[Federal Register Volume 59, Number 4 (Thursday, January 6, 1994)]
[Proposed Rules]
[Pages 703-704]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-136]


[[Page Unknown]]

[Federal Register: January 6, 1994]


                                                     VOL. 59, NO. 4

                                          Thursday, January 6, 1994
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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 33

[Docket No. 93-ANE-66; Notice No. 33-ANE-05]

 

Special Conditions; Pratt & Whitney Model(s) PW4073 and PW4084 
Turbofan Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed special conditions.

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SUMMARY: This notice proposes special conditions for the Pratt & 
Whitney (PW) Model(s) PW4073 and PW4048 turbofan engines. The 
applicable regulations do not contain adequate or appropriate safety 
standards for the protection of these systems from medium and large 
bird ingestion. This notice proposes the additional safety standards 
which the Administrator considers necessary to establish a level of 
safety equivalent to that established by the airworthiness standards 
for aircraft engines of the Federal Aviation Regulations (FAR).

DATES: Comments must be submitted on or before February 22, 1994.

ADDRESSES: Comments on this proposal may be submitted in triplicate to: 
Federal Aviation Administration (FAA), New England Region, Office of 
the Assistant Chief Counsel, Attn: Rules Docket No. 93-ANE-66, 12 New 
England Executive Park, Burlington, Massachusetts 01803-5299. Comments 
must be marked: Docket No. 93-ANE-66. Comments may be inspected at this 
location between 8 a.m. and 4:30 p.m., Monday through Friday, except 
Federal holidays.

FOR FURTHER INFORMATION CONTACT:
John Golinski, Engine and Propeller Standards Staff, ANE-110, Engine 
and Propeller Directorate, Aircraft Certificate Service, FAA, New 
England Region, 12 New England Executive Park, Burlington, 
Massachusetts 01803-5229; telephone (617) 238-7119; fax (617) 238-7199.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed special conditions by submitting such written data, views, or 
arguments as they may desire. Communications should identify the Rules 
Docket number and be submitted in triplicate to the address specified 
under ``ADDRESSES.'' All communications received on or before the 
closing date for comments, specified under ``DATES,'' will be 
considered by the Administrator before taking action on the proposal. 
The proposal contained in this notice may be changed in light of the 
comments received.
    Comments are specifically invited on the overall regulatory, 
economic environmental, and energy aspects of the proposed special 
conditions. All comment submitted will be available in the Rules Docket 
for examination by interested persons, both before and after the 
closing date for comments. A report summarizing each substantive public 
contact with FAA personnel concerning this proposal will be filed in 
the docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit with those comments a 
self-addressed, stamped postcard on which the following statement is 
made: ``Comments to Docket No. 93-ANE-66.'' The postcard will be date 
stamped and returned to the commenter.

Background

    On December 10, 1990, Pratt & Whitney applied for type 
certification of PW Model(s) PW4073 and PW4084 turbofan engines. The 
FAA has determined that the current foreign object ingestion 
requirements of Sec. 33.77(a) for four pound birds; and Sec. 33.77(b) 
for one and one-half pound flocking birds, do not adequately represent 
the bird threat encountered in service. A study of in-service bird 
ingestion events has indicated a need to modify the bird ingestion 
requirements of this section to ensure design integrity and demonstrate 
an adequate level of safety.
    The FAA has concluded that additional safety standards must be 
applied to Pratt & Whitney Model(s) PW4073 and PW4048 turbofan engines 
to demonstrate that they are capable of acceptable operation after 
medium and large bird ingestion. The applicable airworthiness 
requirements do not contain adequate or appropriate safety standards 
for type certification with respect to the new design criteria. This 
new design criteria assumes the actual bird threat encountered in 
service.

Type of Certification Basis

    Under the provisions of Sec. 21.101 of the FAR, Pratt & Whitney 
must show that the PW Model(s) PW4073 and PW4084 turbofan engines meet 
the requirements of the applicable regulations in effect on the date of 
the application. Those Federal Aviation Regulations are Sec. 21.21 and 
part 33, effective February 1, 1965, as amended through August 10, 
1990, Amendment 33-14.
    The Administrator finds that the applicable airworthiness 
regulations in part 33, as amended, do not contain adequate or 
appropriate safety standards for the PW Model(s) PW4073 and PW4084 
turbofan engines because of its unique design criteria. Therefore, the 
Administrator proposes these special conditions under the provisions of 
Sec. 21.16 to establish a level of safety equivalent to that 
established in the regulations.
    Special conditions, as appropriate, are issued in accordance with 
Sec. 11.49 of the FAR after public notice and opportunity for comment, 
as required by Secs. 11.28 and 11.29(b), and become part of the type 
certification basis in accordance with Sec. 21.101(b)(2).

Conclusion

    This action affects only PW Model(s) PW4073 and PW4048 turbofan 
engines. It is not a rule of general applicability and affects only the 
manufacturer who applied to the FAA for approval of these new design 
criteria on the engine.

List of Subjects in 14 CFR Part 33

    Air transportation, Aircraft, Aviation safety, Safety.
    The authority citation for these special conditions continues to 
read as follows:

    Authority: 49 U.S.C. App. 1354(a), 1421, 1423; 49 U.S.C. 106(g); 
14 CFR 21.16, and 14 CFR 11.28.

The Proposed Special Conditions

    Accordingly, the Federal Aviation Administration (FAA) proposes the 
following special conditions as part of the type certification basis 
for the Pratt & Whitney Model(s) PW4073 and PW4084 turbofan engines.
    In lieu of the requirements of FAR Sec. 33.77(a) and (b), the 
following tests and analyses must be conducted, unless compliance can 
be shown by alternate methods acceptable to the Administrator:
    (a) It must be shown that the ingestion of a single large bird, 
under the conditions prescribed in Appendix A, will not cause the 
engine to:
    (1) catch fire;
    (2) release hazardous fragments through the engine casing;
    (3) generate loads greater than those ultimate loads specified 
under Sec. 33.23(a);
    (4) lose the ability to be shut down; or
    (5) generate other conditions hazardous to the aircraft.
    (b) Alternatively, if compliance with the bird ingestion 
requirements of paragraph (a) of this special condition is not 
established, the applicant must demonstrate that compliance with the 
containment requirements of Sec. 33.94(a) constitutes a more severe 
demonstration than the requirements of paragraph (a) of this special 
condition. The engine type certification documentation will then be 
endorsed to reflect this alternative compliance method.
    (c) It must be shown that the ingestion of medium birds, under the 
conditions prescribed in Appendix B, will not cause the engine to:
    (1) Sustain more than a 25 percent thrust loss;
    (2) Be shut down during the required run-on demonstration 
prescribed in Appendix B;
    (3) Exceed any engine operating limitations to the extent that the 
engine cannot comply with this section; or
    (4) Generate other conditions hazardous to the aircraft.
    (d) It must be shown that engine spinner impact by one large bird 
and by the single largest medium bird, under the respective conditions 
prescribed in Appendices A and B, will not affect the engine to the 
extent that it cannot comply with the requirements of paragraphs (a) 
and (b of this special condition.

Appendix A--Large Bird Ingestion Test Procedures

    (a) The test shall be conducted with the engine stabilized at 
rated takeoff thrust for the test day ambient conditions prior to 
the ingestion.
    (b) The test shall be conducted using one eight-pound bird 
targeted at the the most critical location and ingested at a bird 
speed of 200 knots.
    (c) Power lever movement is not permitted within 15 seconds 
following the ingestion event.

Appendix B--Medium Bird Ingestion Test Procedures

    (a) The ingestion test shall be conducted with the engine 
stabilized at rated takeoff thrust for the test day ambient 
conditions prior to the ingestion.
    (b) The test shall be conducted to simulate a flock encounter, 
with all birds ingested within approximately one second, and using 
the more severe of the following bird weight/quantity combinations:
    (1) Six 1.5-pound and one 2.5-pound birds.
    (2) Four 2.5-pound birds.
    (c) Bird targeting shall be one 2.5-pound bird at the core 
primary flow path, and the remaining birds targeted at critical fan 
rotor locations.
    (d) Bird ingestion velocity shall be the most critical velocity 
between V1 minimum through 250 knots.
    (e) Power lever movements between stages must occur in 10 
seconds or less. The following test schedule will be used as the 
post-ingestion run-on demonstration:
    (1) Two minutes with no power lever movement.
    (2) Three minutes at 75 percent of takeoff thrust.
    (3) Six minutes at 75 percent of maximum continuous thrust.
    (4) Six minutes at 50 percent of maximum continuous thrust.
    (5) One minute at approach idle.
    (6) Two minutes at 75 percent of takeoff thrust.
    (7) Retard throttle to idle.
    (8) Shut down the engine.
    (f) An analysis or component/engine test(s) acceptable to the 
Administrator shall be conducted to determine the critical ingestion 
parameters for medium bird ingestion that relates to airspeeds from 
V1 minimum through 250 knots. The analysis or test(s) must also show 
satisfactory engine operation for medium bird ingestion at the most 
severe ambient operating condition approved for the engine that may 
be experienced in service.

    Issued in Burlington, Massachusetts, on December 21, 1993.
Jay J. Pardee,
Acting Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 94-136 Filed 1-5-94; 8:45 am]
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