[Federal Register: March 1, 2007 (Volume 72, Number 40)]
[Proposed Rules]
[Page 9273-9276]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr01mr07-15]
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Proposed Rules
Federal Register
________________________________________________________________________
This section of the FEDERAL REGISTER contains notices to the public of
the proposed issuance of rules and regulations. The purpose of these
notices is to give interested persons an opportunity to participate in
the rule making prior to the adoption of the final rules.
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[[Page 9273]]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM371; Notice No. 25-07-07-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: Notice of proposed special conditions.
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SUMMARY: This action proposes special conditions for the Dassault
Aviation Model Falcon 7X airplane. This airplane will have novel or
unusual design features when compared to the state of technology
envisioned in the airworthiness standards for transport category
airplanes. These design features 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 proposed 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 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: We must receive your comments by March 21, 2007.
ADDRESSES: You must mail two copies of your comments to: Federal
Aviation Administration, Transport Airplane Directorate, Attention:
Rules Docket (ANM-113), Docket No. NM371, 1601 Lind Avenue SW., Renton,
Washington 98057-3356. You may deliver two copies to the Transport
Airplane Directorate at the above address. You must mark your comments:
Docket No. NM371. You can inspect comments in the Rules Docket
weekdays, except Federal holidays, between 7:30 a.m. and 4 p.m.
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:
Comments Invited
We invite interested people to participate in this rulemaking by
submitting 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 file in the docket all comments we receive as well as a
report summarizing each substantive public contact with FAA personnel
concerning these proposed special conditions. You can inspect the
docket before and after the comment closing date. If you wish to review
the docket in person, go to the address in the ADDRESSES section of
this notice between 7:30 a.m. and 4 p.m., Monday through Friday, except
Federal holidays.
We will consider all comments we receive on or before the closing
date for comments. We will consider comments filed late, if it is
possible to do so without incurring expense or delay. We may change the
proposed special conditions in light of the comments we receive.
If you want the FAA to acknowledge receipt of your comments on this
proposal, include with your comments a pre-addressed, stamped postcard
on which the docket number appears. We will stamp the date on the
postcard and mail it back to you.
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 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 a private/corporate use airplane.
The Dassault Aviation Model Falcon 7X design incorporates equipment
that was not envisioned when part 25 was created. This equipment
affects the 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. In addition, the
FAA must issue a finding of regulatory adequacy under section 611 of
Public Law 93-574, the ``Noise Control Act of 1972.''
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
[[Page 9274]]
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 the
following novel or unusual design features:
Sudden engine stoppage.
Operation without normal electrical power.
Dive speed definition with speed protection system.
Because of these rapid improvements in airplane technology, the
applicable airworthiness regulations do not contain adequate or
appropriate safety standards for these design features. These proposed
special conditions address equipment which may affect the airplane's
structural performance, either directly or as a result of failure or
malfunction. These proposed special conditions are identical or nearly
identical to those previously required for type certification of other
airplane models. Additional special conditions will be issued for other
novel or unusual design features of the Dassault Model Falcon 7X
airplane. Those additional special conditions will pertain to the
following topics:
Side stick controllers;
Electronic flight control system: lateral-directional and
longitudinal stability, low energy awareness.
Electronic flight control system: flight control surface
position awareness, and
Electronic flight control system: flight characteristics
compliance via the handling qualities rating method (HQRM);
Flight envelope protection: general limiting requirements,
Flight envelope protection: high incidence protection
function,
Flight envelope protection: normal load factor (g)
limiting,
Flight envelope protection: pitch, roll, and high speed
limiting functions.
Final special conditions have been issued for the Model Falcon 7X
with the novel or unusual design feature pertaining to Pilot
Compartment View-Hydrophobic Coatings in Lieu of Windshield Wipers
(January 10, 2007; 72 FR 1135). Special conditions have been proposed
for the Model Falcon 7X with the novel or unusual design features
pertaining to Interaction of Systems and Structures, Limit Pilot
Forces, and High Intensity Radiated Fields (HIRF) (October 18, 2006; 71
FR 61427).
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.
Proposed 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, Aviation Rulemaking Advisory Committee (ARAC)
has proposed a design standard for today's large engines. For the
commonly-occurring deceleration events, the proposed standard would
require 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 would require 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 proposed special condition contains design criteria
recommended by ARAC. The ARAC proposal would 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.
Proposed 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 electrical signals are
converted to an actuator command, which moves the control surface.
[[Page 9275]]
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 its 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.
Proposed Special Conditions for Dive Speed Definition With Speed
Protection System
Dassault Aviation proposes 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 would 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.
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 incorporating the same novel or unusual design features,
these special conditions would apply to that model as well.
Conclusion
This action affects only certain novel or unusual design features
of the Dassault Aviation Model Falcon 7X airplane. It is not a rule of
general applicability, and it affects only the applicant which applied
to the FAA for approval of these features on the airplane.
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, pursuant to the authority delegated to me by the
Administrator, the following special conditions are issued as part of
the type certification basis for the Dassault Aviation Model Falcon 7X
airplane.
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 1g
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 1g 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 1g 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 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
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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 1.5g (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 February 23, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. E7-3582 Filed 2-28-07; 8:45 am]
BILLING CODE 4910-13-P