Special Conditions: Airbus, Model A350-900 Series Airplane; Electronic Flight Control System: Lateral-Directional and Longitudinal Stability and Low Energy Awareness, 2384-2387 [2014-00449]
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Federal Register / Vol. 79, No. 9 / Tuesday, January 14, 2014 / Proposed Rules
Issued in Washington, DC, on January 8,
2014.
Kathleen B. Hogan,
Deputy Assistant Secretary for Energy
Efficiency and Renewable Energy.
[FR Doc. 2014–00515 Filed 1–13–14; 8:45 am]
BILLING CODE 6450–01–P
BUREAU OF CONSUMER FINANCIAL
PROTECTION
12 CFR Part 1006
[Docket No. CFPB–2013–0033]
RIN 3170–AA41
Debt Collection (Regulation F)
Bureau of Consumer Financial
Protection.
ACTION: Advance notice of proposed
rulemaking; extension of comment
period.
AGENCY:
On November 12, 2013, the
Bureau of Consumer Financial
Protection (the Bureau) published in the
Federal Register an Advance Notice of
Proposed Rulemaking about debt
collection practices (Debt Collection
ANPR). The Debt Collection ANPR
allowed a 90-day comment period,
closing on February 10, 2014. To allow
interested persons more time to
consider and craft their responses, the
Bureau has determined that an
extension of the comment period until
February 28, 2014 is appropriate.
DATES: The comment period for the Debt
Collection ANPR published November
12, 2013, at 78 FR 67868, is extended.
Responses must now be received on or
before February 28, 2014.
ADDRESSES: You may submit comments,
identified by Docket No. CFPB–2013–
0033 or Regulatory Identification
Number (RIN) 3170–AA41, by any of the
following methods:
• Electronic: https://
www.regulations.gov. Follow the
instructions for submitting comments.
• Mail/Hand Delivery: Monica
Jackson, Office of the Executive
Secretary, Bureau of Consumer
Financial Protection, 1700 G Street NW.,
Washington, DC 20552.
Instructions: All submissions must
include the agency name and docket
number or RIN. Please include the
question number(s) to which your
comment pertains. In general, all
comments received will be posted
without change to https://
www.regulations.gov. In addition,
comments will be available for public
inspection and copying at 1700 G Street
NW., Washington, DC 20552, on official
business days between the hours of 10
tkelley on DSK3SPTVN1PROD with PROPOSALS
SUMMARY:
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16:41 Jan 13, 2014
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a.m. and 5 p.m. Eastern Time. You can
make an appointment to inspect the
documents by calling (202) 435–7275.
All comments submitted through the
formal means described above,
including attachments and other
supporting materials, will become part
of the public record and subject to
public disclosure. Sensitive personal
information, such as account numbers
or Social Security numbers, should not
be included. Comments will not be
edited to remove any identifying or
contact information.
E-Rulemaking Initiative: The Bureau
is working with the Cornell eRulemaking Initiative (CeRI) on a pilot
project, RegulationRoom
(www.RegulationRoom.org), that uses
web technologies and approaches to
enhance public understanding and
effective participation. This ANPR on
debt collection is a focus of the project.
RegulationRoom is set up to make it
easier for consumers and others to
understand what the Bureau is
considering, to share their information,
experiences, and concerns, and to
discuss possible ideas and solutions.
Note that RegulationRoom is not an
official United States Government Web
site. Although comments made on that
site are not formal comments like those
submitted through the means identified
above, the discussion on
RegulationRoom will be captured
through a detailed summary, which
participants will have the chance to
review and suggest revisions. This
summary will be filed as a formal
comment on Regulations.gov. For
questions about this project, please
contact Whitney Patross, Counsel,
Office of Regulations, at (202) 435–7700.
FOR FURTHER INFORMATION CONTACT: For
general inquiries, submission process
questions, or any additional
information, please contact Monica
Jackson, Office of the Executive
Secretary, 202–435–7275.
SUPPLEMENTARY INFORMATION: On
November 12, 2013, the Bureau
published the Debt Collection ANPR in
the Federal Register. The Debt
Collection ANPR seeks comment, data
and information from the public about
debt collection practices.
The comment period for the Debt
Collection ANPR was to close on
February 10, 2014.
The Bureau has received three formal
written requests from industry trade
groups for an extension of the Debt
Collection ANPR comment period. The
request letters indicated more time
would enable a higher quality response
and yield greater insight to the Bureau.
The Bureau has also received informal
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inquiries from other types of
stakeholders expressing an interest in
having more time to compile
information in response to the ANPR.
The Bureau has carefully balanced
interested persons’ desire to have more
time to consider the issues raised in the
Debt Collection ANPR, gather data, and
prepare their responses, with the fact
that this is the first of what the Bureau
expects to be many opportunities for
public input over time. Accordingly, the
Bureau is extending the period allotted
for comments received pursuant to the
Debt Collection ANPR. The comment
period will now close on February 28,
2014.
Dated: January 6, 2014.
Richard Cordray,
Director, Bureau of Consumer Financial
Protection.
[FR Doc. 2014–00453 Filed 1–13–14; 8:45 am]
BILLING CODE 4810–AM–P
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA–2013–0904; Notice No.
25–13–14–SC]
Special Conditions: Airbus, Model
A350–900 Series Airplane; Electronic
Flight Control System: LateralDirectional and Longitudinal Stability
and Low Energy Awareness
Federal Aviation
Administration (FAA), DOT.
ACTION: Notice of proposed special
conditions.
AGENCY:
This action proposes special
conditions for the Airbus Model A350–
900 series airplanes. These airplanes
will have a novel or unusual design
feature(s) associated with lateraldirectional and longitudinal stability
and low energy awareness. The
applicable airworthiness regulations do
not contain adequate or appropriate
safety standards for this design feature.
These proposed special conditions
contain the additional safety standards
that the Administrator considers
necessary to establish a level of safety
equivalent to that established by the
existing airworthiness standards.
DATES: Send your comments on or
before February 28, 2014.
ADDRESSES: Send comments identified
by docket number FAA–2013–0904
using any of the following methods:
• Federal eRegulations Portal: Go to
https://www.regulations.gov/ and follow
SUMMARY:
E:\FR\FM\14JAP1.SGM
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Federal Register / Vol. 79, No. 9 / Tuesday, January 14, 2014 / Proposed Rules
the online instructions for sending your
comments electronically.
• Mail: Send comments to Docket
Operations, M–30, U.S. Department of
Transportation (DOT), 1200 New Jersey
Avenue SE., Room W12–140, West
Building Ground Floor, Washington, DC
20590–0001.
• Hand Delivery or Courier: Take
comments to Docket Operations in
Room W12–140 of the West Building
Ground Floor at 1200 New Jersey
Avenue SE., Washington, DC, between 9
a.m. and 5 p.m., Monday through
Friday, except federal holidays.
• Fax: Fax comments to Docket
Operations at 202–493–2251.
Privacy: The FAA will post all
comments it receives, without change,
to https://www.regulations.gov/,
including any personal information the
commenter provides. Using the search
function of the docket Web site, anyone
can find and read the electronic form of
all comments received into any FAA
docket, including the name of the
individual sending the comment (or
signing the comment for an association,
business, labor union, etc.). DOT’s
complete Privacy Act Statement can be
found in the Federal Register published
on April 11, 2000 (65 FR 19477–19478),
as well as at
https://DocketsInfo.dot.gov/.
Docket: Background documents or
comments received may be read at
https://www.regulations.gov/ at any time.
Follow the online instructions for
accessing the docket or go to the Docket
Operations in Room W12–140 of the
West Building Ground Floor at 1200
New Jersey Avenue SE., Washington,
DC, between 9 a.m. and 5 p.m., Monday
through Friday, except federal holidays.
FOR FURTHER INFORMATION CONTACT: Joe
Jacobsen, FAA, Airplane and Flightcrew
Interface Branch, ANM–111, Transport
Airplane Directorate, Aircraft
Certification Service, 1601 Lind Avenue
SW., Renton, Washington 98057–3356;
telephone (425) 227–2011; facsimile
(425) 227–1320.
SUPPLEMENTARY INFORMATION:
tkelley on DSK3SPTVN1PROD with PROPOSALS
Comments Invited
We invite interested people to take
part in this rulemaking by sending
written comments, data, or views. The
most helpful comments reference a
specific portion of the special
conditions, explain the reason for any
recommended change, and include
supporting data.
We will consider all comments we
receive on or before the closing date for
comments. We may change these
proposed special conditions based on
the comments we receive.
VerDate Mar<15>2010
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Background
On August 25, 2008, Airbus applied
for a type certificate for their new Model
A350–900 series airplane. Later, Airbus
requested and the FAA approved an
extension to the application for FAA
type certification to June 28, 2009. The
Model A350–900 series has a
conventional layout with twin wingmounted Rolls-Royce Trent XWB
engines. It features a twin aisle 9-abreast
economy class layout, and
accommodates side-by-side placement
of LD–3 containers in the cargo
compartment. The basic Model A350–
900 series configuration will
accommodate 315 passengers in a
standard two-class arrangement. The
design cruise speed is Mach 0.85 with
a Maximum Take-Off Weight of 602,000
lbs. Airbus proposes the Model A350–
900 series to be certified for extended
operations (ETOPS) beyond 180 minutes
at entry into service for up to a 420minute maximum diversion time.
Lateral-Directional Static Stability
The electronic flight control system
(EFCS) on the A350, like its
predecessors the A320, A330, A340, and
A380, contains fly-by-wire control laws
that can result in neutral lateraldirectional static stability; therefore, the
conventional requirements in the
regulations are not met.
Positive static directional stability is
defined as the tendency to recover from
a skid with the rudder free. Positive
static lateral stability is defined as the
tendency to raise the low wing in a
sideslip with the aileron controls free.
These control criteria are intended to
accomplish the following:
(a) Provide additional cues of
inadvertent sideslips and skids through
control force changes.
(b) Ensure that short periods of
unattended operation do not result in
any significant changes in yaw or bank
angle.
(c) Provide predictable roll and yaw
response.
(d) Provide acceptable level of pilot
attention (workload) to attain and
maintain a coordinated turn.
The Flight Test Harmonization
Working Group has recommended a rule
and advisory material change for
§ 25.177, Static lateral-directional
stability. This harmonized text will form
the basis for these proposed special
conditions.
Longitudinal Static Stability
Static longitudinal stability on
airplanes with mechanical links to the
pitch control surface means that a pull
force on the controller will result in a
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reduction in speed relative to the trim
speed, and a push force will result in a
higher speed than the trim speed.
Longitudinal stability is required by the
regulations for the following reasons:
(a) Speed change cues are provided to
the pilot through increased and
decreased forces on the controller.
(b) Short periods of unattended
control of the airplane do not result in
significant changes in attitude, airspeed
or load factor.
(c) A predictable pitch response is
provided to the pilot.
(d) An acceptable level of pilot
attention (workload) to attain and
maintain trim speed and altitude is
provided to the pilot.
(e) Longitudinal stability provides
gust stability.
The pitch control movement of the
sidestick on the A350 is designed to be
a normal load factor or ‘‘g’’ command
that results in an initial movement of
the elevator surface to attain the
commanded load factor that’s then
followed by integrated movement of the
stabilizer and elevator to automatically
trim the airplane to a neutral, 1g, stickfree stability. The flight path
commanded by the initial sidestick
input will remain, stick-free, until
another command is given by the pilot.
This control function is applied during
‘‘normal’’ control law within the speed
range from initiation of the angle of
attack protection limit, Vαprot, to VMO/
MMO. Once outside this speed range, the
control laws introduce the conventional
longitudinal static stability as described
above.
As a result of neutral static stability,
the A350 does not meet the
requirements in 14 CFR part 25 for static
longitudinal stability.
Low Energy Awareness
Past experience on airplanes fitted
with a flight control system providing
neutral longitudinal stability shows
there is insufficient feedback cues to the
pilot of excursion below normal
operational speeds. The maximum angle
of attack protection system limits the
airplane angle of attack and prevents
stall during normal operating speeds,
but this system is not sufficient to
prevent stall at low speed excursions
below normal operational speeds. Until
intervention, there are no stability cues
since the aircraft remains trimmed.
Additionally, feedback from the
pitching moment due to thrust variation
is reduced by the flight control laws.
Recovery from a low speed excursion
may become hazardous when the low
speed situation is associated with a low
altitude and with the engines at low
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Federal Register / Vol. 79, No. 9 / Tuesday, January 14, 2014 / Proposed Rules
thrust or with performance limiting
conditions.
Type Certification Basis
Under Title 14, Code of Federal
Regulations (14 CFR) 21.17, Airbus must
show that the Model A350–900 series
meets the applicable provisions of 14
CFR part 25, as amended by
Amendments 25–1 through 25–129.
If the Administrator finds that the
applicable airworthiness regulations
(i.e., 14 CFR part 25) do not contain
adequate or appropriate safety standards
for the Model A350–900 series because
of a novel or unusual design feature,
special conditions are prescribed under
§ 21.16.
Special conditions are initially
applicable to the model for which they
are issued. Should the type certificate
for that model be amended later to
include any other model that
incorporates the same or similar novel
or unusual design feature, the proposed
special conditions would also apply to
the other model under § 21.101.
In addition to the applicable
airworthiness regulations and proposed
special conditions, the Model A350–900
series must comply with the fuel vent
and exhaust emission requirements of
14 CFR part 34 and the noise
certification requirements of 14 CFR
part 36 and the FAA must issue a
finding of regulatory adequacy under
§ 611 of Public Law 92–574, the ‘‘Noise
Control Act of 1972.’’
The FAA issues special conditions, as
defined in 14 CFR 11.19, under § 11.38,
and they become part of the typecertification basis under § 21.17(a)(2).
tkelley on DSK3SPTVN1PROD with PROPOSALS
Novel or Unusual Design Features
The Airbus Model A350–900 series
will incorporate the following novel or
unusual design features: A flight control
design feature within the normal
operational envelope in which side stick
deflection in the roll axis commands
roll rate; an operational design which
does not comply with the static
longitudinal stability requirements of
§§ 25.171, 25.173, and 25.175, and a low
energy state where recovery may
become hazardous when associated
with a low altitude and performance
limiting conditions.
Discussion
1. In the absence of positive lateral
stability, the curve of lateral control
surface deflections against sideslip
angle should be in a conventional sense,
and reasonably in harmony with rudder
deflection during steady heading
sideslip maneuvers.
2. Since conventional relationships
between stick forces and control surface
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displacements do not apply to the ‘‘load
factor command’’ flight control system
on the A350, longitudinal stability
characteristics should be evaluated by
assessing the airplane handling qualities
during simulator and flight test
maneuvers appropriate to operation of
the airplane. This may be accomplished
by using the Handling Qualities Rating
Method presented in Appendix 7 of the
Flight Test Guide, AC 25–7A, or an
acceptable alternative method proposed
by Airbus. Important considerations are
as follows:
(a) Adequate speed control without
excessive pilot workload
(b) Acceptable high and low speed
protection, and
(c) Provision for adequate cues to the
pilot of significant speed excursions
beyond VMO/MMO, and low speed
awareness flight conditions.
3. The airplane should provide
adequate awareness cues to the pilot of
a low energy (low speed/low thrust/low
height) state to ensure that the airplane
retains sufficient energy to recover
when flight control laws provide neutral
longitudinal stability significantly
below the normal operating speeds. This
may be accomplished as follows:
(a) Adequate low speed/low thrust
cues at low altitude may be provided by
a strong positive static stability force
gradient (1 pound per 6 knots applied
through the sidestick), or
(b) The low energy awareness may be
provided by an appropriate warning
with the following characteristics:
(i) It should be unique, unambiguous,
and unmistakable.
(ii) It should be active at appropriate
altitudes and in appropriate
configurations (i.e., at low altitude, in
the approach and landing
configurations).
(iii) It should be sufficiently timely to
allow recovery to a stabilized flight
condition inside the normal flight
envelope while maintaining the desired
flight path and without entering the
flight controls angle-of-attack protection
mode.
(iv) It should not be triggered during
normal operation, including operation
in moderate turbulence for
recommended maneuvers at
recommended speeds.
(v) It should not be cancelable by the
pilot other than by achieving a higher
energy state.
(vi) There should be an adequate
hierarchy among the various warnings
so that the pilot is not confused and led
to take inappropriate recovery action if
multiple warnings occur.
(c) Global energy awareness and nonnuisance of low energy cues should be
evaluated by simulator and flight tests
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in the whole take-off and landing
altitude range for which certification is
requested. This would include all
relevant combinations of weight, center
of gravity position, configuration,
airbrakes position, and available thrust,
including reduced and derated take-off
thrust operations and engine failure
cases. A sufficient number of tests
should be conducted, allowing the level
of energy awareness and the effects of
energy management errors to be
assessed.
Applicability
As discussed above, these proposed
special conditions apply to Airbus
Model A350–900 series airplanes.
Should Airbus apply later for a change
to the type certificate to include another
model incorporating the same novel or
unusual design feature, the proposed
special conditions would apply to that
model as well.
Conclusion
This action affects only certain novel
or unusual design features on the Airbus
Model A350–900 series airplanes. It is
not a rule of general applicability.
List of Subjects in 14 CFR part 25
Aircraft, Aviation safety, Reporting
and recordkeeping requirements.
The authority citation for these
special conditions is as follows:
■
Authority: 49 U.S.C. 106(g), 40113, 44701,
44702, 44704.
The Proposed Special Conditions
Accordingly, the Federal Aviation
Administration (FAA) proposes the
following special conditions as part of
the type certification basis for Airbus
Model A350–900 series airplanes.
1. Electronic Flight Control System:
Lateral-Directional and Longitudinal
Stability and Low Energy Awareness. In
lieu of the requirements of §§ 25.171,
25.173, 25.175 and 25.177, the following
special conditions apply:
a. The airplane must be shown to
have suitable static lateral, directional,
and longitudinal stability in any
condition normally encountered in
service, including the effects of
atmospheric disturbance. The showing
of suitable static lateral, directional, and
longitudinal stability must be based on
the airplane handling qualities,
including pilot workload and pilot
compensation, for specific test
procedures during the flight test
evaluations.
b. The airplane must provide
adequate awareness to the pilot of a low
energy (low speed/low thrust/low
height) state when fitted with flight
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Federal Register / Vol. 79, No. 9 / Tuesday, January 14, 2014 / Proposed Rules
control laws presenting neutral
longitudinal stability significantly
below the normal operating speeds.
‘‘Adequate awareness’’ means warning
information must be provided to alert
the crew of unsafe operating conditions
and to enable them to take appropriate
corrective action.
c. The static directional stability (as
shown by the tendency to recover from
a skid with the rudder free) must be
positive for any landing gear and flap
position and symmetrical power
condition, at speeds from 1.13 VSR1, up
to VFE, VLE, or VFC/MFC (as appropriate).
d. The static lateral stability (as
shown by the tendency to raise the low
wing in a sideslip with the aileron
controls free) for any landing gear and
wing-flap position and symmetric
power condition, may not be negative at
any airspeed (except that speeds higher
than VFE need not be considered for
wing-flaps extended configurations nor
speeds higher than VLE for landing gear
extended configurations) in the
following airspeed ranges:
(1) From 1.13 VSR1 to VMO /MMO.
(2) From VMO/MMO to VFC/MFC, unless
the divergence is—
(i) Gradual;
(ii) Easily recognizable by the pilot;
and
(iii) Easily controllable by the pilot.
e. In straight, steady sideslips over the
range of sideslip angles appropriate to
the operation of the airplane, but not
less than those obtained with one-half of
the available rudder control movement
(but not exceeding a rudder control
force of 180 pounds), rudder control
movements and forces must be
substantially proportional to the angle
of sideslip in a stable sense; and the
factor of proportionality must lie
between limits found necessary for safe
operation. This requirement must be
met for the configurations and speeds
specified in paragraph (c) of this
section.
f. For sideslip angles greater than
those prescribed by paragraph (e) of this
section, up to the angle at which full
rudder control is used or a rudder
control force of 180 pounds is obtained,
the rudder control forces may not
reverse, and increased rudder deflection
must be needed for increased angles of
sideslip. Compliance with this
requirement must be shown using
straight, steady sideslips, unless full
lateral control input is achieved before
reaching either full rudder control input
or a rudder control force of 180 pounds;
a straight, steady sideslip need not be
maintained after achieving full lateral
control input. This requirement must be
met at all approved landing gear and
wing-flap positions for the range of
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operating speeds and power conditions
appropriate to each landing gear and
wing-flap position with all engines
operating.
Issued in Renton, Washington, on October
22, 2013.
Stephen P. Boyd,
Acting Manager, Transport Airplane
Directorate, Aircraft Certification Service.
[FR Doc. 2014–00449 Filed 1–13–14; 8:45 am]
BILLING CODE 4910–13–P
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA–2013–0900; Notice No. 25–
12–08–SC]
Special Conditions: Airbus, Model
A350–900 Series Airplane; General
Limiting Requirements
Federal Aviation
Administration (FAA), DOT.
ACTION: Notice of proposed special
conditions.
AGENCY:
This action proposes special
conditions for the Airbus Model A350–
900 series airplanes. This airplane will
have a novel or unusual design feature
associated with general limiting
requirements of its flight envelope
protection features. The applicable
airworthiness regulations do not contain
adequate or appropriate safety standards
for this design feature. These proposed
special conditions contain the
additional safety standards that the
Administrator considers necessary to
establish a level of safety equivalent to
that established by the existing
airworthiness standards.
DATES: Send your comments on or
before February 28, 2014.
ADDRESSES: Send comments identified
by docket number FAA–2013–0900
using any of the following methods:
• Federal eRegulations Portal: Go to
https://www.regulations.gov/ and follow
the online instructions for sending your
comments electronically.
• Mail: Send comments to Docket
Operations, M–30, U.S. Department of
Transportation (DOT), 1200 New Jersey
Avenue SE., Room W12–140, West
Building Ground Floor, Washington, DC
20590–0001.
• Hand Delivery or Courier: Take
comments to Docket Operations in
Room W12–140 of the West Building
Ground Floor at 1200 New Jersey
Avenue SE., Washington, DC, between 9
a.m. and 5 p.m., Monday through
Friday, except federal holidays.
SUMMARY:
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2387
• Fax: Fax comments to Docket
Operations at 202–493–2251.
Privacy: The FAA will post all
comments it receives, without change,
to https://www.regulations.gov/,
including any personal information the
commenter provides. Using the search
function of the docket Web site, anyone
can find and read the electronic form of
all comments received into any FAA
docket, including the name of the
individual sending the comment (or
signing the comment for an association,
business, labor union, etc.). DOT’s
complete Privacy Act Statement can be
found in the Federal Register published
on April 11, 2000 (65 FR 19477–19478),
as well as at
https://DocketsInfo.dot.gov/.
Docket: Background documents or
comments received may be read at
https://www.regulations.gov/ at any time.
Follow the online instructions for
accessing the docket or go to the Docket
Operations in Room W12–140 of the
West Building Ground Floor at 1200
New Jersey Avenue SE., Washington,
DC, between 9 a.m. and 5 p.m., Monday
through Friday, except federal holidays.
FOR FURTHER INFORMATION CONTACT: Joe
Jacobsen, FAA, Airplane and Flightcrew
Interface, ANM–111, Transport Airplane
Directorate, Aircraft Certification
Service, 1601 Lind Avenue SW.,
Renton, Washington, 98057–3356;
telephone (425) 227–2011; facsimile
(425) 227–1320.
SUPPLEMENTARY INFORMATION:
Comments Invited
We invite interested people to take
part in this rulemaking by sending
written comments, data, or views. The
most helpful comments reference a
specific portion of the special
conditions, explain the reason for any
recommended change, and include
supporting data. We ask that you send
us two copies of written comments.
We will consider all comments we
receive on or before the closing date for
comments. We may change these special
conditions based on the comments we
receive.
Background
On August 25, 2008, Airbus applied
for a type certificate for their new Model
A350–900 series airplane. Later, Airbus
requested and the FAA approved an
extension to the application for FAA
type certification to June 28, 2009. The
Model A350–900 series has a
conventional layout with twin wingmounted Rolls-Royce Trent engines. It
features a twin aisle 9-abreast economy
class layout, and accommodates side-byside placement of LD–3 containers in
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]]>Agencies
[Federal Register Volume 79, Number 9 (Tuesday, January 14, 2014)]
[Proposed Rules]
[Pages 2384-2387]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2014-00449]
=======================================================================
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA-2013-0904; Notice No. 25-13-14-SC]
Special Conditions: Airbus, Model A350-900 Series Airplane;
Electronic Flight Control System: Lateral-Directional and Longitudinal
Stability and Low Energy Awareness
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed special conditions.
-----------------------------------------------------------------------
SUMMARY: This action proposes special conditions for the Airbus Model
A350-900 series airplanes. These airplanes will have a novel or unusual
design feature(s) associated with lateral-directional and longitudinal
stability and low energy awareness. The applicable airworthiness
regulations do not contain adequate or appropriate safety standards for
this design feature. These proposed special conditions contain the
additional safety standards that the Administrator considers necessary
to establish a level of safety equivalent to that established by the
existing airworthiness standards.
DATES: Send your comments on or before February 28, 2014.
ADDRESSES: Send comments identified by docket number FAA-2013-0904
using any of the following methods:
Federal eRegulations Portal: Go to https://www.regulations.gov/ and follow
[[Page 2385]]
the online instructions for sending your comments electronically.
Mail: Send comments to Docket Operations, M-30, U.S.
Department of Transportation (DOT), 1200 New Jersey Avenue SE., Room
W12-140, West Building Ground Floor, Washington, DC 20590-0001.
Hand Delivery or Courier: Take comments to Docket
Operations in Room W12-140 of the West Building Ground Floor at 1200
New Jersey Avenue SE., Washington, DC, between 9 a.m. and 5 p.m.,
Monday through Friday, except federal holidays.
Fax: Fax comments to Docket Operations at 202-493-2251.
Privacy: The FAA will post all comments it receives, without
change, to https://www.regulations.gov/, including any personal
information the commenter provides. Using the search function of the
docket Web site, anyone can find and read the electronic form of all
comments received into any FAA docket, including the name of the
individual sending the comment (or signing the comment for an
association, business, labor union, etc.). DOT's complete Privacy Act
Statement can be found in the Federal Register published on April 11,
2000 (65 FR 19477-19478), as well as at https://DocketsInfo.dot.gov/.
Docket: Background documents or comments received may be read at
https://www.regulations.gov/ at any time. Follow the online instructions
for accessing the docket or go to the Docket Operations in Room W12-140
of the West Building Ground Floor at 1200 New Jersey Avenue SE.,
Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday,
except federal holidays.
FOR FURTHER INFORMATION CONTACT: Joe Jacobsen, FAA, Airplane and
Flightcrew Interface Branch, ANM-111, Transport Airplane Directorate,
Aircraft Certification Service, 1601 Lind Avenue SW., Renton,
Washington 98057-3356; telephone (425) 227-2011; facsimile (425) 227-
1320.
SUPPLEMENTARY INFORMATION:
Comments Invited
We invite interested people to take part in this rulemaking by
sending written comments, data, or views. The most helpful comments
reference a specific portion of the special conditions, explain the
reason for any recommended change, and include supporting data.
We will consider all comments we receive on or before the closing
date for comments. We may change these proposed special conditions
based on the comments we receive.
Background
On August 25, 2008, Airbus applied for a type certificate for their
new Model A350-900 series airplane. Later, Airbus requested and the FAA
approved an extension to the application for FAA type certification to
June 28, 2009. The Model A350-900 series has a conventional layout with
twin wing-mounted Rolls-Royce Trent XWB engines. It features a twin
aisle 9-abreast economy class layout, and accommodates side-by-side
placement of LD-3 containers in the cargo compartment. The basic Model
A350-900 series configuration will accommodate 315 passengers in a
standard two-class arrangement. The design cruise speed is Mach 0.85
with a Maximum Take-Off Weight of 602,000 lbs. Airbus proposes the
Model A350-900 series to be certified for extended operations (ETOPS)
beyond 180 minutes at entry into service for up to a 420-minute maximum
diversion time.
Lateral-Directional Static Stability
The electronic flight control system (EFCS) on the A350, like its
predecessors the A320, A330, A340, and A380, contains fly-by-wire
control laws that can result in neutral lateral-directional static
stability; therefore, the conventional requirements in the regulations
are not met.
Positive static directional stability is defined as the tendency to
recover from a skid with the rudder free. Positive static lateral
stability is defined as the tendency to raise the low wing in a
sideslip with the aileron controls free. These control criteria are
intended to accomplish the following:
(a) Provide additional cues of inadvertent sideslips and skids
through control force changes.
(b) Ensure that short periods of unattended operation do not result
in any significant changes in yaw or bank angle.
(c) Provide predictable roll and yaw response.
(d) Provide acceptable level of pilot attention (workload) to
attain and maintain a coordinated turn.
The Flight Test Harmonization Working Group has recommended a rule
and advisory material change for Sec. 25.177, Static lateral-
directional stability. This harmonized text will form the basis for
these proposed special conditions.
Longitudinal Static Stability
Static longitudinal stability on airplanes with mechanical links to
the pitch control surface means that a pull force on the controller
will result in a reduction in speed relative to the trim speed, and a
push force will result in a higher speed than the trim speed.
Longitudinal stability is required by the regulations for the following
reasons:
(a) Speed change cues are provided to the pilot through increased
and decreased forces on the controller.
(b) Short periods of unattended control of the airplane do not
result in significant changes in attitude, airspeed or load factor.
(c) A predictable pitch response is provided to the pilot.
(d) An acceptable level of pilot attention (workload) to attain and
maintain trim speed and altitude is provided to the pilot.
(e) Longitudinal stability provides gust stability.
The pitch control movement of the sidestick on the A350 is designed
to be a normal load factor or ``g'' command that results in an initial
movement of the elevator surface to attain the commanded load factor
that's then followed by integrated movement of the stabilizer and
elevator to automatically trim the airplane to a neutral, 1g, stick-
free stability. The flight path commanded by the initial sidestick
input will remain, stick-free, until another command is given by the
pilot. This control function is applied during ``normal'' control law
within the speed range from initiation of the angle of attack
protection limit, Vaprot, to VMO/MMO.
Once outside this speed range, the control laws introduce the
conventional longitudinal static stability as described above.
As a result of neutral static stability, the A350 does not meet the
requirements in 14 CFR part 25 for static longitudinal stability.
Low Energy Awareness
Past experience on airplanes fitted with a flight control system
providing neutral longitudinal stability shows there is insufficient
feedback cues to the pilot of excursion below normal operational
speeds. The maximum angle of attack protection system limits the
airplane angle of attack and prevents stall during normal operating
speeds, but this system is not sufficient to prevent stall at low speed
excursions below normal operational speeds. Until intervention, there
are no stability cues since the aircraft remains trimmed. Additionally,
feedback from the pitching moment due to thrust variation is reduced by
the flight control laws. Recovery from a low speed excursion may become
hazardous when the low speed situation is associated with a low
altitude and with the engines at low
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thrust or with performance limiting conditions.
Type Certification Basis
Under Title 14, Code of Federal Regulations (14 CFR) 21.17, Airbus
must show that the Model A350-900 series meets the applicable
provisions of 14 CFR part 25, as amended by Amendments 25-1 through 25-
129.
If the Administrator finds that the applicable airworthiness
regulations (i.e., 14 CFR part 25) do not contain adequate or
appropriate safety standards for the Model A350-900 series because of a
novel or unusual design feature, special conditions are prescribed
under Sec. 21.16.
Special conditions are initially applicable to the model for which
they are issued. Should the type certificate for that model be amended
later to include any other model that incorporates the same or similar
novel or unusual design feature, the proposed special conditions would
also apply to the other model under Sec. 21.101.
In addition to the applicable airworthiness regulations and
proposed special conditions, the Model A350-900 series must comply with
the fuel vent and exhaust emission requirements of 14 CFR part 34 and
the noise certification requirements of 14 CFR part 36 and the FAA must
issue a finding of regulatory adequacy under Sec. 611 of Public Law
92-574, the ``Noise Control Act of 1972.''
The FAA issues special conditions, as defined in 14 CFR 11.19,
under Sec. 11.38, and they become part of the type-certification basis
under Sec. 21.17(a)(2).
Novel or Unusual Design Features
The Airbus Model A350-900 series will incorporate the following
novel or unusual design features: A flight control design feature
within the normal operational envelope in which side stick deflection
in the roll axis commands roll rate; an operational design which does
not comply with the static longitudinal stability requirements of
Sec. Sec. 25.171, 25.173, and 25.175, and a low energy state where
recovery may become hazardous when associated with a low altitude and
performance limiting conditions.
Discussion
1. In the absence of positive lateral stability, the curve of
lateral control surface deflections against sideslip angle should be in
a conventional sense, and reasonably in harmony with rudder deflection
during steady heading sideslip maneuvers.
2. Since conventional relationships between stick forces and
control surface displacements do not apply to the ``load factor
command'' flight control system on the A350, longitudinal stability
characteristics should be evaluated by assessing the airplane handling
qualities during simulator and flight test maneuvers appropriate to
operation of the airplane. This may be accomplished by using the
Handling Qualities Rating Method presented in Appendix 7 of the Flight
Test Guide, AC 25-7A, or an acceptable alternative method proposed by
Airbus. Important considerations are as follows:
(a) Adequate speed control without excessive pilot workload
(b) Acceptable high and low speed protection, and
(c) Provision for adequate cues to the pilot of significant speed
excursions beyond VMO/MMO, and low speed
awareness flight conditions.
3. The airplane should provide adequate awareness cues to the pilot
of a low energy (low speed/low thrust/low height) state to ensure that
the airplane retains sufficient energy to recover when flight control
laws provide neutral longitudinal stability significantly below the
normal operating speeds. This may be accomplished as follows:
(a) Adequate low speed/low thrust cues at low altitude may be
provided by a strong positive static stability force gradient (1 pound
per 6 knots applied through the sidestick), or
(b) The low energy awareness may be provided by an appropriate
warning with the following characteristics:
(i) It should be unique, unambiguous, and unmistakable.
(ii) It should be active at appropriate altitudes and in
appropriate configurations (i.e., at low altitude, in the approach and
landing configurations).
(iii) It should be sufficiently timely to allow recovery to a
stabilized flight condition inside the normal flight envelope while
maintaining the desired flight path and without entering the flight
controls angle-of-attack protection mode.
(iv) It should not be triggered during normal operation, including
operation in moderate turbulence for recommended maneuvers at
recommended speeds.
(v) It should not be cancelable by the pilot other than by
achieving a higher energy state.
(vi) There should be an adequate hierarchy among the various
warnings so that the pilot is not confused and led to take
inappropriate recovery action if multiple warnings occur.
(c) Global energy awareness and non-nuisance of low energy cues
should be evaluated by simulator and flight tests in the whole take-off
and landing altitude range for which certification is requested. This
would include all relevant combinations of weight, center of gravity
position, configuration, airbrakes position, and available thrust,
including reduced and derated take-off thrust operations and engine
failure cases. A sufficient number of tests should be conducted,
allowing the level of energy awareness and the effects of energy
management errors to be assessed.
Applicability
As discussed above, these proposed special conditions apply to
Airbus Model A350-900 series airplanes. Should Airbus apply later for a
change to the type certificate to include another model incorporating
the same novel or unusual design feature, the proposed special
conditions would apply to that model as well.
Conclusion
This action affects only certain novel or unusual design features
on the Airbus Model A350-900 series airplanes. It is not a rule of
general applicability.
List of Subjects in 14 CFR part 25
Aircraft, Aviation safety, Reporting and recordkeeping
requirements.
0
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.
The Proposed Special Conditions
Accordingly, the Federal Aviation Administration (FAA) proposes the
following special conditions as part of the type certification basis
for Airbus Model A350-900 series airplanes.
1. Electronic Flight Control System: Lateral-Directional and
Longitudinal Stability and Low Energy Awareness. In lieu of the
requirements of Sec. Sec. 25.171, 25.173, 25.175 and 25.177, the
following special conditions apply:
a. The airplane must be shown to have suitable static lateral,
directional, and longitudinal stability in any condition normally
encountered in service, including the effects of atmospheric
disturbance. The showing of suitable static lateral, directional, and
longitudinal stability must be based on the airplane handling
qualities, including pilot workload and pilot compensation, for
specific test procedures during the flight test evaluations.
b. The airplane must provide adequate awareness to the pilot of a
low energy (low speed/low thrust/low height) state when fitted with
flight
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control laws presenting neutral longitudinal stability significantly
below the normal operating speeds. ``Adequate awareness'' means warning
information must be provided to alert the crew of unsafe operating
conditions and to enable them to take appropriate corrective action.
c. The static directional stability (as shown by the tendency to
recover from a skid with the rudder free) must be positive for any
landing gear and flap position and symmetrical power condition, at
speeds from 1.13 VSR1, up to VFE, VLE,
or VFC/MFC (as appropriate).
d. The static lateral stability (as shown by the tendency to raise
the low wing in a sideslip with the aileron controls free) for any
landing gear and wing-flap position and symmetric power condition, may
not be negative at any airspeed (except that speeds higher than
VFE need not be considered for wing-flaps extended
configurations nor speeds higher than VLE for landing gear
extended configurations) in the following airspeed ranges:
(1) From 1.13 VSR1 to VMO /
MMO.
(2) From VMO/MMO to VFC/
MFC, unless the divergence is--
(i) Gradual;
(ii) Easily recognizable by the pilot; and
(iii) Easily controllable by the pilot.
e. In straight, steady sideslips over the range of sideslip angles
appropriate to the operation of the airplane, but not less than those
obtained with one-half of the available rudder control movement (but
not exceeding a rudder control force of 180 pounds), rudder control
movements and forces must be substantially proportional to the angle of
sideslip in a stable sense; and the factor of proportionality must lie
between limits found necessary for safe operation. This requirement
must be met for the configurations and speeds specified in paragraph
(c) of this section.
f. For sideslip angles greater than those prescribed by paragraph
(e) of this section, up to the angle at which full rudder control is
used or a rudder control force of 180 pounds is obtained, the rudder
control forces may not reverse, and increased rudder deflection must be
needed for increased angles of sideslip. Compliance with this
requirement must be shown using straight, steady sideslips, unless full
lateral control input is achieved before reaching either full rudder
control input or a rudder control force of 180 pounds; a straight,
steady sideslip need not be maintained after achieving full lateral
control input. This requirement must be met at all approved landing
gear and wing-flap positions for the range of operating speeds and
power conditions appropriate to each landing gear and wing-flap
position with all engines operating.
Issued in Renton, Washington, on October 22, 2013.
Stephen P. Boyd,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 2014-00449 Filed 1-13-14; 8:45 am]
BILLING CODE 4910-13-P
