[Federal Register Volume 67, Number 37 (Monday, February 25, 2002)]
[Proposed Rules]
[Pages 8487-8489]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-4410]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

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


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

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special conditions.

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SUMMARY: This notice proposes special conditions for Airbus Industries 
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 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.

EFFECTIVE DATE: Comments must be received on or before March 27, 2002.

ADDRESSES: Comments on this proposal may be mailed in duplicate to: 
Federal Aviation Administration, Transport Airplane Directorate, Attn: 
Rules Docket (ANM-113), Docket No. NM212, 1601 Lind Avenue SW., Renton, 
Washington, 98055-4056; or delivered in duplicate to the Transport 
Airplane Directorate at the above address. All comments must be marked: 
Docket No. NM212. Comments may be inspected in the Rules Docket 
weekdays, except Federal holidays, between 7:30 a.m. and 4:00 p.m.

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:   

Comments Invited

    The FAA invites interested persons to participate in this 
rulemaking by submitting written comments, data, or views. The most 
helpful comments reference a specific portion of the proposal, 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. The docket is available 
for public inspection before and after the comments 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 4:00 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 expenses or delay. We may change 
this proposal for 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 November 14, 1996, Airbus Industries 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

[[Page 8488]]

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 Roll Royce Trend 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 Certificate Basis

    Under the provisions of 14 CFR Sec. 21.101, Airbus Industrie 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 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 proposed 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 Industrie 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 Industrie 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 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 Industrie 
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 torgue 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. The proposed special conditions 
would distinguish between the more common seizure events and those 
rarer seizure events resulting from structural failures. For these 
rarer but severe seizure events, the proposed 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.

Applicability

    These special conditions are applicable to the Airbus Model A340-
500 and -600 ailplanes. Should Airbus Industries 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 Proposed Special Conditions

    Accordingly, The Federal Aviation Administration (FAA) proposes the 
following special conditions as part of the type certification basis 
for Airbus Industrie Model A340-500 and -600 airplanes.
    The following special conditions are proposed in lieu of compliance 
with 14

[[Page 8489]]

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 industrie 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 imposing by each of the following:
    (1) Sudden auxiliary power unit deceleration due to malfunction or 
structural failure.
    (2) The maxium 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 (c)(1) and (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 February 13, 2002.
Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 02-4410 Filed 2-22-02; 8:45 am]
BILLING CODE 4910-13-M