Document ID: FAA-2011-1137-0002
Agency: faa
Document Type: Notice
Title: Special Conditions: Gulfstream Aerospace LP (GALP) Model G280 airplane, Limit Engine Torque Loads for Sudden Engine Stoppage
Posted Date: 2011-10-14T04:00Z

[Federal Register Volume 76, Number 199 (Friday, October 14, 2011)]
[Rules and Regulations]
[Pages 63822-63823]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-26557]

[[Page 63822]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2011-1107; Special Conditions No. 25-447-SC]

Special Conditions: Gulfstream Aerospace LP (GALP) Model G280 
Airplane, Limit Engine Torque Loads for Sudden Engine Stoppage

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 Gulfstream 
Aerospace LP (GALP) model G280 airplane. This airplane will have a 
novel or unusual design feature associated with engine torque loads 
imposed by 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.

DATES: The effective date of these special conditions is October 6, 
2011. We must receive your comments by November 28, 2011.

ADDRESSES: You must mail two copies of your comments to: Federal 
Aviation Administration, Transport Airplane Directorate, Attn: Rules 
Docket (ANM-113), Docket No. FAA-2011-1107, 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. FAA-2011-1107. 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: Carl Niedermeyer, Transport Airplane 
Directorate, Aircraft Certification Service, 1601 Lind Avenue, SW., 
Renton, Washington 98057-3356; telephone (425) 227-2279; facsimile 
(425) 227-1149.

SUPPLEMENTARY INFORMATION: The FAA has determined that notice of, and 
opportunity for prior public comment on, these special conditions are 
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 prior instances 
with no substantive comments received. The FAA therefore finds that 
good cause exists for making these special conditions effective upon 
issuance.

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 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 March 30, 2006, GALP applied for a type certificate for their 
new Model G280 airplane. The G280 is an 8- to 10-passenger (19 
maximum), twin-engine airplane with a 41,000-foot cruise altitude, 
maximum operating altitude of 45,000 feet, and a range of approximately 
3,400 nautical miles.

Type Certification Basis

    Under the provisions of 14 CFR 21.17, GALP must show that the Model 
G280 airplane meets the applicable provisions of part 25 as amended by 
Amendments 25-1 through 25-117.
    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 Model G280 airplane because of a 
novel or unusual design feature, special conditions are prescribed 
under the provisions of Sec.  21.16.
    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.
    In addition to the applicable airworthiness regulations and special 
conditions, the Model G280 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; and the FAA must issue a 
finding of regulatory adequacy under Sec.  611 of Public Law 92-574, 
the ``Noise Control Act of 1972.''
    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 Sec.  21.17(a)(2).

Novel or Unusual Design Features

    The GALP Model G280 airplane incorporates a novel or unusual design 
feature involving engine size and related torque load that affect 
sudden engine-stoppage conditions.

Discussion

    The size, configuration, and failure modes of jet engines have 
changed considerably from those envisioned by 14 CFR 25.361(b), when 
the engine-seizure requirement was first adopted. Engines have become 
larger and are now designed with large bypass fans capable of producing 
much larger and more complex dynamic loads. Relative to the engine 
configurations that existed when the rule was developed in 1957, the 
present generation of engines is sufficiently different and novel to 
justify issuance of a special condition to establish appropriate design 
standards for the GALP Model G280 airplane type design.
    Consideration of 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. In the past, the design torque loads 
associated with typical failure scenarios have been estimated by the 
engine manufacturer and were provided to the airframe manufacturer as 
limit loads. These limit loads were considered simple and pure torque 
static loads.
    It is evident from service history that the engine-failure events 
that tend to cause the most severe loads are fan-blade failures, which 
occur much less frequently than the typical ``limit'' load condition.
    The regulatory authorities and industry have developed a 
standardized requirement in the Aviation Rulemaking Advisory Committee 
(ARAC) forum.

[[Page 63823]]

The technical aspects of this requirement have been agreed upon and 
have been accepted by the ARAC Loads and Dynamics Harmonization Working 
Group, and incorporated in EASA CS-25. The proposed special conditions 
outlined below reflect the ARAC recommendation and CS-25. In addition, 
the ARAC recommendation includes corresponding advisory material that 
is considered an acceptable means of compliance to the proposed special 
conditions outlined below.
    To maintain the level of safety envisioned by Sec.  25.361(b), more 
comprehensive criteria are needed for the new generation of high-bypass 
engines. These proposed special conditions would distinguish between 
the more-common engine-failure events and those rare events resulting 
from structural failures. The more-common events would continue to be 
treated as static torque limit load conditions. The more-severe events 
resulting from extreme engine-failure conditions (such as loss of a 
full fan blade at redline speed), would be treated as full dynamic-load 
conditions. These would be considered ultimate loads, and include all 
transient loads associated with the event. An additional safety factor 
would be applied to the more-critical airframe supporting structure.

Applicability

    As discussed above, these special conditions are applicable to the 
GALP Model G280 airplane. Should GALP 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.

Conclusion

    This action affects only certain novel or unusual design features 
on one model of airplane. It is not a rule of general applicability.
    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 GALP Model 
G280 airplane is imminent, the FAA finds that good cause exists to make 
these special conditions effective upon issuance.

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 GALP Model G280 airplane.
    In lieu of 14 CFR 25.361(b), the following special conditions are 
proposed:
    1. 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:
    (a) Sudden engine deceleration due to a malfunction, which could 
result in a temporary loss of power or thrust; and
    (b) the maximum acceleration of the engine.
    2. For auxiliary power unit (APU) installations, the APU 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:
    (a) Sudden APU deceleration due to malfunction or structural 
failure; and
    (b) The maximum acceleration of the APU.
    3. For engine-supporting structure, an ultimate loading condition 
must be considered that combines 1g flight loads with the transient 
dynamic loads resulting from:
    (a) The loss of any fan, compressor, or turbine blade; and 
separately
    (b) Where applicable to a specific engine design, any other engine 
structural failure that results in higher loads.
    4. The ultimate loads developed from the conditions specified in 
paragraphs 3(a) and 3(b) of these special conditions 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.
    5. Any permanent deformation that results from the conditions 
specified in paragraph 3 of these special conditions must not prevent 
continued safe flight and landing.

    Issued in Renton, Washington, on October 6, 2011.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2011-26557 Filed 10-13-11; 8:45 am]
BILLING CODE 4910-13-P