Special Conditions: General Electric Aircraft Engines Models CT7- 6D, CT7-6E and CT7-8 Turboshaft Engines.

[Federal Register Volume 64, Number 103 (Friday, May 28, 1999)]
[Rules and Regulations]
[Pages 28900-28901]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-13637]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 33

[Docket No. NE121; Special Conditions No. 33-002-SC]


Special Conditions: General Electric Aircraft Engines Models CT7-
6D, CT7-6E and CT7-8 Turboshaft Engines.

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 General Electric 
Aircraft Engines (GEAE) Models CT7-6D, CT7-6E and CT7-8 turboshaft 
engines. These engines will have 30-second one-engine-inoperative (OEI) 
and 2-minute OEI ratings. The applicable airworthiness standards do not 
contain appropriate safety standards for engine overspeed test 
requirements for these engine ratings. This document contains the 
additional safety standards for the overspeed test for these ratings 
under Sec. 33.27 that the Administrator considers necessary to 
establish a level of safety equivalent to that established by the 
existing airworthiness standards. This document also specifies the 
mandatory post-flight engine inspection and maintenance requirements 
for these ratings in accordance with Sec. 33.4.

DATES: The effective date of these special conditions is May 21, 1999. 
Comments must be received on or before July 27, 1999.

ADDRESSES: Comments on these special conditions may be mailed in 
duplicate to: Federal Aviation Administration, Office of the Regional 
Counsel, Attention: Docket NE121; 12 New England Executive Park, 
Burlington, Massachusetts 01803-5299, or delivered in duplicate to the 
Office of the Regional Counsel at the above address. Comments must be 
marked: Docket No. NE121. Comments may be inspected in the Docket 
weekdays, except Federal holidays, between 8:00 a.m. and 4:30 p.m.

FOR FURTHER INFORMATION CONTACT: Chung Hsieh, FAA, Engine and Propeller 
Standards Staff, ANE-110, Engine and Propeller Directorate, Aircraft 
Certification Service, 12 New England Executive Park, Burlington, 
Massachusetts 01803-5299; telephone (781) 238-7115; facsimile (781) 
238-7199.

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA has determined that good cause exists for making these 
special conditions effective upon issuance; however, interested persons 
are invited to submit such written data, views, or arguments as they 
may desire. Communications should identify the docket and special 
conditions numbers and be submitted in duplicate to the address 
specified above. All communications received on or before the closing 
date for comments will be considered by the Administrator. These 
special conditions may be changed in light of the comments received. 
All comments submitted will be available in the 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 rulemaking will be filed in the docket. 
Persons wishing the FAA to acknowledge receipt of their comments 
submitted in response to this request must submit with those comments a 
self-addressed, stamped postcard on which the following statement is 
made: ``Comments to Docket No. NE121.'' The postcard will be date-
stamped and returned to the commenter.

Background

    On May 24, 1996, GEAE applied for an amendment to type certificate 
E8NE to include a new model CT7-6E turboshaft engine. On July 15, 1996, 
GEAE applied for an amendment to type certificate E8NE to include a new 
model CT7-6D turboshaft engine. On August 12, 1996, GEAE applied for an 
amendment to type certificate E8NE to include a new model CT7-8 
turboshaft engine. These models are all derivatives of the CT7 series 
turboshaft engine. With all of these applications GEAE applied for 30-
second OEI and 2-minute OEI ratings for the new engine designs. The 
CT7-6D and the CT7-6E turboshaft engines will be rated at 30-second 
OEI, 2-minute OEI, continuous OEI, takeoff, and maximum continuous 
ratings. The CT7-8 turboshaft engine will be rated at 30-second OEI, 2-
minute OEI, 30-minute OEI, takeoff, and maximum continuous ratings.
    On June 19, 1996, the FAA published a final rule setting 
airworthiness standards for 30-second and 2-minute OEI engine ratings 
(61 FR 31324). Prior to that rule the airworthiness standards for 
engines, 14 CFR part 33, did not contain appropriate safety standards 
for engine overspeed test requirements for 30-second and 2-minute OEI 
engine ratings. Engine manufacturers who had applied for type 
certificates for engine designs that contained 30-second and 2-minute 
OEI ratings were issued special conditions to address, among other 
things, engine overspeed test requirements for those ratings, which 
were considered at the time to be novel and unusual engine ratings. The 
final rule, however, did not contain the proposed revisions to the 
airworthiness standards on engine overspeed test for these OEI ratings 
under Sec. 33.27 that appeared in both the Notice of Proposed 
Rulemaking (NPRM) No. 89-27, published on September 22, 1989 (54 FR 
39080), and the Supplemental Notice of Proposed Rulemaking (SNPRM) No. 
89-27A (60 FR 7380), published on February 7, 1995. The FAA elected to 
drop the proposed changes to Sec. 33.27 from the final rule in response 
to commenters who noted that the proposed revisions were not consistent 
with the status of the discussions on OEI test requirements ongoing at 
the time by a working group of the Aviation Rulemaking Advisory 
Committee

[[Page 28901]]

(ARAC). The FAA agreed that the proposed changes to Sec. 33.27 were not 
completely harmonized with the proposed equivalent rules in the Joint 
Airworthiness Requirements--Engine (JAR-E) published by the European 
Joint Aviation Authority (JAA). The preamble to the final rule states 
that until the ARAC completes its work to harmonize Sec. 33.27 with the 
equivalent rule in the JAR-E, the FAA should address engine overspeed 
test requirements for 30-second and 2-minute OEI engine ratings on a 
case by case basis. These special conditions reflect that policy and 
allow this applicant to proceed with the certification of these engine 
designs on the same basis as previous applicants seeking approval for 
30-second and 2-minute OEI engine ratings.

Type Certification Basis

    Under the provisions of 14 CFR 21.101, GEAE must show that GEAE 
models CT7-6D, CT7-6E and CT7-8 turboshaft engines meet the applicable 
provisions of the regulations incorporated by reference in Type 
Certificate No. E8NE 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 original type certification 
basis for the CT7-6D engine is 14 CFR part 33, effective February 1, 
1965, as amended by Amendments 33-1 through 33-5. The original type 
certification basis for the CT7-6E engine is 14 CFR part 33, effective 
February 1, 1965, as amended by Amendments 33-1 through 33-16. The 
original type certification basis for the CT7-8 engine is 14 CFR part 
33, effective February 1, 1965, as amended by Amendments 33-1 through 
33-17.
    If the Administrator finds that the applicable airworthiness 
regulations (i.e., 14 CFR part 33) do not contain appropriate safety 
standards for the GEAE CT7-6D, CT7-6E and CT7-8 engines because of the 
30-second OEI and 2-minute OEI engine ratings, special conditions are 
prescribed under the provisions of 14 CFR 21.16.
    Special conditions, as appropriate, are issued in accordance with 
14 CFR 11.49, as required by 14 CFR 11.28 and 11.29(b), and become part 
of the type certification basis in accordance with 14 CFR 21.101(b)(2).
    Special conditions are 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 engine ratings, or 
should any other model already included on the same type certificate be 
modified to incorporate the same engine ratings, the special conditions 
would also apply to the other model under the provisions of 14 CFR 
21.101(a)(1).

Applicability

    As discussed above, these special conditions are applicable to the 
GEAE CT7-6D, CT7-6E and CT7-8 turboshaft engines. Should GEAE apply at 
a later date for a change to the type certificate to include another 
model incorporating the same engine ratings, the special conditions 
would apply to that model as well under the provisions of 14 CFR 
21.101(a)(1).

Conclusion

    This action affects only certain engine ratings for the GEAE CT7-
6D, CT7-6E and CT7-8 turboshaft engines. It is not a rule of general 
applicability, and it affects only the applicant who applied to the FAA 
for approval of these ratings.

List of Subjects in 14 CFR Part 33

    Air transportation, Aircraft, Aviation safety, Safety.

    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 the GEAE Models CT7-6D, CT7-6E and 
CT7-8 turboshaft engines.

Section 33.4, Instructions for Continued Airworthiness.

    In addition to the requirements of Sec. 33.4, the mandatory 
inspection and maintenance actions required following the use of the 
30-second or 2-minute OEI rating must be included in the 
airworthiness limitations section of the appropriate engine manuals.

Section 33.27, Turbine, Compressor, Fan, and Turbo-supercharger 
Rotors.

    For engines having 30-second and 2-minute OEI ratings, in 
addition to the requirements of Sec. 33.27(b), turbine and 
compressor rotors must have sufficient strength to withstand the 
conditions specified in one of the following tests for the most 
critically stressed rotor component of each turbine and compressor 
including integral drum rotors and centrifugal compressor, as 
determined by analysis or other acceptable means. The selection of 
the test from the following paragraph (a) or (b) of this section is 
determined by the speed defined in paragraph (a)(2) or (b)(2), 
whichever is higher.
    (a) Test for a period of two and one-half minutes-
    (1) At its maximum operating temperature except as provided in 
Sec. 33.27(c)(2)(iv); and
    (2) At the highest speed determined, in accordance with 
Sec. 33.27(c)(2)(i) through (iv).
    (3) This test may be performed using a separate test vehicle as 
desired.
    (b) Test for a period of 5 minutes-
    (1) At its maximum operating temperature except as provided in 
Sec. 33.27(c)(2)(iv); and
    (2) At 100 percent of the highest speed that would result from 
failure of the most critical component of each turbine and 
compressor or system in a representative installation of the engine 
when operating at 30-second and 2-minute OEI rating conditions; and
    (3) The test speed must take into account minimum material 
properties, maximum operating temperature, and the most adverse 
dimensional tolerances.
    (4) This test may be performed using a separate test vehicle as 
desired. Following the test, rotor growth and distress beyond 
dimensional limits for an overspeed condition is permitted for 30-
second and 2-minute OEI ratings only, provided the structural 
integrity of the rotor is maintained, as shown by a procedure 
acceptable to the Administrator.

    Issued in Burlington, Massachusetts, on May 21, 1999.
David A. Downey,
Assistant Manager, Engine and Propeller Directorate, Aircraft 
Certification Service.
[FR Doc. 99-13637 Filed 5-27-99; 8:45 am]
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