccess.gov/fr/.
You can also get a copy by sending a request to the Federal
Aviation Administration, Office of Rulemaking, ARM-1, 800 Independence
Avenue SW., Washington, DC 20591, or by calling (202) 267-9680. Make
sure to identify the docket number or amendment number of this
rulemaking.
Anyone is able to search the electronic form of all comments
received into any of our dockets by the name of the individual
submitting the comment (or signing the comment, if submitted on behalf
of an association, business, labor union, etc.). You may review DOT's
complete Privacy Act statement in the Federal Register published on
April 11, 2000 (Volume 65, Number 70; Pages 19477-78) or you may visit
https://dms.dot.gov.
Small Business Regulatory Enforcement Fairness Act
The Small Business Regulatory Enforcement Fairness Act (SBREFA) of
1996 requires the FAA to comply with small entity requests for
information or advice about compliance with statutes and regulations
within its jurisdiction. If you are a small entity and you have a
question regarding this document, you may contact a local FAA official,
or the person listed under FOR FURTHER INFORMATION CONTACT. You can
find out more about SBREFA on the Internet at https://www.faa.gov/
regulations_policies/rulemaking/sbre_act/.
Authority for This Rulemaking
The FAA's authority to issue rules regarding aviation safety is
found in Title 49 of the United States Code. Subtitle I, Section 106
describes the authority of the FAA Administrator. Subtitle VII,
Aviation Programs, describes in more detail the scope of the agency's
authority.
This rulemaking is promulgated under the authority described in
Subtitle VII, Part A, Subpart III, Section 44701, ``General
requirements.'' Under that section, the FAA is charged with promoting
safe flight of civil aircraft in air commerce by prescribing minimum
standards required in the interest of safety for the design and
performance of aircraft. This regulation is within the scope of that
authority because it prescribes new safety standards for the design of
transport category airplanes.
I. Background
A. Statement of the Problem
Currently, Sec. 25.1419, ``Ice protection,'' requires transport
category airplanes with approved ice protection features be capable of
operating safely within the icing conditions identified in appendix C
of part 25. This section requires applicants to perform flight testing
and conduct analyses to make this determination. Section 25.1419 only
requires an applicant to demonstrate that the airplane can operate
safely in icing conditions if the applicant is seeking to certificate
ice protection features.
Although an airplane's performance capability and handling
qualities are important in determining whether an airplane can operate
safely, part 25 does not have specific requirements on airplane
performance or handling qualities for flight in icing conditions. In
addition, the FAA does not have a standard set of criteria defining
what airplane performance capability and handling qualities are needed
to be able to operate safely in icing conditions. Finally, Sec.
25.1419 fails to address certification approval for flight in icing
conditions for airplanes without ice protection features.
Service history shows that flight in icing conditions may be a
safety risk for transport category airplanes. We found nine accidents
since 1983 in the National Transportation Safety Board's accident
database that may have been prevented if this rule had been in effect.
In evaluating the potential for this rulemaking to avoid future
accidents, we considered only past accidents involving tailplane stall
or potential airframe ice accretion effects on drag or controllability.
We did not consider accidents related to ground deicing since this
amendment does not change the ground deicing requirements. We also
limited our search to accidents involving aircraft certificated to the
icing standards of part 25 (or its predecessor).
B. NTSB Recommendations
This amendment addresses the following National Transportation
Safety Board (NTSB) safety recommendations related to airframe
icing:\1\
---------------------------------------------------------------------------
\1\ Refer to appendix 3 of the NPRM for more details on these
safety recommendations (except for A-96-056, which was not discussed
in the NPRM).
---------------------------------------------------------------------------
1. NTSB Safety Recommendation A-91-087 \2\ recommended requiring
flight tests where ice is accumulated in those cruise and approach flap
configurations in which extensive exposure to icing conditions can be
expected, and requiring subsequent changes in configuration to include
landing flaps. This safety recommendation resulted from an accident
that was attributed to tailplane stall due to ice contamination.
---------------------------------------------------------------------------
\2\ ``Effect of Ice on Aircraft Handling Characteristics (1984
Trials),'' Jetstream 31--G-JSSD, British Aerospace Flight Test
Report FTR.177/JM, dated May 13, 1985.
---------------------------------------------------------------------------
This amendment requires applicants to investigate the
susceptibility of airplanes to ice-contaminated tailplane stall during
airworthiness certification. An accompanying Advisory Circular (AC)
will provide detailed guidance on acceptable means of compliance,
including flight tests in icing conditions where the airplane's
configuration is changed from flaps and landing gear retracted to flaps
and landing gear in the landing position.
[[Page 44657]]
2. NTSB Safety Recommendation A-96-056 \3\ recommended revising the
icing certification testing regulation to ensure that airplanes are
properly tested for all conditions in which they are authorized to
operate, or are otherwise shown to be capable of safe flight into such
conditions. Additionally, if safe operations cannot be demonstrated by
the manufacturer, operational limitations should be imposed to prohibit
flight in such conditions and flightcrews should be provided with the
means to positively determine when they are in icing conditions that
exceed the limits for aircraft certification.
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\3\ National Transportation Safety Board, 1996. ``In-Flight
Icing Encounter and Loss of Control, Simmons Airlines,
d.b.a.American Eagle Flight 4184, Avions de Transport Regional (ATR)
Model 72-212, N401AM, Roselawn, Indiana, October 31, 1994.''
Aircraft Accident Report NTSB/AAR-96/01. Washington, DC.
---------------------------------------------------------------------------
This amendment partially addresses safety recommendation A-96-056
by revising the certification standards to ensure that transport
category airplanes are properly tested for the critical icing
conditions defined in appendix C of part 25. We are considering future
rulemaking action to address icing conditions beyond those covered by
appendix C of part 25, and to provide flightcrews with a means to
positively determine when they are in icing conditions that exceed the
limits for aircraft certification.
3. NTSB Safety Recommendation A-98-094 \4\ recommended that
manufacturers of all turbine-engine driven airplanes (including the
EMB-120) provide minimum maneuvering airspeed information for all
airplane configurations, phases, and conditions of flight (icing and
non-icing conditions). Also, the NTSB recommended that minimum
airspeeds should take into consideration the effects of various types,
amounts, and locations of ice accumulations, including thin amounts of
very rough ice, ice accumulated in supercooled large droplet icing
conditions, and tailplane icing.
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\4\ National Transportation Safety Board, 1998. ``In-Flight
Icing Encounter and Uncontrolled Collision With Terrain, Comair
Flight 3272, Embraer EMB-120RT, N265CA, Monroe, Michigan, January 9,
1997.'' Aircraft Accident Report NTSB/AR-98/04. Washington, DC.
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This amendment partially addresses safety recommendation A-98-094
by requiring the same maneuvering capability requirements at the
minimum operating speeds in the most critical icing conditions defined
in appendix C of part 25 as are currently required in non-icing
conditions. We are considering future rulemaking action to address
supercooled large droplet icing conditions.
4. NTSB Safety Recommendation A-98-096 is also a result of the same
accident discussed under Safety Recommendation A-98-094, above. The
NTSB recommended the FAA require, during type certification, that
manufacturers and operators of all transport category airplanes
certificated to operate in icing conditions install stall warning/
protection systems that provide a cockpit warning (aural warning and/or
stick shaker) before the onset of stall when the airplane is operating
in icing conditions.
This amendment requires adequate stall warning margin to be shown
with the most critical ice accretion for transport category airplanes
approved to fly in icing conditions. Except for the short time before
icing conditions are recognized and the ice protection system
activated, this stall warning must be provided by the same means as for
non-icing conditions. Although neither an aural stall warning or stick
shaker is required under this amendment, all recently certificated
transport category airplanes have used either a stick shaker or an
aural warning to warn the pilot of an impending stall. We do not
anticipate any future transport category airplane designs without a
cockpit warning of an impending stall.
C. Summary of the NPRM
This amendment is based on the notice of proposed rulemaking
(NPRM), Notice No. 05-10, which was published in the Federal Register
on November 4, 2005 (70 FR 67278). In the NPRM, we proposed to revise
the airworthiness standards for type certification of transport
category airplanes to add a comprehensive set of new requirements for
airplane performance and handling qualities for flight in icing
conditions. We also proposed to add requirements that define the ice
accretion (that is, the size, shape, location, and texture of the ice)
that must be considered for each phase of flight.
These changes were proposed to ensure that minimum operating speeds
determined during certification of all future transport category
airplanes will provide adequate maneuver capability in icing conditions
for all phases of flight and all airplane configurations. They would
also harmonize the FAA's regulations with those expected to be adopted
by the European Aviation Safety Agency (EASA). This harmonization would
not only benefit the aviation industry economically, but also maintain
the necessary high level of aviation safety.
II. Discussion of the Final Rule
A. General Summary
Twelve commenters responded to the NPRM: Four private citizens,
Airbus Industrie (Airbus), the Air Line Pilots Association (ALPA), The
Boeing Company (Boeing), Dassault Aviation (Dassault), the General
Aviation Manufacturers Association (GAMA), the National Transportation
Safety Board (NTSB), Raytheon Aircraft Company (Raytheon), and the
United Kingdom Civil Aviation Authority (U.K. CAA).
Seven of these commenters explicitly expressed support for the
rule, none opposed it. Many of the commenters suggested specific
improvements or clarifications. Summaries of their comments and our
responses (including explanations of changes to the final rule in
response to the comments) are provided below.\5\
---------------------------------------------------------------------------
\5\ The full text of each commenter's submission is available in
the Docket.
---------------------------------------------------------------------------
1. Engine Bleed Configuration for Showing Compliance With Sec. 25.119
The proposed Sec. 25.119 would require applicants to comply with
the landing climb performance requirements in both icing and non-icing
conditions. Raytheon stated that proposed Sec. 25.119(b) is unclear as
to whether the engine bleed configuration for showing compliance should
include bleed extraction for operation of the airframe and engine ice
protection systems (IPS). Raytheon pointed out that engine bleed
extraction for operating the airframe and engine IPS could affect
engine acceleration time, which would affect the thrust level used for
showing compliance. Raytheon noted that the means of compliance in the
proposed AC addresses this issue, but recommended that it be clarified
within the rule.
While we agree that engine bleed extraction could affect the thrust
level used to show compliance with Sec. 25.119(b), we disagree that
the rule needs to be revised to state the bleed configuration. For
flight in icing conditions, Sec. 25.21(g)(1) requires compliance to be
shown assuming normal operation of the airplane and its IPS in
accordance with the operating limitations and operating procedures
established by the applicant and provided in the Airplane Flight Manual
(AFM). The bleed configuration of the engines would be part of the AFM
operating procedures that must be used to show compliance with Sec.
25.119(b). As noted by Raytheon, the guidance provided in the AC
accompanying this final rule reminds applicants that the
[[Page 44658]]
engine bleed configuration should be considered when showing compliance
with the requirements of this final rule.
2. Using the Landing Ice Accretion To Comply With Sec.
25.121(d)(2)(ii)
Boeing proposed using the landing ice accretion for showing
compliance with the approach climb gradient requirement in icing
conditions, rather than the holding ice accretion as proposed in Sec.
25.121(d)(2)(ii). Boeing recommended this change to harmonize with
EASA's proposed rule.
We consider it inappropriate to use the landing ice accretion for
compliance with Sec. 25.121(d). Section 25.121(d) specifies the
minimum climb capability, in terms of a climb gradient, that an
airplane must be capable of achieving in the approach configuration
with one engine inoperative. This requirement involves the approach
phase of flight, which occurs before entering the landing phase.
Depending on the IPS design and the procedures for its use, the landing
ice accretion (which is defined as the ice accretion after exiting the
holding phase and transitioning to the landing phase) may be smaller
than the holding ice accretion. For example, there may be a procedure
to use the IPS to remove the ice when transitioning to the landing
phase so that the protected areas are clear of ice for landing. It
would be inappropriate to allow any reduction in the ice accretion to
be used for the approach climb gradient (in the approach phase)
resulting from using the IPS in the landing phase.
We note that neither EASA's Notice of Proposed Amendment (NPA)
covering the same icing-related safety issues (NPA 16/2004) nor our
NPRM define an ice accretion specific to the approach phase of flight.
Both proposals used holding ice for compliance in icing conditions
because holding ice was considered to be conservative for this flight
phase. Therefore, we believe that it is appropriate to define an
additional ice accretion that would be specifically targeted at the
approach phase of flight. We have added the following definition as
paragraph (a)(5) in part II of appendix C:
``Approach ice is the critical ice accretion on the unprotected
parts of the airplane, and any ice accretion on the protected parts
appropriate to normal IPS operation following exit from the holding
flight phase and transition to the most critical approach
configuration.''
Section 25.121(d)(2)(ii) is also revised to refer to this
definition. The definition of landing ice is revised to be the ice
accretion after exiting from the approach phase (rather than after the
holding phase as proposed) and redesignated as paragraph (a)(6).
Finally, applicants would still have the option to use a more
conservative ice accretion in accordance with paragraph (b) of part II
of appendix C. Therefore, applicants would have the option of using the
holding ice accretion as proposed in the NPRM if it was more critical
than the approach ice accretion.
3. VREF Comparison at Maximum Landing Weight
Proposed Sec. 25.125(a)(2) would require landing distances to be
determined in icing conditions if the landing approach speed,
VREF, for icing conditions exceeds VREF for non-
icing conditions by more than 5 knots calibrated airspeed. Boeing
proposed that the VREF speed comparison for icing and non-
icing conditions in proposed Sec. 25.125(a)(2) be made at the maximum
landing weight. This proposal would harmonize the FAA's rule with the
expected EASA final rule. Boeing also stated that the proposed rule was
deficient in that it did not specify the weight or weights at which
this comparison must be made. The results of this comparison can depend
on the weight at which the comparison is made.
We agree that this comparison should be made at the maximum landing
weight and have revised Sec. 25.125(a)(2) of the final rule
accordingly. We consider this to be a clarifying change that will not
impose an additional burden on applicants.
4. Landing Distance in Icing Conditions
As noted in the discussion of the previous comment, proposed Sec.
25.125(a)(2) would require the landing distance to be determined in
icing conditions if the landing approach speed, VREF, for
icing conditions exceeds the non-icing VREF by more than 5
knots calibrated airspeed. An increase in VREF for icing
conditions is normally caused by an increase in stall speed in icing
conditions because VREF must be at least 1.23 times the
stall speed.
Raytheon noted that a change in stall speed is not the only factor
that might affect landing distance in icing conditions. For example,
idle thrust might be adjusted by an engine control system designed to
maintain sufficient bleed flow to support the demands of engine and
airframe ice protection. Also, landing procedures for icing conditions
might be different than for non-icing conditions. Raytheon suggested
revising proposed Sec. 25.125(a)(2) to require that the landing
distance must also be determined in icing conditions if the thrust
settings or landing procedures used in icing conditions would cause an
increase in the landing distance.
One of the primary safety concerns addressed by proposed Sec.
25.125 is to maintain a minimum speed margin above the stall speed for
an approach and landing in icing conditions. This is achieved by
increasing the landing approach speed (VREF) if ice on the
airplane results in a significant increase in stall speed. Under
proposed Sec. 25.125(b)(2)(ii)(B), a significant increase in stall
speed relative to this requirement is one that results in an increase
in VREF of more than 5 knots calibrated airspeed, where
VREF is not less than 1.23 times the stall speed.
An increase in VREF will increase the distance required
by the airplane to land and come to a stop since the airplane will
touch down at a higher speed. A significant increase in stall speed in
the landing configuration due to ice has a secondary effect of
increasing the required landing distance. We proposed in Sec.
25.125(a)(2) that this increase in landing distance be taken into
account. Proposed Sec. 25.125(a)(2) resulted from the secondary effect
of a significant increase in stall speed in the landing configuration
due to ice, not to an evaluation of all of the possible reasons why the
required landing distance may need to be longer in icing conditions.
The commenter correctly points out that a longer landing distance may
also be needed if higher thrust settings or different landing
procedures are used in icing conditions.
In evaluating the potential costs and effects of the proposed
change, we could not find any existing airplanes where, if the
requirement proposed by the commenter had been in effect, it would have
required an applicant to determine a longer landing distance in icing
conditions. In nearly all cases, applicants have not used different
thrust or power settings or different procedures for landing in icing
conditions. Airplane manufacturers indicated that they did not
anticipate this relationship to change for future designs.
When different thrust or power settings or procedures have been
used for landing in icing conditions, VREF has also
increased by more than 5 knots. In these cases, applicants would be
required by the proposed Sec. 25.125(a) to determine the landing
distance for icing conditions, and existing Sec. 25.101(c) and (f)
require applicants to include the effects of different power or thrust
settings or landing procedures on this landing distance.
[[Page 44659]]
Therefore, we see no need to amend the proposed requirement as
recommended by Raytheon.
5. Sandpaper Ice Accretion
Proposed appendix C, part II(a)(6) defined sandpaper ice as a thin,
rough layer of ice. A private citizen notes the NPRM did not
specifically state how sandpaper ice should be used or considered in
showing compliance with any of the proposed airplane performance and
handling qualities requirements. This commenter suggested amending
proposed Sec. 25.143(i)(1) to add that if normal operation of the
horizontal tail IPS allows ice to form on the tail leading edge,
sandpaper ice must also be considered in determining the critical ice
accretion. (Proposed Sec. 25.143(i)(1) would require applicants to
demonstrate the airplane is safely controllable, per the applicable
requirements of Sec. 25.143, with the ice accretion defined in
appendix C that is most critical for the particular flight phase.)
Appendix C, part II(a) requires applicants to use the most critical
ice accretion to show compliance with the applicable subpart B airplane
performance and handling requirements in icing conditions. The
determination of the most critical ice accretion must consider the full
range of atmospheric icing conditions of part I of appendix C as well
as the characteristics of the IPS (per Sec. 25.21(g)(1) and appendix
C, part II(a)). This includes consideration of thin, rough layers of
ice (known as sandpaper ice) as well as any other type of ice accretion
that may occur in the applicable atmospheric icing conditions, taking
into account the operating characteristics of the IPS and the flight
phase.
Since the requirement to use the most critical ice accretion
includes consideration of sandpaper ice and sandpaper ice is not
referenced elsewhere in the rule, we have removed appendix C, part
II(a)(6) from the final rule. The AC that we are issuing along with
this final rule, or shortly thereafter, provides further information on
the use of sandpaper ice in showing compliance. (This AC will be
available in the Regulatory Guidance Library (RGL) when issued.)
6. Critical Ice Accretion for Showing Compliance With Sec.
25.143(i)(1)
As noted in the discussion of the previous comment, proposed Sec.
25.143(i)(1) would require applicants to demonstrate the airplane is
safely controllable, per the applicable requirements of Sec. 25.143,
with the ice accretion defined in appendix C that is most critical for
the particular flight phase. Raytheon stated that because ice accretion
before normal system operation is addressed separately in Sec.
25.143(j), the controllability demonstration required by Sec.
25.143(i)(1) should be limited to only the most critical ice accretion
defined in appendix C part II(a) rather than all of appendix C.
For purposes of the controllability demonstrations required by
Sec. 25.143(i)(1), appendix C, parts I and II(a), (b), (c), and (d)
apply. Appendix C, part II(e) only applies to Sec. Sec. 25.143(j) and
25.207(h), which are the only subpart B requirements pertaining to
flight in icing conditions before activation of the IPS. We acknowledge
that this limited applicability of appendix C, part II(e) is unclear in
the language proposed, and we have revised the final rule to include a
sentence that specifies this limitation.
7. Pushover Maneuver for Ice-Contaminated Tailplane Stall Evaluation
Raytheon stated that proposed Sec. 25.143(i)(2), which states that
a push force from the pilot must be required throughout a pushover
maneuver down to zero g or full down elevator, is inconsistent with
allowing a pull force for recovery from the maneuver. Raytheon noted
that the FAA stated in the NPRM that a force reversal (that is, a push
force becoming a pull force) is unacceptable, implying that the pilot
should only be permitted to relax his or her push force to initiate
recovery. The 50-pound limit for recovery in the proposed Sec.
25.143(i)(2) appears to allow up to 50 pounds of force reversal to
develop during the maneuver, including at the initiation of recovery
from the maneuver. Raytheon stated that they object to the proposed
requirement and continue to support the industry proposal for the
pushover maneuver submitted to ARAC by the Flight Test Harmonization
Working Group. The industry proposal specified there must be no force
reversal down to 0.5 g (the limit of the operational flight envelope)
and a prompt recovery from zero g (or full down elevator control if
zero g cannot be obtained) with less than 50 pounds of stick force.
Raytheon stated that the 50-pound pull force was not intended as a
limit for the subsequent pull-up maneuver during recovery from the
push-over test.
The FAA continues to disagree with the industry proposal, and
Raytheon did not offer any new evidence or rationale that would lead us
to reconsider our position. As stated in the NPRM, certification
testing and service experience have shown that testing to only 0.5 g is
inadequate, considering the relatively high frequency of experiencing
0.5 g in operations. Since the beginning of the 1980s, the practice of
many certification authorities has been to require testing to lower
load factors. The industry proposal for determining the acceptability
of a control force reversal (as described in the NPRM) was subjective
and would have led to inconsistent evaluations. Requiring a push force
to zero g removes subjectivity in the assessment of the airplane's
controllability and provides readily understood criteria of
acceptability. Any lesser standard would not give confidence that the
problem has been fully addressed.
We do not consider the requirement for a push force to be needed to
reach zero g, coupled with allowing a pull force of up to 50 pounds
during the recovery, to be inconsistent with our position that force
reversals are unacceptable within the normal flight envelope. The
pushover maneuver ends when zero g is reached (or when full down
elevator is achieved if zero g cannot be reached). The recovery is a
separate pull-up maneuver, initiated by the pilot, to regain the
original flight path. It is acceptable for this maneuver to require a
pull force, but the pull force must not exceed 50 pounds, which is the
maximum pitch force permitted by the existing Sec. 25.143(c)
(renumbered as Sec. 25.143(d) by this amendment) for short term
application of force using one hand. No changes were made.
8. Pushover Maneuver Limited by Design Features Other Than Elevator
Power
Airbus noted that proposed Sec. 25.143(i)(2) would allow the
required pushover maneuver to end before zero g is reached if the
airplane is limited by elevator power. Airbus commented that safe
design characteristics other than limited elevator power may also
prevent an aircraft from reaching zero g during the pushover maneuver
(e.g., flight envelope protections designed into fly-by-wire control
systems). Airbus proposed revising the proposed rule to allow the
pushover maneuver to end before reaching zero g for other safe design
characteristics that prevent reaching zero g.
We agree with Airbus and have revised Sec. 25.143(i)(2) to include
consideration of other design characteristics of the flight control
system that may prevent reaching zero g in the pushover maneuver.
[[Page 44660]]
9. Pitch Force Requirements During a Sideslip Maneuver
Raytheon stated that the proposed requirement for flight in icing
conditions is more stringent than the requirements applicable to non-
icing conditions. Proposed Sec. 25.143(i)(3) would require that any
changes in force that the pilot must apply to the pitch control to
maintain speed with increasing sideslip angle must be steadily
increasing with no force reversals. Raytheon notes the non-icing
subpart B static lateral-directional stability requirements of Sec.
25.177 do not specify that the pitch forces cannot reverse. For
example, a push force at small sideslip angles that changes to a pull
force as sideslip increases is acceptable.
Raytheon noted that it would not be unusual for an airplane to
require an increase in pull force with increasing sideslip. If the
tailplane or a portion of it developed aerodynamic separation as
sideslip increases, then to maintain 1-g flight the elevator hinge
moment would require further pull force that could be sudden or become
excessive. Raytheon notes this undesirable characteristic would comply
with proposed Sec. 25.143(i)(3).
Raytheon and another commenter (a private citizen) proposed that
the proposed rule be revised to eliminate the requirements that the
pitch force be steadily increasing with increasing sideslip and that
there be no reversal. Instead, these commenters suggested that the
requirement should be limited to ensuring that there is no abrupt or
uncontrollable pitching tendency.
The FAA agrees with the commenters that small, gradual changes in
the pitch control force may not be objectionable or unsafe, and that
the proposed requirement is unnecessarily more stringent than the
requirements for non-icing conditions. The safety concern is sudden or
large pitch force changes that would be difficult for the pilot to
control. Therefore, we have changed Sec. 25.143(i)(3) in the final
rule to read as follows:
``Any changes in force that the pilot must apply to the pitch
control to maintain speed with increasing sideslip angle must be
steadily increasing with no force reversals, unless the change in
control force is gradual and easily controllable by the pilot without
using exceptional piloting skill, alertness, or strength.''
Under this new language, abrupt changes in the control force
characteristic, unless so small as to be unnoticeable, would not be
considered to meet the requirement that the force be steadily
increasing. A gradual change in control force is a change that is not
abrupt and does not have a steep gradient. It can be easily managed by
a pilot of average skill, alertness, and strength. Control forces in
excess of those permitted by Sec. 25.143(d) would be considered
excessive.
10. Stall Warning in Icing Conditions
Existing Sec. 25.207(c) requires at least a 3 knot or 3% speed
margin between the stall warning speed (VSW) and the
reference stall speed (VSR). Existing Sec. 25.207(d)
requires at least a 5 knot or 5% speed margin between VSW
and the speed at which the behavior of the airplane gives the pilot a
clear and distinctive indication of an acceptable nature that the
airplane is stalled. Under proposed Sec. 25.21(g), the stall warning
requirements of Sec. 25.207(c) and (d) would apply only to non-icing
conditions. For icing conditions, proposed Sec. 25.207(e) requires
that stall warning be sufficient to allow the pilot to prevent stalling
when the pilot starts the recovery maneuver not less than 3 seconds
after the onset of stall warning in a one knot per second deceleration.
The U.K. CAA noted that proposed Sec. 25.207(e) would allow stall
warning in icing conditions to occur at a speed slower than the speed
for the maximum lift capability of the wing (also known as the 1g stall
speed). This would not be true for non-icing conditions because of
Sec. 25.207(c). According to U.K. CAA, if the stall warning speed is
slower than the 1g stall speed, the airplane will have little or no
maneuvering capability at the point that the airplane gives the pilot a
warning of an impending stall. The U.K. CAA stated that in an
operational scenario, if the airplane slows to a speed slightly above
the stall warning speed, any attempt to maneuver the airplane or
further reduce speed could lead to an immediate stall. This situation
is of most concern to the U.K. CAA in the landing phase because, unlike
the cruise or takeoff phases, there are limited options for the crew to
recover from a stall. The airplane is already at low altitude and
descending towards the ground, the power setting is low, and the
potential to trade height for speed is extremely limited.
Due to this concern, the U.K. CAA recommended making the non-icing
stall warning speed margin requirements of Sec. 25.207(c) and (d) also
apply to icing conditions, but only when the airplane is in the landing
configuration. Since the proposed Sec. 25.207(e) was intended to be
used in place of Sec. 25.207(c) and (d) for icing conditions, the U.K.
CAA suggested that, if Sec. 25.207(c) and (d) are applied to the
landing configuration in icing conditions, then Sec. 25.207(e) need
not be applied to the landing configuration.
In developing the proposed rule, the FAA accepted a determination
by the Flight Test Harmonization Working Group (FTHWG) that the same
handling qualities standards should generally apply to flight in icing
conditions as apply to flight in non-icing conditions. In certain
areas, however, the FTHWG decided that the handling qualities standards
for non-icing conditions were inappropriate for flight in icing
conditions. In these areas, the FTHWG recommended alternative criteria
for flight in icing conditions.
The stall warning margin was one of the areas where the FTHWG
recommended alternative criteria for flight in icing conditions. The
FTHWG determined that applying the existing stall warning margin
requirements of Sec. 25.207(c) and (d) to icing conditions would be
far more stringent than the best current practices and would unduly
penalize designs that have not exhibited safety problems in icing
conditions. The FTHWG further determined the stall warning requirements
of the existing Sec. 25.207(c) and (d) could be made less stringent
for icing conditions without compromising safety. As a result, we
proposed the less stringent Sec. 25.207(e) to address stall warning
margin requirements for icing conditions in place of Sec. 25.207(c)
and (d).
No changes have been made to this final rule as a result of the
U.K. CAA's comment. We acknowledge that the U.K. CAA has pointed out a
deficiency with safety implications in the proposed stall warning
requirements. However, U.S. manufacturers' initial cost analysis of the
U.K. CAA's recommended changes indicates these changes may
significantly increase the costs of this rulemaking beyond the benefits
provided due to uncertainties in how the increased stall warning margin
requirement would affect airplane type certification testing,
certification program schedules, and the design of stall warning
systems.
In addition, the U.K. CAA's recommended changes would introduce
significant regulatory differences from EASA's airworthiness
certification requirements, and might not completely resolve the
potential safety issue. For these reasons we believe that additional
time and aviation industry participation are needed to determine an
appropriate way to address this safety concern. However, we do not
believe it is appropriate to delay issuance of this final rule pending
resolution of this issue.
[[Page 44661]]
This final rule significantly improves the affected airworthiness
standards and the benefits of these improvements should be achieved as
soon as possible. It also satisfies a number of important NTSB
recommendations. As these improvements are being implemented, we will
continue to work closely with EASA and industry to address the issue
raised by the U.K. CAA. This subject has been included on EASA's 2008
rulemaking agenda, and we will work with them in that context to agree
on a harmonized approach. Once these efforts are completed, we will
initiate new rulemaking, if appropriate, to adopt any necessary
revisions to part 25.
11. Stall and Stall Warning Requirements Prior to Activation of the IPS
Proposed Sec. 25.207(h)(2)(ii) would require compliance with the
stall characteristics requirements of Sec. 25.203, using the stall
demonstration prescribed by Sec. 25.201, for flight in icing
conditions before the IPS is activated. This requirement would apply if
the stall warning required by Sec. 25.207 is provided by a different
means for flight in icing conditions than for non-icing conditions. The
stall demonstration prescribed by Sec. 25.201 requires that the
stalling maneuver be continued to the point where the airplane gives
the pilot a clear and distinctive indication of an acceptable nature
that the airplane is stalled.
Raytheon disagreed with this proposal because the ice accretion
resulting from a delay in activating the IPS is a short term transient
condition. According to Raytheon, the intent should be to demonstrate
only the ability to prevent a stall, rather than to also ensure that
the airplane has good stall characteristics. Raytheon stated that it is
unnecessary to consider that the pilot might ignore the stall buffeting
and continue to increase angle-of-attack until the airplane is stalled.
To comply with the proposed rule, Raytheon argued that an airplane with
a stick pusher stall identification system would be required to have
its stick pusher activation based on a contaminated wing leading edge
for non-icing conditions. This would require increased takeoff and
landing speeds and negatively impact all takeoff and landing
performance.
Raytheon also stated that the cost impacts would be excessive for
what is only a transient condition. Raytheon's position is that there
is no need to consider the airplane's handling qualities after it has
stalled. It should be sufficient to show that the pilot can prevent
stalling if the recovery maneuver is not begun until at least three
seconds after the onset of stall warning, which is also required by the
proposed Sec. 25.207(h)(2)(ii).
We do not agree with Raytheon's comments. Because of human factors
considerations, proposed Sec. 25.207(b) generally requires that the
same means of providing a stall warning be used in both icing and non-
icing conditions. Therefore, if a stick shaker is used for stall
warning in non-icing conditions (as is the case for most transport
category airplanes) it must also be used for stall warning in icing
conditions. The reason for this proposed requirement is that in icing
accidents and incidents where the airplane stalled before the stick
shaker activated, flightcrews have not recognized the buffeting
associated with ice contamination in time to prevent stalling. Proposed
Sec. 25.207(h)(2)(ii) allows a different means of providing stall
warning in icing conditions only for the relatively short time period
between when the airplane first enters icing conditions and when the
IPS is activated. (This exception to the proposed Sec. 25.207(b) is
further limited such that it only applies when the procedures for
activating the IPS do not involve waiting until a certain amount of ice
has been accumulated.)
Because there is still a safety concern with flightcrews
recognizing a stall warning that is provided by a different means than
the flightcrew would normally experience, we consider it essential that
the airplane also be shown to have safe stall characteristics. Poor
stalling characteristics with an iced wing have directly contributed to
the severity of icing accidents involving a stall in icing conditions.
As for Raytheon's comment about the cost impacts, we evaluated
these as part of the regulatory evaluation conducted for the NPRM, and
we do not agree that the cost impacts associated with this requirement
are excessive. In addition, the adopted Sec. 25.207 will not require
airplanes with stick pusher stall identification systems to have their
stick pusher activation based on a contaminated wing leading edge for
non-icing conditions. Section 25.207(h)(2)(ii) does not apply if the
same stall warning means is used for non-icing and icing conditions. If
a stick shaker is used for stall warning and if the stick shaker
activation point must be advanced due to the effect of the ice accreted
before activation of the IPS, this would result in the same negative
effect on takeoff and landing speeds. However, if the procedures for
activating the IPS ensure that it is activated before any ice accretes
on the wings, neither the stick shaker activation point nor the takeoff
and landing speeds will be affected. This could be accomplished, for
example, by using an ice detector that would activate the IPS before
ice accretes on the wings, or by procedures for activating the IPS
based on environmental conditions conducive to icing, but before ice
would actually accrete on the wings.
12. Dissipation of Ice Shapes at High Altitudes and High Mach Numbers
Proposed Sec. 25.253(c) specifies the maximum speed for
demonstrating stability characteristics in icing conditions. Proposed
Sec. 25.253(c)(3) allows this speed to be limited to the speed at
which it is demonstrated that the airframe will be free of ice
accretion due to the effects of increased dynamic pressure. Raytheon
stated that experience has shown that ice shapes dissipate quickly at
high altitude and high Mach numbers. Raytheon suggested revising Sec.
25.253(c)(3) to specify the altitude and/or Mach number range that ice
shapes would dissipate.
Although we agree that past experience shows that ice shapes
dissipate or detach at high altitude and high Mach numbers, the
applicable range may vary with airplane type. The particular conditions
under which the ice accretions dissipate or detach should be justified
as part of the certification program. Since this is consistent with
proposed Sec. 25.253(c), we made no changes to the final rule.
13. Critical Ice Shapes
Proposed appendix C, part II(a) defines how to determine the
critical ice accretions for each phase of flight. The NTSB commented
that for each phase of flight, the applicant should be required to
demonstrate that the shape, chordwise and spanwise, and the roughness
of the shapes accurately reflect the full range of appendix C
conditions in terms of mean effective drop diameter, liquid water
content, and temperature during each phase of flight. Additionally, the
NTSB suggested that we review the justification and selection of the
most critical ice shape for each phase of flight.
Although we believe the proposed requirements already address the
NTSB's concerns, we have revised appendix C, part II(a) for additional
clarity. We added text to state that applicants must demonstrate that
the full range of atmospheric icing conditions specified in part I of
appendix C have been considered, including the mean effective drop
diameter, liquid water content, and
[[Page 44662]]
temperature appropriate to the flight conditions.
14. Takeoff Ice Accretions
ALPA noted that the takeoff ice accretions defined in proposed
appendix C, part II(a)(2) do not include the entire takeoff flight
path. As defined in Sec. 25.111, the takeoff flight path ends at
either 1,500 feet above the takeoff surface, or the height at which the
transition from the takeoff to the en route configuration is completed
and the final takeoff speed (VFTO) is reached, whichever is
higher. The takeoff flight path in proposed appendix C, part II(a)(2)
ends at 1,500 feet above the takeoff surface. ALPA stated that there
are many mountainous airport locations where the takeoff configuration
must be maintained above 1,500 feet above the takeoff surface for
terrain clearance at maximum takeoff gross weights. Since winter
operations in these locations often involve icing conditions, ALPA
requested that the takeoff flight path of Appendix C, part II(a)(2) be
revised to match that of Sec. 25.111.
ALPA's comment points out an oversight in the text of the proposal.
Appendix C, part II(a)(2) has been revised to include the entire
takeoff flight path as defined in Sec. 25.111. We consider this to be
a technical clarification that does not impose a significant additional
burden on applicants.
15. Size of Ice Accretion Before Activation of the IPS
For the pre-activation ice identified in Appendix C, part II(e),
ALPA did not support the 30-second time period for the flightcrew to
see and respond to ice accreting on the airplane as stated in
paragraphs 2c(4)(a) and (b) of Appendix 1, Airframe Ice Accretion, of
proposed AC 25.21-1X. ALPA believes that the ice accreted during a more
operationally realistic timeframe and the potential degradations in
aircraft performance and handling qualities must be accounted for
during certification in order to make the proposed requirements and
acceptable means of compliance an effective combination. While a well
designed human factors study could determine an appropriate time, ALPA
proposed that at least the 2-minute time period contained in 14 CFR
33.77, Foreign object ingestion--ice, be used as the time to visually
recognize ice is accreting until definitive studies can be completed.
The FAA believes that ALPA has misunderstood the use of the 30-
second time period in the proposed AC 25.21-1X acceptable means of
compliance. The FAA does not expect the flightcrew to see and respond
to ice accumulating on the airplane within 30 seconds. In accordance
with Sec. 25.21(g), compliance must be shown using ice accretions
consistent with the AFM operating procedures. First, applicants must
determine the ice accretion that would be on the airplane when the AFM
procedures call for activating the IPS. Then, the 30-second time period
is used in combination with the continuous maximum icing environment,
as defined in appendix C of part 25, as a standard for determining the
additional ice that could accrete on the airplane before the pilot
actually activates the IPS. Since the appendix C maximum continuous
icing envelope represents at least the 99th percentile of encounters
with continuous maximum icing (that is, 99% of the time, less icing
would occur), it would take significantly longer than 30 seconds in
nearly all actual icing events for the airplane to accrete this much
ice.
As a result of this comment, the FAA reviewed the proposed AC
25.21-1X text. Although the use of a-30 second time period in a
continuous maximum icing environment is clearly stated, the FAA
believes that the text is incomplete regarding what we expect
applicants to consider in determining the ice accretion specified by
the AFM procedures for activating the IPS. The FAA is revising the
proposed AC to state that this ice accretion should be easily
recognizable by the pilot under all foreseeable conditions (for
example, at night in clouds). No changes have been made to the
regulatory requirements.
16. Maximum Size of the Critical Ice Accretion
Dassault noted that, in Europe, the critical ice accretion is
limited to a maximum thickness of 3 inches. Dassault did not find such
a limitation in the NPRM, nor in the proposed advisory circular (AC)
25.21-1X related to the NPRM. Dassault noted that this omission could
result in carrying out performance and handling tests with unrealistic
ice accretions (particularly those assumed to build up on the
unprotected parts of the airplane during the 45-minute holding flight
phase referenced in ACs 25.21-X and 25.1419-1A).
We did not make any changes to the final rule because several
existing ACs provide guidance for the size of the most critical ice
accretions that should be considered. This longstanding guidance
considers a 45-minute holding condition within an icing cloud. Since
this guidance is not regulatory, we have accepted applicants' use of
service history and other experience with other compliance criteria to
determine the maximum ice accretion that needs to be considered. We
will continue to address this issue in the same manner. The AC being
issued along with this final rule refers to these alternative methods
of compliance and provides guidance for their use.
17. Detection of Icing Conditions
A private citizen commented that icing conditions should be
monitored by more than the pilot's eyesight. We are unable to address
the commenter's issue in this rulemaking because this rulemaking only
addresses performance and handling qualities requirements for the
current methods of ice detection (which include detection by visual
means). However, we are pursuing separate rulemaking for future
airplane designs relative to allowable methods for detecting icing and
determining when to activate the IPS. In NPRM 07-07, ``Activation of
Ice Protection,'' published in the Federal Register on April 26, 2007,
we proposed to amend the airworthiness standards applicable to
transport category airplanes to require a means to ensure timely
activation of the airframe IPS.
18. Delayed Activation of the IPS
ALPA recommended modifying all rule language to eliminate
references and rule provisions for waiting until a finite amount of ice
has accumulated before activating the IPS. ALPA stated that delayed
activation of the IPS has been a factor in several accidents and
incidents. ALPA also pointed out that the FAA has adopted 17
airworthiness directives requiring immediate activation of IPS at the
first sign of ice accretion for a number of airplane types where the
previous practice was to wait until a specified amount of ice had
accumulated on the airplane. ALPA noted that after an exhaustive review
of accident and incident data, ARAC recommended an operating rule that
would remove the option of delaying activation of the IPS.
Except for the airworthiness directives referenced by ALPA, current
regulations do not prohibit AFM procedures that call for delaying
activation of the IPS until a specified amount of ice has accreted.
Although we strongly encourage activating the IPS at the first sign of
ice accretion, there may be some designs for which delayed activation
is currently acceptable, safe, and appropriate. For example, some
thermal wing IPS can currently be used in either an anti-ice or deice
mode. In the deice mode, the wing IPS is not activated until a certain
amount of ice
[[Page 44663]]
has accreted. This has not resulted in any safety issues, and can be a
more economical way of operating the wing IPS.
The purpose of this rulemaking is to provide appropriate
performance and handling qualities requirements, considering the
currently accepted procedures for activating the IPS. Establishing new
requirements for acceptable methods for activating the IPS is beyond
the scope of this rulemaking. As ALPA noted, however, ARAC has
recommended the FAA adopt new requirements that would ensure
flightcrews are provided with a clear means to know when to activate
the IPS in a timely manner. We are pursuing separate rulemaking in
response to this ARAC recommendation. In NPRM 07-07, ``Activation of
Ice Protection,'' published in the Federal Register on April 26, 2007,
we proposed to amend the airworthiness standards applicable to
transport category airplanes to require a means to ensure timely
activation of the airframe IPS. We will update the requirements adopted
by this final rule related to the means of activating the IPS, if
necessary, to be consistent with any final action resulting from NPRM
07-07, ``Activation of Ice Protection.''
19. Harmonization With EASA's NPA
Several commenters noted that the FAA did not fully harmonize the
NPRM with the EASA's NPA covering the same icing-related safety issues.
They recommended harmonizing the two rule proposals.
We worked closely with EASA to ensure that there are no significant
regulatory differences between this amendment and EASA's anticipated
final rule. However, since EASA's final rule has not yet been issued,
we cannot guarantee that the two final rules will be completely
harmonized. We believe that any differences will be primarily editorial
and not significant regulatory differences.
20. Accuracy of the Regulatory Flexibility Evaluation
GAMA requested that the FAA review the regulatory flexibility
evaluation in the interest of accuracy.
We reviewed the regulatory flexibility evaluation and reaffirmed
the determination that this proposed rule would not have a significant
economic impact on a substantial number of small entities. All U.S.
part 25 aircraft manufacturers exceed the Small Business Administration
small-entity criteria of 1,500 employees for aircraft manufacturers.
21. Aircraft Population Used When Determining Cost Versus Benefit
GAMA stated that it appeared the cost proposal considered U.S.
manufactured aircraft while the benefit section included international
products. GAMA believes that the same aircraft population should be
used when determining cost versus benefit. Additionally, GAMA stated
that it appeared it was assumed that cost was only attributed to
entirely new TC products. GAMA believes it would be appropriate to
consider the economic impact to some amount of amended TC and STC
projects as well.
Section 1 of Executive Order 12866 states ``Federal agencies should
promulgate only such regulations as are required by law, are necessary
to interpret the law, or are made necessary by compelling public need,
such as material failures of private markets to protect or improve the
health and safety of the public, the environment, or the well-being of
the American people.'' Section 5 states ``In order to reduce the
regulatory burden on the American people, their families, their
communities, their State, local, and tribal governments and their
industries * * *.'' Therefore, regulatory evaluations and flexibility
analyses focus on American people and American industries.
American industries, such as manufacturers and operators of
aircraft, must comply with regulations promulgated by Federal agencies.
Foreign firms are not required to comply with U.S. regulations unless
they choose to sell or operate their aircraft in America.
We determined the costs for this proposal by analyzing only
American manufacturing industries, since foreign firms are not required
to comply with U.S. regulations unless they choose to sell or operate
their aircraft in America. While we do consider foreign manufactured
aircraft in the benefit section, we determined the benefits by
analyzing only American operators of those aircraft. Hence, the intent
of Executive Order 12866 was satisfied.
We did include amended TCs in the analysis. Each TC includes all
derivatives for a particular aircraft model. For example, TC No. A16WE
initially covered only the Boeing 737-100, but was later amended to
include the -200 through -900 Boeing 737 models.
Future applicants for approval of changed products are subject to
Sec. 21.101 (Changed Product Rule). There are several provisions of
Sec. 21.101 allowing future applicants of changed products to comply
with earlier regulation amendments. We have already determined that
benefits of the Changed Product Rule exceed the costs. Therefore, we do
not estimate the benefits and costs of changed products for new
certification rules.
22. Value of Fatalities Avoided
A private citizen claimed that the value of the fatalities avoided
by this proposal would be in the neighborhood of $20 billion.
The number of averted fatalities and injuries is based on the
historical accident rate extrapolated into the future. The FAA used
$3.0 million for an avoided fatality and $132,700 for the additional
associated medical and legal costs' for a fatality. The derivation for
these values is discussed in the ``Economic Values for FAA Investment
and Regulatory Decisions, A Guide.'' \6\ Without the rule, we expect
that over the 45-year analysis period, approximately three accidents
will occur. These three accidents are expected to result in
approximately 12 fatalities, six serious injuries, and two minor
injuries. From these values, and expected future accidents based on
past accident history, we estimated a benefit of about $90 million over
the 45-year analysis period.
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III. Rulemaking Analyses and Notices
Paperwork Reduction Act
There are no current or new requirements for information collection
associated with this amendment.
International Compatibility
In keeping with U.S. obligations under the Convention on
International Civil Aviation, it is FAA policy to comply with
International Civil Aviation Organization (ICAO) Standards and
Recommended Practices to the maximum extent practicable. The FAA has
determined that there are no ICAO Standards and Recommended Practices
that correspond to these regulations.
Economic Assessment, Regulatory Flexibility Determination, Trade Impact
Assessment, and Unfunded Mandates Assessment
Changes to Federal regulations must undergo several economic
analyses. First, Executive Order 12866 directs each Federal agency to
propose or adopt a regulation only upon a reasoned determination that
the benefits of the intended regulation justify its costs.
[[Page 44664]]
Second, the Regulatory Flexibility Act of 1980 requires agencies to
analyze the economic impact of regulatory changes on small entities.
Third, the Trade Agreements Act (19 U.S.C. 2531-2533) prohibits
agencies from setting standards that create unnecessary obstacles to
the foreign commerce of the United States. In developing U.S.
standards, this Trade Act also requires agencies to consider
international standards and, where appropriate, use them as the basis
of U.S. standards. Fourth, the Unfunded Mandates Reform Act of 1995
(Pub. L. 104-4) requires agencies to prepare a written assessment of
the costs, benefits, and other effects of proposed or final rules that
include a Federal mandate likely to result in the expenditure by State,
local, or tribal governments, in the aggregate, or by the private
sector, of $100 million or more annually (adjusted for inflation with
the base year of 1995.)
In conducting these analyses, FAA has determined this rule (1) has
benefits that justify its costs, is not a ``significant regulatory
action'' as defined in section 3(f) of Executive Order 12866 and is not
``significant'' as defined in DOT's Regulatory Policies and Procedures;
(2) will not have a significant economic impact on a substantial number
of small entities; (3) will not reduce barriers to international trade;
and (4) does not impose an unfunded mandate on state, local, or tribal
governments, or on the private sector. These analyses, available in the
docket, are summarized below.
Introduction
This portion of the preamble summarizes the FAA's analysis of the
economic impacts of a final rule amending part 25 of Title 14, Code of
Federal Regulations (14 CFR) to change the regulations applicable to
transport category airplanes certificated for flight in icing
conditions. It also includes summaries of the regulatory flexibility
determination, the international trade impact assessment, and the
unfunded mandates assessment. We suggest readers seeking greater detail
read the full regulatory evaluation, a copy of which we have placed in
the docket for this rulemaking.
Total Benefits and Costs of This Rulemaking
The estimated potential benefits of avoiding 3 accidents over the
45-year analysis interval are $89.2 million ($23.6 million in present
value at seven percent). To obtain these benefits, over the 45-year
analysis interval, manufacturers will incur additional certification
costs of $9.8 million and the operators of these airplanes will pay
$52.5 million in additional fuel-burn. We estimate the total cost of
this final rule to be about $62.3 million and the seven percent present
value cost of the rule will be about $23.0 million.
Who Is Potentially Affected by This Rulemaking
Operators of part 25 U.S.-registered aircraft conducting
operations under FAR Parts 121, 129, and 135, and
Manufacturers of those part 25 aircraft.
Our Cost Assumptions and Sources of Information
This evaluation makes the following assumptions:
1. This final rule is assumed to become effective immediately.
2. The production runs for newly certificated part 25 airplane
models is 20 years.
3. The average life of a part 25 airplane is 25 years.
4. We analyzed the costs and benefits of this final rule over the
45-year period (20 + 25 = 45) 2006 through 2050.
5. We used a 10-year certification compliance period. For the 10-
year life-cycle period, the FAA calculated an average of four new
certifications will occur.
6. We used $3.0 million as the value of an avoided fatality.
7. New airplane certifications will occur in year one