Special Conditions: Dassault Falcon Model 900 and 900EX Airplanes; Interaction of Systems and Structures, 54923-54926 [2011-22631]

Agencies

• Federal Aviation Administration
• DEPARTMENT OF TRANSPORTATION

[Federal Register Volume 76, Number 172 (Tuesday, September 6, 2011)]
[Rules and Regulations]
[Pages 54923-54926]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-22631]



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Federal Register / Vol. 76, No. 172 / Tuesday, September 6, 2011 / 
Rules and Regulations

[[Page 54923]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM463; Special Conditions No. 25-443-SC]


Special Conditions: Dassault Falcon Model 900 and 900EX 
Airplanes; Interaction of Systems and Structures

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions; request for comments.

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SUMMARY: These special conditions are issued for the Dassault Falcon 
Model 900 and 900EX airplanes. These airplanes, as modified by Aviation 
Partners Incorporated (API), will have a novel or unusual design 
feature associated with the interaction of systems and structures 
regarding installation of an automated wing-load-alleviation system. 
The applicable airworthiness regulations do not contain adequate or 
appropriate safety standards for this design feature. For the Dassault 
900 and 900EX models with winglets, failure of the wing-load-
alleviation system can result in a factor of safety (FS) below 1.5 as 
required. 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.

DATES: The effective date of these special conditions is August 29, 
2011. We must receive your comments by October 6, 2011.

ADDRESSES: You must mail two copies of your comments to: Federal 
Aviation Administration, Transport Airplane Directorate, Attn: Rules 
Docket (ANM-113), Docket No. NM463, 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. NM463. 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: Todd Martin, Airframe/Cabin Safety 
Branch, Transport Airplane Directorate, Aircraft Certification Service, 
1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone (425) 
227-1178; facsimile (425) 227-1232.

SUPPLEMENTARY INFORMATION: The FAA has determined that notice of, and 
opportunity for prior public comment on, these special conditions is 
impracticable because these procedures would significantly delay 
issuance of the design approval and thus delivery of the affected 
aircraft. In addition, the substance of these special conditions has 
been subject to the public-comment process in several previous 
instances with no substantive comments received. The FAA therefore 
finds that good cause exists for making these special conditions 
effective upon issuance. However, the FAA is requesting comments to 
allow interested persons to submit views that may not have been 
submitted in response to the prior opportunities for comment described 
above.

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 file in the docket all comments we receive, as well as a 
report summarizing each substantive public contact with FAA personnel 
about these 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 preamble 
between 7:30 a.m. and 4 p.m., Monday through Friday, except Federal 
holidays.
    We will consider all comments we receive by 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 these special 
conditions based on the comments we receive.
    If you want us to acknowledge receipt of your comments on these 
special conditions, include with your comments a self-addressed, 
stamped postcard on which you have written the docket number. We will 
stamp the date on the postcard and mail it back to you.

Background

    On February 14, 2007, API applied for a supplemental type 
certificate for winglets on the Dassault Falcon Model 900 and 900EX 
airplanes. These airplanes have Allied Signal engines, a maximum 
passenger capacity of 19, and a maximum takeoff weight of up to 49,000 
lbs.
    The Falcon 900 and 900EX airplanes, as modified by API, feature a 
wing-load-alleviation system that precludes deployment of the air 
brakes at certain airspeeds, thereby reducing wing loading. Special 
conditions have been applied on past airplane programs with similar 
wing-load-alleviation systems to require consideration of the effects 
of those systems on structures. For the Dassault 900 and 900EX models 
with winglets, failure of the wing-load-alleviation system can result 
in a FS below 1.5 as required by Sec.  25.303. Sections 25.303 and 
25.1309 do not take into account the effects of system failures on 
aircraft loads. A special condition is needed to account for these 
effects. These special conditions define the necessary requirements for 
assessing the effects of the air-brake wing-load-alleviation system on 
structures in the case of a system failure.

Type Certification Basis

    Under the provisions of 14 CFR 21.101, API must show that the 
Falcon 900 and 900EX airplanes, as changed, continue to meet the 
applicable provisions of the regulations incorporated by reference in 
Type Certificate No. A46EU or the applicable regulations in effect on 
the date of application for the change. The regulations incorporated by 
reference in the type certificate are commonly referred to as the 
``original type-certification basis.'' The regulations incorporated by 
reference in A46EU are as follows:
    14 CFR part 25 at Amendment 25-56 for the Falcon 900, at Amendment 
25-77 for the Falcon 900EX, and at other

[[Page 54924]]

amendment levels for various commercial designations. In addition, the 
certification basis includes certain special conditions, exemptions, 
equivalent levels of safety, and later or earlier amended sections of 
part 25 that are not relevant to these special conditions.
    In addition, if the regulations incorporated by reference do not 
provide adequate standards regarding the change, the applicant must 
comply with certain regulations in effect on the date of application 
for the change. The FAA has determined that the Falcon 900 and 900EX, 
as modified, must also comply with some sections of part 25, as amended 
by Amendment 25-119.
    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 Falcon 900 and 900EX airplanes 
because of a novel or unusual design feature, special conditions are 
prescribed under the provisions of 14 CFR 21.16.
    In addition to the applicable airworthiness regulations and special 
conditions, the Falcon 900 and 900EX airplanes 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 14 CFR 11.19, in 
accordance with Sec.  11.38, and they become part of the type-
certification basis under 14 CFR 21.101.
    Special conditions are initially applicable to the model for which 
they are issued. Should the applicant apply for a supplemental type 
certificate to modify any other model included on the same type 
certificate to incorporate the same novel or unusual design feature, 
the special conditions would also apply to the other model.

Novel or Unusual Design Features

    The Dassault Falcon Model 900 and 900EX airplanes, as modified by 
API, will incorporate the following novel or unusual design feature:
    The Airbrakes 2 inhibit system will be incorporated to retract, or 
prevent the deployment of, the Airbrakes 2 above 320 knots indicated 
airspeed (KIAS) to alleviate wing aerodynamic loading.

Applicability

    As discussed above, these special conditions are applicable to the 
Dassault Falcon Model 900 and 900EX airplanes as modified by API. 
Should API apply at a later date for a supplemental type certificate to 
modify any other model included on Type Certificate No. A16EU, to 
incorporate the same novel or unusual design feature, the special 
conditions would apply to that model as well.

Conclusion

    This action affects only one novel or unusual design feature on one 
model series of airplanes. It is not a rule of general applicability 
and affects only the applicant who applied to the FAA for approval of 
this feature 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 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 Falcon Model 900 and 900EX 
airplanes modified by Aviation Partners Incorporated.
    1. General. The following criteria will be used in determining the 
influence of a system and its failure conditions on the airplane 
structure.
    2. System fully operative. With the system fully operative, the 
following apply:
    a. Limit loads must be derived in all normal operating 
configurations of the system from all the limit conditions specified in 
part 25 subpart C (or defined by special condition or equivalent level 
of safety in lieu of those specified in part 25 subpart C), taking into 
account any special behavior of such a system or associated functions, 
or any effect on the structural performance of the airplane that may 
occur up to the limit loads. In particular, any significant 
nonlinearity (rate of displacement of control surface, thresholds, or 
any other system nonlinearities) must be accounted for in a realistic 
or conservative way when deriving limit loads from limit conditions.
    b. The airplane must meet the strength requirements of part 25 
(static strength, residual strength), using the specified factors to 
derive ultimate loads from the limit loads defined above. The effect of 
nonlinearities must be investigated beyond limit conditions to ensure 
that the behavior of the system presents no anomaly compared to the 
behavior below limit conditions. However, conditions beyond limit 
conditions need not be considered when it can be shown that the 
airplane has design features that do not allow it to exceed those limit 
conditions.
    c. The airplane must meet the aeroelastic stability requirements of 
Sec.  25.629.
    3. System in the failure condition. For any system-failure 
condition not shown to be extremely improbable, the following apply:
    a. At the time of occurrence. Starting from 1-g level-flight 
conditions, a realistic scenario, including pilot corrective actions, 
must be established to determine the loads occurring at the time of 
failure and immediately after failure.
    (i) For static-strength substantiation, these loads, multiplied by 
an appropriate FS that is related to the probability of occurrence of 
the failure, are ultimate loads to be considered for design. The FS is 
defined in Figure 1.

[[Page 54925]]

[GRAPHIC] [TIFF OMITTED] TR06SE11.015

    (ii) For residual-strength substantiation, the airplane must be 
able to withstand two-thirds of the ultimate loads defined in 
subparagraph 3(a)(i) of these special conditions. For pressurized 
cabins, these loads must be combined with the normal operating 
differential pressure.
    (iii) Freedom from aeroelastic instability must be shown up to the 
speeds defined in Sec.  25.629(b)(2). For failure conditions that 
result in speeds beyond design cruising speed/mach number 
(VC/MC), freedom from aeroelastic instability 
must be shown to increase speeds so that the margins intended by Sec.  
25.629(b)(2) are maintained.
    (iv) Failures of the system that result in forced-structural 
vibrations (oscillatory failures) must not produce loads that could 
result in detrimental deformation of primary structure.
    b. For the continuation of the flight. For the airplane in the 
system-failed state, and considering any appropriate reconfiguration 
and flight limitations, the following apply:
    (i) The loads derived from the following conditions (or defined by 
special condition or equivalent level of safety in lieu of the 
following conditions) at speeds up to VC/MC, or 
the speed limitation prescribed for the remainder of the flight, must 
be determined:
    (1) The limit-symmetrical-maneuvering conditions specified in 
Sec. Sec.  25.331 and 25.345.
    (2) The limit-gust-and-turbulence conditions specified in 
Sec. Sec.  25.341 and 25.345.
    (3) The limit-rolling conditions specified in Sec.  25.349.
    (4) The limit-unsymmetrical conditions specified in Sec. Sec.  
25.367 and 25.427(b) and (c).
    (5) The limit-yaw-maneuvering conditions specified in Sec.  25.351.
    (6) The limit-ground-loading conditions specified in Sec. Sec.  
25.473 and 25.491.
    (ii) For static-strength substantiation, each part of the structure 
must be able to withstand the loads in paragraph 3(b)(i) of these 
special conditions multiplied by a FS depending on the probability of 
being in this failure state. The FS is defined in Figure 2.
[GRAPHIC] [TIFF OMITTED] TR06SE11.016

Qj = (Tj)(Pj)

Where:

Tj = Average time spent in failure condition j (in hours)
Pj = Probability of occurrence of failure mode j (per hour)

    Note: If Pj is greater than 10-3 per flight hour, 
then a 1.5 FS must be applied to all limit-load conditions specified 
in part 25 subpart C.

    (iii) For residual-strength substantiation, the airplane must be 
able to withstand two-thirds of the ultimate loads defined in paragraph 
3(b)(ii) of these special condition. For pressurized cabins, these 
loads must be combined with the normal operating differential pressure. 
If the loads induced by the failure condition have a significant effect 
on fatigue or damage tolerance, then their effects must be taken into 
account.
    (iv) Freedom from aeroelastic instability must be shown up to a 
speed

[[Page 54926]]

determined from Figure 3. Flutter clearance speeds V' and V'' may be 
based on the speed limitation specified for the remainder of the flight 
using the margins defined by Sec.  25.629(b).
[GRAPHIC] [TIFF OMITTED] TR06SE11.017

    V' = Clearance speed as defined by Sec. 25.629(b)(2).
    V'' = Clearance speed as defined by Sec. 25.629(b)(1).
Qj = (Tj)(Pj)

Where:

Tj = Average time spent in failure condition j (in hours)
Pj = Probability of occurrence of failure mode j (per hour)

    Note: If Pj is greater than 10-\3\ per flight hour, 
then the flutter clearance speed must not be less than V''.

    (v) Freedom from aeroelastic instability must also be shown up to 
V' in Figure 3, above, for any probable system-failure condition 
combined with any damage required or selected for investigation by 
Sec.  25.571(b). Consideration of certain failure conditions may be 
required by other sections of part 25 regardless of calculated system 
reliability. Where analysis shows the probability of these failure 
conditions to be less than 10-\9\, criteria other than those 
specified in this paragraph may be used for structural substantiation 
to show continued safe flight and landing.
    4. Failure indications. For system-failure detection and 
indication, the following apply:
    a. The system must be checked for failure conditions, not extremely 
improbable, that degrade the structural capability below the level 
required by part 25 or that significantly reduce the reliability of the 
remaining system. As far as reasonably practicable, the flightcrew must 
be made aware of these failures before flight. Certain elements of the 
control system, such as mechanical and hydraulic components, may use 
special periodic inspections, and electronic components may use daily 
checks, in lieu of detection-and-indication systems to achieve the 
objective of this requirement. These certification-maintenance 
requirements must be limited to components that are not readily 
detectable by normal detection-and-indication systems and where service 
history shows that inspections provide an adequate level of safety.
    b. The existence of any failure condition, not extremely 
improbable, during flight that could significantly affect the 
structural capability of the airplane, and for which the associated 
reduction in airworthiness can be minimized by suitable flight 
limitations, must be signaled to the flightcrew. For example, failure 
conditions that result in an FS between the airplane strength and the 
loads of part 25 subpart C below 1.25, or flutter margins below V'', 
must be signaled to the flightcrew during flight.
    5. Dispatch with known failure conditions. If the airplane is to be 
dispatched in a known system-failure condition that affects structural 
performance, or affects the reliability of the remaining system to 
maintain structural performance, then the provisions of this special 
condition must be met, including the provisions of paragraph 2 in these 
special conditions for the dispatched condition, and paragraph 3 for 
subsequent failures. Expected operational limitations may be taken into 
account in establishing Pj as the probability of failure occurrence for 
determining the safety margin in Figure 1. Flight limitations and 
expected operational limitations may be taken into account in 
establishing Qj as the combined probability of being in the dispatched 
failure condition, and the subsequent failure condition for the safety 
margins in Figures 2 and 3. These limitations must be such that the 
probability of being in this combined failure state, and then 
subsequently encountering limit-load conditions, is extremely 
improbable. No reduction in these safety margins is allowed if the 
subsequent system-failure rate is greater than 1E-\3\ per 
hour.

    Issued in Renton, Washington, on August 29, 2011.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2011-22631 Filed 9-2-11; 8:45 am]
BILLING CODE 4910-13-P