[Federal Register Volume 67, Number 81 (Friday, April 26, 2002)]
[Rules and Regulations]
[Pages 20624-20625]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-10235]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM212; Special Conditions No. 25-02-04-SC]


Special Conditions: Airbus, Model A340-500 and -600 Airplanes; 
Sudden Engine Stoppage

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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SUMMARY: These special conditions are issued for Airbus Model A340-500 
and -600 airplanes. These airplanes will have a novel or unusual design 
feature when compared to the state of technology envisioned in the 
airworthiness standards for transport category airplanes, associated 
with engine size and torque load, which affects sudden engine stoppage. 
The applicable airworthiness regulations do not contain adequate or 
appropriate safety standards for this design feature. 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 17, 2002.

FOR FURTHER INFORMATION CONTACT: Tim Backman, FAA, ANM-116, Transport 
Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue 
SW., Renton, Washington, 98055-4056; telephone (425) 227-2797; 
facsimile (425) 227-1149.

SUPPLEMENTARY INFORMATION:

Background

    On November 14, 1996, Airbus applied for an amendment to U.S. type 
certificate (TC) A43NM to include the new Models A340-500 and -600. 
These models are derivatives of the A340-300 airplane, which is 
approved under the same TC.
    The Model A340-500 fuselage is a 6-frame stretch of the Model A340-
300 and is powered by 4 Rolls Royce Trent 553 engines, each rated at 
53,000 pounds of thrust. The airplane has interior seating arrangements 
for up to 375 passengers, with a maximum takeoff weight (MTOW) of 
820,000 pounds. The Model 340-500 is intended for long-range operations 
and has additional fuel capacity over that of the model A340-600.
    The Model A340-600 fuselage is a 20-frame stretch of the Model 
A340-300 and is powered by 4 Rolls Royce Trent 556 engines, each rated 
at 56,000 pounds of thrust. The airplane has interior seating 
arrangements for up to 440 passengers, with a MTOW of 804,500 pounds.

Type Certification Basis

    Under the provisions of 14 CFR 21.101, Airbus must show that the 
Model A340-500 and -600 airplanes meet the applicable provisions of the 
regulations incorporated by reference in TC A43NM or the applicable 
regulations in effect on the date of application for the change to the 
type certificate. 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 TC 
A43NM are 14 CFR part 25 effective February 1, 1965, including 
Amendments 25-1 through 25-63 and Amendments 25-64, 25-65, 25-66, and 
25-77, with certain exceptions that are not relevant to these special 
conditions.
    In addition, if the regulations incorporated by reference do not 
provide adequate standards with respect to 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 Model A340-
500 and -600 airplanes must be shown to comply with 14 CFR 25-1 through 
25-91, with certain FAA-allowed reversions for specific part 25 
regulations to the part 25 amendment levels of the original type 
certification basis.
    Airbus has also chosen to comply with part 25 as amended by 
Amendments 25-92, -93, -94, -95, -97, -98, and -104.
    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 Airbus Model A340-500 and -600 
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 Airbus Model A340-500 and -600 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.
    Special conditions, as defined in 14 CFR 11.19, are issued in 
accordance with Sec. 11.38 and become part of the type certification 
basis in accordance with 14 CFR 21.101(b)(2).
    Special conditions are initially applicable to the model for which 
they are issued. Should the type certificate

[[Page 20625]]

for that model be amended later to include any other model that 
incorporates the same novel or unusual design feature, or should any 
other model already included on the same type certificate be modified 
to incorporate the same novel or unusual design feature, the special 
conditions would also apply to the other model under the provisions of 
14 CFR 21.101(a)(1).

Novel or Unusual Design Features

    The Airbus Model A340-500 and A340-600 airplanes will incorporate 
novel or unusual design features involving engine size and torque load 
that affect sudden engine stoppage conditions. Airbus proposes to treat 
the sudden engine stoppage condition resulting from structural failure 
as an ultimate load condition. Section 25.361(b)(1) of part 25 
specifically defines the seizure torque load resulting from structural 
failure as a limit load condition.

Discussion

    The limit engine torque load imposed by sudden engine stoppage due 
to malfunction or structural failure (such as compressor jamming) has 
been a specific requirement for transport category airplanes since 
1957. The size, configuration, and failure modes of jet engines have 
changed considerably from those envisioned when the engine seizure 
requirement of Sec. 25.361(b) was first adopted. Current engines are 
much larger and are now designed with large bypass fans capable of 
producing much larger torque loads if they become jammed. It is evident 
from service history that the frequency of occurrence of the most 
severe sudden engine stoppage events are rare.
    Relative to the engine configurations that existed when the rule 
was developed in 1957, the present generation of engines are 
sufficiently different and novel to justify issuance of special 
conditions to establish appropriate design standards. The latest 
generation of jet engines are capable of producing, during failure, 
transient loads that are significantly higher and more complex than the 
generation of engines that were present when the existing standard was 
developed. Therefore, the FAA has determined that special conditions 
are needed for the Model A340-500 and -600 airplanes.
    In order to maintain the level of safety envisioned in 
Sec. 25.361(b), a more comprehensive criteria is needed for the new 
generation of high bypass engines. These special conditions would 
distinguish between the more common seizure events and those rarer 
seizure events resulting from structural failures. For those rarer but 
severe seizure events, these criteria could allow some deformation in 
the engine supporting structure (ultimate load design) in order to 
absorb the higher energy associated with the high bypass engines, while 
at the same time protecting the adjacent primary structure in the wing 
and fuselage by providing a higher safety factor. The criteria for the 
more severe events would no longer be a pure static torque load 
condition, but would account for the full spectrum of transient dynamic 
loads developed from the engine failure condition.

Publication of Notice of Proposed Special Conditions

    Notice of proposed special conditions No. NM-02-04-SC for Airbus 
Model A340-500 and -600 airplanes was published in the Federal Register 
on February 25, 2002 (67 FR 8487). No comments were received, and the 
special conditions are adopted as proposed.

Applicability

    These special conditions are applicable to the Airbus Model A340-
500 and -600 airplanes. Should Airbus apply at a later date for a 
change to the type certificate to include another model incorporating 
the same novel or unusual design feature, the special conditions would 
apply to that model as well under the provisions of Sec. 21.101(a)(1).

Conclusion

    This action affects certain novel or unusual design features on the 
Model A340-500 and A340-600 airplanes. It is not a rule of general 
applicability, and it affects only the applicant who 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 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 Airbus Model A340-500 and -600 
airplanes.
    The following special conditions are issued in lieu of compliance 
with 14 CFR 25.361(b) and in lieu of the previously issued special 
conditions, ``Limit Engine Torque,'' recorded as item 9 of Special 
Conditions No. 25-ANM-69 (Docket No. NM-75), Airbus Model A340 Series 
Airplanes.
    1. Sudden Engine Stoppage.
    (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.
    (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.
    (2) The maximum acceleration of the auxiliary power unit.
    (c) For engine supporting structure, an ultimate loading condition 
must be considered that combines 1g flight loads with the transient 
dynamic loads resulting from each of the following:
    (1) The loss of any fan, compressor, or turbine blade.
    (2) Where applicable to a specific engine design, and separately 
from the conditions specified in paragraph 1(c)(1), any other engine 
structural failure that results in higher loads.
    (d) The ultimate loads developed from the conditions specified in 
paragraphs 1(c)(1) and 1(c)(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.

    Issued in Renton, Washington, on April 17, 2002.
Lirio Liu-Nelson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 02-10235 Filed 4-25-02; 8:45 am]
BILLING CODE 4910-13-P