[Federal Register Volume 72, Number 70 (Thursday, April 12, 2007)]
[Rules and Regulations]
[Pages 18372-18375]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-6889]


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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

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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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