Special Conditions: Dassault Aviation Model Falcon 7X Airplane; Sudden Engine Stoppage, Operation Without Normal Electrical Power, and Dive Speed Definition With Speed Protection System, 18372-18375 [E7-6889]
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Federal Register / Vol. 72, No. 70 / Thursday, April 12, 2007 / Rules and Regulations
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period of time appropriate to the
maneuvers.
(4) It must always be possible to
reduce incidence by conventional use of
the controller.
(5) The rate at which the airplane can
be maneuvered from trim speeds
associated with scheduled operating
speeds, such as V2 and VREF, up to
alpha-limit must not be unduly damped
or significantly slower than can be
achieved on conventionally controlled
transport airplanes.
g. Atmospheric Disturbances.
Operation of the high incidence
protection function must not adversely
affect aircraft control during expected
levels of atmospheric disturbances or
impede the application of recovery
procedures in case of windshear.
Simulator tests and analysis may be
used to evaluate such conditions but
must be validated by limited flight
testing to confirm handling qualities at
critical loading conditions.
h. [Reserved]
i. Proof of Compliance. In addition to
the requirements of § 25.21, the
following special conditions apply:
The flying qualities must be evaluated
at the most unfavorable center of gravity
position.
j. Longitudinal Control:
(1) In lieu of the requirements of
§ 25.145(a) and (a)(1), the following
special conditions apply:
It must be possible—at any point
between the trim speed for straight
flight and Vmin—to pitch the nose
downward, so that the acceleration to
this selected trim speed is prompt, with:
The airplane trimmed for straight
flight at the speed achievable by the
automatic trim system and at the most
unfavorable center of gravity;
(2) In lieu of the requirements of
§ 25.145(b)(6), the following special
conditions apply:
With power off, flaps extended and
the airplane trimmed at 1.3 VSR1, obtain
and maintain airspeeds between Vmin
and either 1.6 VSR1 or VFE, whichever is
lower.
k. Airspeed Indicating System. (1) In
lieu of the requirements of
§ 25.1323(c)(1), the following special
conditions apply: VMO to Vmin with the
flaps retracted.
(2) In lieu of the requirements of
§ 25.1323(c)(2), the following special
conditions apply: Vmin to VFE with flaps
in the landing position.
7. Flight Envelope Protection: Normal
Load Factor (g) Limiting
In addition to the requirements of
§ 25.143(a)—and in the absence of other
limiting factors—the following special
conditions apply:
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a. The positive limiting load factor
must not be less than:
(1) 2.5g for the Electronic Flight
Control System (EFCS) normal state.
(2) 2.0g for the EFCS normal state
with the high lift devices extended.
b. The negative limiting load factor
must be equal to or more negative than:
(1) Minus 1.0g for the EFCS normal
state.
(2) 0.0g for the EFCS normal state
with high lift devices extended.
Note: This special condition does not
impose an upper bound for the normal load
factor limit, nor does it require that the limit
exist. If the limit is set at a value beyond the
structural design limit maneuvering load
factor ‘‘n,’’ indicated in §§ 25.333(b) and
25.337(b) and (c), there should be a very
positive tactile feel built into the controller
and obvious to the pilot that serves as a
deterrent to inadvertently exceeding the
structural limit.
8. Flight Envelope Protection: Pitch,
Roll, and High Speed Limiting
Functions
In addition to § 25.143, the following
special conditions apply:
a. Operation of the high speed limiter
during all routine and descent
procedure flight must not impede
normal attainment of speeds up to the
overspeed warning.
b. The pitch limiting function must
not impede airplane maneuvering,
including an all-engines operating
takeoff, for pitch angles up to the
maximum required for normal
operations plus a suitable margin in the
pitch axis to allow for satisfactory speed
control.
c. The high speed limiting function
must not impede normal attainment of
speeds up to VMO/MMO during all
routine and descent procedure flight
conditions.
d. The pitch and roll limiting
functions must not restrict nor prevent
attaining bank angles up to 65 degrees
and pitch attitudes necessary for
emergency maneuvering. Positive spiral
stability, which is introduced above 35
degrees bank angle, must not require
excessive pilot strength on the side stick
controller to achieve bank angles up to
65 degrees. Stick force at bank angles
greater than 35 degrees must not be so
light that over-control would lead to
pilot-induced oscillations.
Issued in Renton, Washington, on April 4,
2007.
Stephen P. Boyd,
Acting Manager, Transport Airplane
Directorate, Aircraft Certification Service.
[FR Doc. E7–6888 Filed 4–11–07; 8:45 am]
BILLING CODE 4910–13–P
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM371; Special Conditions No.
25–350–SC]
Special Conditions: Dassault Aviation
Model Falcon 7X Airplane; Sudden
Engine Stoppage, Operation Without
Normal Electrical Power, and Dive
Speed Definition With Speed
Protection System
Federal Aviation
Administration (FAA), DOT.
ACTION: Final special conditions.
AGENCY:
SUMMARY: These special conditions are
issued for the Dassault Aviation Model
Falcon 7X Airplane; Sudden Engine
Stoppage, Operation Without Normal
Electrical Power, and Dive Speed
Definition with Speed Protection
System. This airplane will have novel or
unusual design features that include
engine size and torque load, which
affect sudden engine stoppage; electrical
and electronic systems which perform
critical functions, which affect
operation without normal electrical
power; and dive speed definition with
speed protection system. These special
conditions pertain to their effects on the
structural performance of the airplane.
The applicable airworthiness
regulations do not contain adequate or
appropriate safety standards for these
design features. These 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.
EFFECTIVE DATE: April 4, 2007.
FOR FURTHER INFORMATION CONTACT: Tom
Rodriguez, FAA, International Branch,
ANM–116, Transport Airplane
Directorate, Aircraft Certification
Service, 1601 Lind Avenue, SW.,
Renton, Washington 98057–3356;
telephone (425) 227–1503; facsimile
(425) 227–1320.
SUPPLEMENTARY INFORMATION:
Background
On June 4, 2002, Dassault Aviation, 9
rond Point des Champs Elysees, 75008,
Paris, France, applied for an FAA type
certificate for its new Model Falcon 7X
airplane. The Dassault Model Falcon 7X
airplane is a 19 passenger transport
category airplane powered by three aft
mounted Pratt & Whitney PW307A high
bypass ratio turbofan engines.
Maximum takeoff weight will be 63,700
pounds, and maximum certified altitude
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will be 51,000 feet with a range of 5,700
nautical miles. The airplane is operated
using a fly-by-wire (FBW) primary flight
control system. This will be the first
application of a FBW primary flight
control system in an airplane primarily
intended for private/corporate use.
The Dassault Aviation Model Falcon
7X design incorporates equipment that
was not envisioned when part 25 was
created. This equipment affects sudden
engine stoppage, operation without
normal electrical power, and dive speed
definition with speed protection system.
Therefore, special conditions are
required that provide the level of safety
equivalent to that established by the
regulations.
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Type Certification Basis
Under the provisions of 14 CFR 21.17,
Dassault Aviation must show that the
Model Falcon 7X airplane meets the
applicable provisions of 14 CFR part 25,
as amended by Amendments 25–1
through 25–108.
If the Administrator finds that the
applicable airworthiness regulations do
not contain adequate or appropriate
safety standards for the Model Falcon
7X airplane because of novel or unusual
design features, special conditions are
prescribed under the provisions of
§ 21.16.
In addition to the applicable
airworthiness regulations and special
conditions, the Dassault Model Falcon
7X airplane 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.
The FAA issues special conditions, as
defined in § 11.19, under § 11.38, and
they become part of the type
certification basis under § 21.17(a)(2).
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 novel or unusual
design feature, the special conditions
would also apply to the other model
under § 21.101.
Novel or Unusual Design Features
The Dassault Aviation Model Falcon
7X airplane will incorporate novel or
unusual design features that will affect:
• Sudden engine stoppage.
• Operation without normal electrical
power.
• Dive speed definition with speed
protection system.
These special conditions address
equipment which may affect the
airplane’s structural performance, either
directly or as a result of failure or
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14:18 Apr 11, 2007
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malfunction. These special conditions
are identical or nearly identical to those
previously required for type
certification of other airplane models.
Discussion
Because of these rapid improvements
in airplane technology, the applicable
airworthiness regulations do not contain
adequate or appropriate safety standards
for these design features. Therefore, in
addition to the requirements of part 25,
subparts C and D, the following special
conditions apply.
Special Conditions for Sudden Engine
Stoppage
The Dassault Model Falcon 7X will
have high-bypass ratio turbofan engines.
Engines of this size were not envisioned
when § 25.361, pertaining to loads
imposed by engine seizure, was adopted
in 1965. Worst case engine seizure
events become increasingly more severe
with increasing engine size because of
the higher inertia of the rotating
components.
Section 25.361(b)(1) requires that for
turbine engine installations, the engine
mounts and the supporting structures
must be designed to withstand a ‘‘limit
engine torque load imposed by sudden
engine stoppage due to malfunction or
structural failure.’’ Limit loads are
expected to occur about once in the
lifetime of any airplane. Section 25.305
requires that supporting structures be
able to support limit loads without
detrimental permanent deformation,
meaning that supporting structures
should remain serviceable after a limit
load event.
Since adoption of § 25.361(b)(1), the
size, configuration, and failure modes of
jet engines have changed considerably.
Current engines are much larger and are
designed with large bypass fans. In the
event of a structural failure, these
engines are capable of producing much
higher transient loads on the engine
mounts and supporting structures.
As a result, modern high bypass
engines are subject to certain rare-butsevere engine seizure events. Service
history shows that such events occur far
less frequently than limit load events.
Although it is important for the airplane
to be able to support such rare loads
safely without failure, it is unrealistic to
expect that no permanent deformation
will occur.
Given this situation, the Aviation
Rulemaking Advisory Committee
(ARAC) proposed a design standard for
today’s large engines. For the
commonly-occurring deceleration
events, the proposed standard requires
engine mounts and structures to support
maximum torques without detrimental
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18373
permanent deformation. For the rarebut-severe engine seizure events such as
loss of any fan, compressor, or turbine
blade, the proposed standard requires
engine mounts and structures to support
maximum torques without failure, but
allows for some deformation in the
structure.
The FAA concludes that modern large
engines, including those on the Model
Falcon 7X, are novel and unusual
compared to those envisioned when
§ 25.361(b)(1) was adopted and thus
warrant a special condition. The special
condition contains design criteria
recommended by ARAC. The ARAC
proposal was to revise the wording of
§ 25.361(b), including §§ 25.361(b)(1)
and (b)(2), removing language pertaining
to structural failures and moving it to a
separate requirement that discusses the
reduced factors of safety that apply to
these failures.
Special Conditions for Operation
Without Normal Electrical Power
The Dassault Aviation Model Falcon
7X airplane will have electrical and
electronic systems which perform
critical functions. The Model Falcon 7X
airplane is a fly-by-wire control system
that requires a continuous source of
electrical power for the flight control
system to remain operable, since the
loss of all electrical power may be
catastrophic to the airplane. The
airworthiness standards of part 25 do
not contain adequate or appropriate
standards for the protection of the
Electronic Flight Control System from
the adverse effects of operations without
normal electrical power.
Section 25.1351(d), ‘‘Operation
without normal electrical power,’’
requires safe operation in visual flight
rule (VFR) conditions for at least five
minutes with inoperative normal power.
This rule was structured around a
traditional design utilizing mechanical
control cables for flight control surfaces
and the pilot controls. Such traditional
designs enable the flightcrew to
maintain control of the airplane, while
providing time to sort out the electrical
failure, re-start the engines if necessary,
and re-establish some of the electrical
power generation capability.
The Dassault Aviation Model Falcon
7X airplane, however, will utilize an
Electronic Flight Control System for the
pitch and yaw control (elevator,
stabilizer, and rudder). There is no
mechanical linkage between the pilot
controls and these flight control
surfaces. Pilot control inputs are
converted to electrical signals, which
are processed and then transmitted via
wires to the control surface actuators. At
the control surface actuators, the
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electrical signals are converted to an
actuator command, which moves the
control surface.
To maintain the same level of safety
as that associated with traditional
designs, the Dassault Model 7X
airplanes with electronic flight controls
must not be time limited in their
operation, including being without the
normal source of electrical power
generated by the engine or the Auxiliary
Power Unit (APU) generated electrical
power.
Service experience has shown that the
loss of all electrical power generated by
the airplane’s engine generators or APU
is not extremely improbable. Thus, it
must be demonstrated that the airplane
can continue safe flight and landing—
including steering and braking on
ground for airplanes using steer/brakeby-wire—after total loss of normal
electrical power with the use of its
emergency electrical power systems.
These emergency electrical power
systems must be able to power loads
that are essential for continued safe
flight and landing.
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Special Conditions for Dive Speed
Definition With Speed Protection
System
Dassault Aviation proposed to reduce
the speed margin between VC and VD
required by § 25.335(b), based on the
incorporation of a high speed protection
system in the Model Falcon 7X flight
control laws. The Falcon 7X is equipped
with a high speed protection system
which limits nose down pilot authority
at speeds above VC/MC and prevents the
airplane from actually performing the
maneuver required under § 25.335(b)(1).
Section 25.335(b)(1) is an analytical
envelope condition which was
originally adopted in Part 4b of the Civil
Air Regulations to provide an acceptable
speed margin between design cruise
speed and design dive speed. Freedom
from flutter and airframe design loads is
affected by the design dive speed. While
the initial condition for the upset
specified in the rule is 1g level flight,
protection is afforded for other
inadvertent overspeed conditions as
well. Section 25.335(b)(1) is intended as
a conservative enveloping condition for
all potential overspeed conditions,
including non-symmetric ones.
To establish that all potential
overspeed conditions are enveloped, the
applicant will demonstrate that the dive
speed will not be exceeded during pilotinduced or gust-induced upsets in nonsymmetric attitudes.
In addition, the high speed protection
system in the Falcon 7X must have a
high level of reliability.
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Jkt 211001
Discussion of Comments
Notice of proposed special conditions
No. 25–07–07–SC for the Dassault
Aviation Model Falcon 7X airplanes
was published in the Federal Register
on March 1, 2007 (72 FR 9273). No
comments were received, and the
special conditions are adopted as
proposed.
Applicability
As discussed above, these special
conditions are applicable to the Dassault
Aviation Model Falcon 7X airplane.
Should Dassault Aviation apply at a
later date for a change to the type
certificate to include another model on
the same type certificate incorporating
the same novel or unusual design
features, these special conditions would
apply to that model as well.
For Final Special Conditions Effective
Upon Issuance
Under standard practice, the effective
date of final special conditions would
be 30 days after the date of publication
in the Federal Register; however, as the
certification date for the Dassault Model
Falcon 7X is imminent, the FAA finds
that good cause exists to make these
special conditions effective upon
issuance.
Conclusion
This action affects only certain novel
or unusual design features on model
Falcon 7X 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 Special Conditions
Accordingly, pursuant to the
authority delegated to me by the
Administrator, the following special
conditions are issued as part of the type
certification basis for Dassault Aviation
Model Falcon 7X airplanes.
1. Sudden Engine Stoppage
In lieu of the requirements of
§ 25.361(b) the following special
condition applies:
(a) For turbine engine installations,
the engine mounts, pylons and adjacent
supporting airframe structure must be
designed to withstand 1 g level flight
loads acting simultaneously with the
maximum limit torque loads imposed
by each of the following:
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(1) Sudden engine deceleration due to
a malfunction which could result in a
temporary loss of power or thrust; and
(2) The maximum acceleration of the
engine.
(b) For auxiliary power unit
installations, the power unit mounts
and adjacent supporting airframe
structure must be designed to withstand
1 g level flight loads acting
simultaneously with the maximum limit
torque loads imposed by each of the
following:
(1) Sudden auxiliary power unit
deceleration due to malfunction or
structural failure; and
(2) The maximum acceleration of the
power unit.
(c) For engine supporting structures,
an ultimate loading condition must be
considered that combines 1 g flight
loads with the transient dynamic loads
resulting from:
(1) The loss of any fan, compressor, or
turbine blade; and separately
(2) where applicable to a specific
engine design, any other engine
structural failure that results in higher
loads.
(d) The ultimate loads developed from
the conditions specified in paragraphs
(c)(1) and (2) above are to be multiplied
by a factor of 1.0 when applied to
engine mounts and pylons and
multiplied by a factor of 1.25 when
applied to adjacent supporting airframe
structure. In addition, the airplane must
be capable of continued safe flight
considering the aerodynamic effects on
controllability due to any permanent
deformation that results from the
conditions specified in paragraph (c),
above.
2. Operation Without Normal Electrical
Power
In lieu of the requirements of 14 CFR
25.1351(d), the following special
condition applies:
It must be demonstrated by test or
combination of test and analysis that the
airplane can continue safe flight and
landing with inoperative normal engine
and APU generator electrical power (i.e.,
electrical power sources, excluding the
battery and any other standby electrical
sources). The airplane operation should
be considered at the critical phase of
flight and include the ability to restart
the engines and maintain flight for the
maximum diversion time capability
being certified.
3. Dive Speed Definition With Speed
Protection System
In lieu of the requirements of
§ 25.335(b)(1)—if the flight control
system includes functions which act
automatically to initiate recovery before
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the end of the 20 second period
specified in § 25.335(b)(1)—the
following special condition applies.
The greater of the speeds resulting
from the conditions of paragraphs (a)
and (b), below, must be used.
(a) From an initial condition of
stabilized flight at VC/MC, the airplane
is upset so as to take up a new flight
path 7.5 degrees below the initial path.
Control application, up to full authority,
is made to try and maintain this new
flight path. Twenty seconds after
initiating the upset, manual recovery is
made at a load factor of 1.5 g (0.5
acceleration increment) or such greater
load factor that is automatically applied
by the system with the pilot’s pitch
control neutral. The speed increase
occurring in this maneuver may be
calculated, if reliable or conservative
aerodynamic data is used. Power, as
specified in § 25.175(b)(1)(iv), is
assumed until recovery is made, at
which time power reduction and the use
of pilot controlled drag devices may be
used.
(b) From a speed below VC/MC with
power to maintain stabilized level flight
at this speed, the airplane is upset so as
to accelerate through VC/MC at a flight
path 15 degrees below the initial path—
or at the steepest nose down attitude
that the system will permit with full
control authority if less than 15 degrees.
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Note: The pilot’s controls may be in the
neutral position after reaching VC/MC and
before recovery is initiated.
(c) Recovery may be initiated three
seconds after operation of high speed
warning system by application of a load
of 1.5 g (0.5 acceleration increment) or
such greater load factor that is
automatically applied by the system
with the pilot’s pitch control neutral.
Power may be reduced simultaneously.
All other means of decelerating the
airplane, the use of which is authorized
up to the highest speed reached in the
maneuver, may be used. The interval
between successive pilot actions must
not be less than one second.
(d) The applicant must also
demonstrate that the design dive speed,
established above, will not be exceeded
during pilot-induced or gust-induced
upsets in non-symmetric attitudes.
(e) The occurrence of any failure
condition that would reduce the
capability of the overspeed protection
system must be improbable (less than
10¥5 per flight hour).
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15:09 Apr 11, 2007
Jkt 211001
Issued in Renton, Washington, on April 4,
2007.
Stephen P. Boyd,
Acting Manager, Transport Airplane
Directorate, Aircraft Certification Service.
[FR Doc. E7–6889 Filed 4–11–07; 8:45 am]
BILLING CODE 4910–13–P
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
RIN 2120–AA64
Airworthiness Directives; Hartzell
Propeller Inc. Model HC–E4A–3( )/
E10950( ) Propellers
Federal Aviation
Administration (FAA), Department of
Transportation (DOT).
ACTION: Final rule; request for
comments.
AGENCY:
SUMMARY: The FAA is adopting a new
airworthiness directive (AD) for Hartzell
Propeller Inc. model HC–E4A–3( )/
E10950( ) propellers. This AD requires
initial and repetitive inspections and
rework of the propeller blade retention
radius, and replacement of the propeller
blade thrust bearing, for each blade.
This AD results from reports of
excessive propeller vibration and of
damaged or broken propeller blade
thrust bearings found during routine
and investigative propeller disassembly.
We are issuing this AD to prevent
propeller blade separation, damage to
the airplane, and possible loss of
airplane control.
DATES: This AD becomes effective April
27, 2007. The Director of the Federal
Register approved the incorporation by
reference of certain publications listed
in the regulations as of April 27, 2007.
We must receive any comments on
this AD by June 11, 2007.
ADDRESSES: Use one of the following
addresses to comment on this AD:
• DOT Docket Web site: Go to
https://dms.dot.gov and follow the
instructions for sending your comments
electronically.
• Government-wide rulemaking Web
site: Go to https://www.regulations.gov
and follow the instructions for sending
your comments electronically.
• Mail: Docket Management Facility;
U.S. Department of Transportation, 400
Seventh Street, SW., Nassif Building,
Room PL–401, Washington, DC 20590–
0001.
Frm 00033
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• Fax: (202) 493–2251.
• Hand Delivery: Room PL–401 on
the plaza level of the Nassif Building,
400 Seventh Street, SW., Washington,
DC, between 9 a.m. and 5 p.m., Monday
through Friday, except Federal holidays.
Contact Hartzell Propeller Inc.
Technical Publications Department, One
Propeller Place, Piqua, OH 45356;
telephone (937) 778–4200; fax (937)
778–4391, for the service information
identified in this AD.
Tim
Smyth, Aerospace Engineer, Chicago
Aircraft Certification Office, FAA, Small
Airplane Directorate, 2300 East Devon
Avenue, Des Plaines, IL 60018; e-mail:
tim.smyth@faa.gov; telephone: (847)
294–7132; fax: (847) 294–7834.
FOR FURTHER INFORMATION CONTACT:
[Docket No. FAA–2007–27552; Directorate
Identifier 2007–NE–11–AD; Amendment 39–
15019; AD 2007–08–02]
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We have
received reports of excessive propeller
vibration, and of damaged or broken
propeller blade thrust bearings on
Hartzell Propeller Inc. model HC–E4A–
3( )/E10950( ) propellers found during
routine and investigative propeller
disassembly. At least 15 propellers have
been reported with broken propeller
blade thrust bearings. During teardowns,
instances of bearing failures have been
progressively more severe, with more
internal damage to the hub noted.
Service history shows the propellers can
safely accumulate 2,000 operating hours
time-since-overhaul (TSO) before the
unsafe conditions start to appear. A
broken thrust bearing can lead to
damage to the propeller hub and blade
shank, and blade separation from the
hub. These damaged or broken parts can
also lead to damage to the internal
propeller pitch change mechanism,
resulting in loss of propeller pitch
control or in difficulty in feathering the
propeller. This condition, if not
corrected, could result in propeller
blade separation, damage to the
airplane, and possible loss of airplane
control. Repairing the propeller blade
retention radius using the instructions
cited in Hartzell Propeller Inc. Service
Bulletin (SB) No. HC–SB–61–287,
Revision 2, dated October 24, 2006,
allows the propeller to safely operate for
3,000 hours before requiring bearing
replacement.
SUPPLEMENTARY INFORMATION:
Relevant Service Information
We reviewed and approved the
technical contents of Hartzell Propeller
Inc. SB No. HC–SB–61–287, Revision 2,
dated October 24, 2006. That SB
describes procedures for initial and
repetitive propeller blade inspection,
rework, and thrust bearing replacement,
for each blade.
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]]>Agencies
[Federal Register Volume 72, Number 70 (Thursday, April 12, 2007)]
[Rules and Regulations]
[Pages 18372-18375]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E7-6889]
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM371; Special Conditions No. 25-350-SC]
Special Conditions: Dassault Aviation Model Falcon 7X Airplane;
Sudden Engine Stoppage, Operation Without Normal Electrical Power, and
Dive Speed Definition With Speed Protection System
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions.
-----------------------------------------------------------------------
SUMMARY: These special conditions are issued for the Dassault Aviation
Model Falcon 7X Airplane; Sudden Engine Stoppage, Operation Without
Normal Electrical Power, and Dive Speed Definition with Speed
Protection System. This airplane will have novel or unusual design
features that include engine size and torque load, which affect sudden
engine stoppage; electrical and electronic systems which perform
critical functions, which affect operation without normal electrical
power; and dive speed definition with speed protection system. These
special conditions pertain to their effects on the structural
performance of the airplane. The applicable airworthiness regulations
do not contain adequate or appropriate safety standards for these
design features. These 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.
EFFECTIVE DATE: April 4, 2007.
FOR FURTHER INFORMATION CONTACT: Tom Rodriguez, FAA, International
Branch, ANM-116, Transport Airplane Directorate, Aircraft Certification
Service, 1601 Lind Avenue, SW., Renton, Washington 98057-3356;
telephone (425) 227-1503; facsimile (425) 227-1320.
SUPPLEMENTARY INFORMATION:
Background
On June 4, 2002, Dassault Aviation, 9 rond Point des Champs
Elysees, 75008, Paris, France, applied for an FAA type certificate for
its new Model Falcon 7X airplane. The Dassault Model Falcon 7X airplane
is a 19 passenger transport category airplane powered by three aft
mounted Pratt & Whitney PW307A high bypass ratio turbofan engines.
Maximum takeoff weight will be 63,700 pounds, and maximum certified
altitude
[[Page 18373]]
will be 51,000 feet with a range of 5,700 nautical miles. The airplane
is operated using a fly-by-wire (FBW) primary flight control system.
This will be the first application of a FBW primary flight control
system in an airplane primarily intended for private/corporate use.
The Dassault Aviation Model Falcon 7X design incorporates equipment
that was not envisioned when part 25 was created. This equipment
affects sudden engine stoppage, operation without normal electrical
power, and dive speed definition with speed protection system.
Therefore, special conditions are required that provide the level of
safety equivalent to that established by the regulations.
Type Certification Basis
Under the provisions of 14 CFR 21.17, Dassault Aviation must show
that the Model Falcon 7X airplane meets the applicable provisions of 14
CFR part 25, as amended by Amendments 25-1 through 25-108.
If the Administrator finds that the applicable airworthiness
regulations do not contain adequate or appropriate safety standards for
the Model Falcon 7X airplane because of novel or unusual design
features, special conditions are prescribed under the provisions of
Sec. 21.16.
In addition to the applicable airworthiness regulations and special
conditions, the Dassault Model Falcon 7X airplane 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.
The FAA issues special conditions, as defined in Sec. 11.19, under
Sec. 11.38, and they become part of the type certification basis under
Sec. 21.17(a)(2).
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 novel or
unusual design feature, the special conditions would also apply to the
other model under Sec. 21.101.
Novel or Unusual Design Features
The Dassault Aviation Model Falcon 7X airplane will incorporate
novel or unusual design features that will affect:
Sudden engine stoppage.
Operation without normal electrical power.
Dive speed definition with speed protection system.
These special conditions address equipment which may affect the
airplane's structural performance, either directly or as a result of
failure or malfunction. These special conditions are identical or
nearly identical to those previously required for type certification of
other airplane models.
Discussion
Because of these rapid improvements in airplane technology, the
applicable airworthiness regulations do not contain adequate or
appropriate safety standards for these design features. Therefore, in
addition to the requirements of part 25, subparts C and D, the
following special conditions apply.
Special Conditions for Sudden Engine Stoppage
The Dassault Model Falcon 7X will have high-bypass ratio turbofan
engines. Engines of this size were not envisioned when Sec. 25.361,
pertaining to loads imposed by engine seizure, was adopted in 1965.
Worst case engine seizure events become increasingly more severe with
increasing engine size because of the higher inertia of the rotating
components.
Section 25.361(b)(1) requires that for turbine engine
installations, the engine mounts and the supporting structures must be
designed to withstand a ``limit engine torque load imposed by sudden
engine stoppage due to malfunction or structural failure.'' Limit loads
are expected to occur about once in the lifetime of any airplane.
Section 25.305 requires that supporting structures be able to support
limit loads without detrimental permanent deformation, meaning that
supporting structures should remain serviceable after a limit load
event.
Since adoption of Sec. 25.361(b)(1), the size, configuration, and
failure modes of jet engines have changed considerably. Current engines
are much larger and are designed with large bypass fans. In the event
of a structural failure, these engines are capable of producing much
higher transient loads on the engine mounts and supporting structures.
As a result, modern high bypass engines are subject to certain
rare-but-severe engine seizure events. Service history shows that such
events occur far less frequently than limit load events. Although it is
important for the airplane to be able to support such rare loads safely
without failure, it is unrealistic to expect that no permanent
deformation will occur.
Given this situation, the Aviation Rulemaking Advisory Committee
(ARAC) proposed a design standard for today's large engines. For the
commonly-occurring deceleration events, the proposed standard requires
engine mounts and structures to support maximum torques without
detrimental permanent deformation. For the rare-but-severe engine
seizure events such as loss of any fan, compressor, or turbine blade,
the proposed standard requires engine mounts and structures to support
maximum torques without failure, but allows for some deformation in the
structure.
The FAA concludes that modern large engines, including those on the
Model Falcon 7X, are novel and unusual compared to those envisioned
when Sec. 25.361(b)(1) was adopted and thus warrant a special
condition. The special condition contains design criteria recommended
by ARAC. The ARAC proposal was to revise the wording of Sec.
25.361(b), including Sec. Sec. 25.361(b)(1) and (b)(2), removing
language pertaining to structural failures and moving it to a separate
requirement that discusses the reduced factors of safety that apply to
these failures.
Special Conditions for Operation Without Normal Electrical Power
The Dassault Aviation Model Falcon 7X airplane will have electrical
and electronic systems which perform critical functions. The Model
Falcon 7X airplane is a fly-by-wire control system that requires a
continuous source of electrical power for the flight control system to
remain operable, since the loss of all electrical power may be
catastrophic to the airplane. The airworthiness standards of part 25 do
not contain adequate or appropriate standards for the protection of the
Electronic Flight Control System from the adverse effects of operations
without normal electrical power.
Section 25.1351(d), ``Operation without normal electrical power,''
requires safe operation in visual flight rule (VFR) conditions for at
least five minutes with inoperative normal power. This rule was
structured around a traditional design utilizing mechanical control
cables for flight control surfaces and the pilot controls. Such
traditional designs enable the flightcrew to maintain control of the
airplane, while providing time to sort out the electrical failure, re-
start the engines if necessary, and re-establish some of the electrical
power generation capability.
The Dassault Aviation Model Falcon 7X airplane, however, will
utilize an Electronic Flight Control System for the pitch and yaw
control (elevator, stabilizer, and rudder). There is no mechanical
linkage between the pilot controls and these flight control surfaces.
Pilot control inputs are converted to electrical signals, which are
processed and then transmitted via wires to the control surface
actuators. At the control surface actuators, the
[[Page 18374]]
electrical signals are converted to an actuator command, which moves
the control surface.
To maintain the same level of safety as that associated with
traditional designs, the Dassault Model 7X airplanes with electronic
flight controls must not be time limited in their operation, including
being without the normal source of electrical power generated by the
engine or the Auxiliary Power Unit (APU) generated electrical power.
Service experience has shown that the loss of all electrical power
generated by the airplane's engine generators or APU is not extremely
improbable. Thus, it must be demonstrated that the airplane can
continue safe flight and landing--including steering and braking on
ground for airplanes using steer/brake-by-wire--after total loss of
normal electrical power with the use of its emergency electrical power
systems. These emergency electrical power systems must be able to power
loads that are essential for continued safe flight and landing.
Special Conditions for Dive Speed Definition With Speed Protection
System
Dassault Aviation proposed to reduce the speed margin between
VC and VD required by Sec. 25.335(b), based on
the incorporation of a high speed protection system in the Model Falcon
7X flight control laws. The Falcon 7X is equipped with a high speed
protection system which limits nose down pilot authority at speeds
above VC/MC and prevents the airplane from
actually performing the maneuver required under Sec. 25.335(b)(1).
Section 25.335(b)(1) is an analytical envelope condition which was
originally adopted in Part 4b of the Civil Air Regulations to provide
an acceptable speed margin between design cruise speed and design dive
speed. Freedom from flutter and airframe design loads is affected by
the design dive speed. While the initial condition for the upset
specified in the rule is 1g level flight, protection is afforded for
other inadvertent overspeed conditions as well. Section 25.335(b)(1) is
intended as a conservative enveloping condition for all potential
overspeed conditions, including non-symmetric ones.
To establish that all potential overspeed conditions are enveloped,
the applicant will demonstrate that the dive speed will not be exceeded
during pilot-induced or gust-induced upsets in non-symmetric attitudes.
In addition, the high speed protection system in the Falcon 7X must
have a high level of reliability.
Discussion of Comments
Notice of proposed special conditions No. 25-07-07-SC for the
Dassault Aviation Model Falcon 7X airplanes was published in the
Federal Register on March 1, 2007 (72 FR 9273). No comments were
received, and the special conditions are adopted as proposed.
Applicability
As discussed above, these special conditions are applicable to the
Dassault Aviation Model Falcon 7X airplane. Should Dassault Aviation
apply at a later date for a change to the type certificate to include
another model on the same type certificate incorporating the same novel
or unusual design features, these special conditions would apply to
that model as well.
For Final Special Conditions Effective Upon Issuance
Under standard practice, the effective date of final special
conditions would be 30 days after the date of publication in the
Federal Register; however, as the certification date for the Dassault
Model Falcon 7X is imminent, the FAA finds that good cause exists to
make these special conditions effective upon issuance.
Conclusion
This action affects only certain novel or unusual design features
on model Falcon 7X 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 Special Conditions
Accordingly, pursuant to the authority delegated to me by the
Administrator, the following special conditions are issued as part of
the type certification basis for Dassault Aviation Model Falcon 7X
airplanes.
1. Sudden Engine Stoppage
In lieu of the requirements of Sec. 25.361(b) the following
special condition applies:
(a) For turbine engine installations, the engine mounts, pylons and
adjacent supporting airframe structure must be designed to withstand 1
g level flight loads acting simultaneously with the maximum limit
torque loads imposed by each of the following:
(1) Sudden engine deceleration due to a malfunction which could
result in a temporary loss of power or thrust; and
(2) The maximum acceleration of the engine.
(b) For auxiliary power unit installations, the power unit mounts
and adjacent supporting airframe structure must be designed to
withstand 1 g level flight loads acting simultaneously with the maximum
limit torque loads imposed by each of the following:
(1) Sudden auxiliary power unit deceleration due to malfunction or
structural failure; and
(2) The maximum acceleration of the power unit.
(c) For engine supporting structures, an ultimate loading condition
must be considered that combines 1 g flight loads with the transient
dynamic loads resulting from:
(1) The loss of any fan, compressor, or turbine blade; and
separately
(2) where applicable to a specific engine design, any other engine
structural failure that results in higher loads.
(d) The ultimate loads developed from the conditions specified in
paragraphs (c)(1) and (2) above are to be multiplied by a factor of 1.0
when applied to engine mounts and pylons and multiplied by a factor of
1.25 when applied to adjacent supporting airframe structure. In
addition, the airplane must be capable of continued safe flight
considering the aerodynamic effects on controllability due to any
permanent deformation that results from the conditions specified in
paragraph (c), above.
2. Operation Without Normal Electrical Power
In lieu of the requirements of 14 CFR 25.1351(d), the following
special condition applies:
It must be demonstrated by test or combination of test and analysis
that the airplane can continue safe flight and landing with inoperative
normal engine and APU generator electrical power (i.e., electrical
power sources, excluding the battery and any other standby electrical
sources). The airplane operation should be considered at the critical
phase of flight and include the ability to restart the engines and
maintain flight for the maximum diversion time capability being
certified.
3. Dive Speed Definition With Speed Protection System
In lieu of the requirements of Sec. 25.335(b)(1)--if the flight
control system includes functions which act automatically to initiate
recovery before
[[Page 18375]]
the end of the 20 second period specified in Sec. 25.335(b)(1)--the
following special condition applies.
The greater of the speeds resulting from the conditions of
paragraphs (a) and (b), below, must be used.
(a) From an initial condition of stabilized flight at
VC/MC, the airplane is upset so as to take up a
new flight path 7.5 degrees below the initial path. Control
application, up to full authority, is made to try and maintain this new
flight path. Twenty seconds after initiating the upset, manual recovery
is made at a load factor of 1.5 g (0.5 acceleration increment) or such
greater load factor that is automatically applied by the system with
the pilot's pitch control neutral. The speed increase occurring in this
maneuver may be calculated, if reliable or conservative aerodynamic
data is used. Power, as specified in Sec. 25.175(b)(1)(iv), is assumed
until recovery is made, at which time power reduction and the use of
pilot controlled drag devices may be used.
(b) From a speed below VC/MC with power to
maintain stabilized level flight at this speed, the airplane is upset
so as to accelerate through VC/MC at a flight
path 15 degrees below the initial path--or at the steepest nose down
attitude that the system will permit with full control authority if
less than 15 degrees.
Note: The pilot's controls may be in the neutral position after
reaching VC/MC and before recovery is
initiated.
(c) Recovery may be initiated three seconds after operation of high
speed warning system by application of a load of 1.5 g (0.5
acceleration increment) or such greater load factor that is
automatically applied by the system with the pilot's pitch control
neutral. Power may be reduced simultaneously. All other means of
decelerating the airplane, the use of which is authorized up to the
highest speed reached in the maneuver, may be used. The interval
between successive pilot actions must not be less than one second.
(d) The applicant must also demonstrate that the design dive speed,
established above, will not be exceeded during pilot-induced or gust-
induced upsets in non-symmetric attitudes.
(e) The occurrence of any failure condition that would reduce the
capability of the overspeed protection system must be improbable (less
than 10-5 per flight hour).
Issued in Renton, Washington, on April 4, 2007.
Stephen P. Boyd,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. E7-6889 Filed 4-11-07; 8:45 am]
BILLING CODE 4910-13-P
