AD 96-26-01

This amendment adopts a new airworthiness directive (AD), applicable to General Electric Aircraft Engines (GE) CT7 series turboprop engines, that requires replacement of the gas generator turbine stage 2 forward cooling plates prior to the published cyclic life limits. The AD also defines the new, reduced cyclic life limits for the affected forward cooling plates. This amendment is prompted by reports of gas generator turbine stage 2 forward cooling plate failures. The actions specified by this AD are intended to prevent gas generator turbine stage 2 forward cooling plate failure, which could result in an uncontained engine failure.

Final rule.

96-26-01 General Electric Aircraft Engines: Amendment 39-9864. Docket 96-ANE-06.
Applicability: General Electric Aircraft Engines (GE) Models CT7-5A2, -7A, -9B, and -9C turboprop engines, with gas generator turbine (GGT) stage 2 forward cooling plates, Part Number (P/N) 6064T10P01 and P/N 5086T91P02, installed. These engines are installed on but not limited to Construcciones Aeronauticas, SA (CASA) CN-235 series and SAAB-SCANIA SF340 series aircraft.
Note 1: This airworthiness directive (AD) applies to each engine identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For engines that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (c) of this AD. The request should include an assessment ofthe effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.
Compliance: Required as indicated, unless accomplished previously.
To prevent GGT stage 2 forward cooling plate failure, which could result in an uncontained engine failure, accomplish the following:
(a) Within 30 days after the effective date of this AD, or prior to reaching the new, reduced cyclic life limits listed in the Accomplishment Instructions of GE Aircraft Engines (CT7-TP Series) Service Bulletin (SB) A72-381, dated January 17, 1996, whichever occurs later, remove from service GGT stage 2 forward cooling plates, and replace with a serviceable part, which is defined as a GGT stage 2 forward cooling plate that has less than the new, reduced cyclic limits on the effective date of this AD, as defined in that SB.
(b) This action establishes the following new, reduced cyclic life limits for affected GGT stage 2 forward cooling plates:
(1) 8,000 cycles since new (CSN) for GGT stage 2 forward cooling plates, P/N 6064T10P01, identified by serial numbers listed in Tables 1 and 2 of GE Aircraft Engines (CT7-TP Series) SB No. A72-381, dated January 17, 1996, for GE CT7-5A2, -7A, -9B, and -9C engine models.
(2) 12,000 CSN for GGT stage 2 forward cooling plates, P/N 6064T10P01 (not listed in (1) above), and P/N 5086T91P02, for GE CT7-5A2 and -7A engine models.
(3) 9,000 CSN for GGT stage 2 forward cooling plates, P/N 6064T10P01 (not listed in (1) above), and P/N 5086T91P02, for GE CT7-9B/-9C engine models.
(c) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Engine Certification Office. The request should be forwarded through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it tothe Manager, Engine Certification Office.
Note 2: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Engine Certification Office.
(d) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the aircraft to a location where the requirements of this AD can be accomplished.
(e) Thereafter, except as provided in paragraphs (c) and (d) of this AD, no alternative replacement times may be approved for GGT stage 2 forward cooling plates, P/N 6064T10P01, and P/N 5086T91P02.
(f) The actions required by this AD shall be done in accordance with the following GE Aircraft Engines (CT7-TP Series) SB:

Document No
Pages
Date
A72-381
1-13
January 17, 1996
Total Pages: 13.

This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from GE Aircraft Engines, 1000 Western Ave., Lynn, MA 01910; telephone (617) 594-3140, fax (617) 594-4805. Copies may be inspected at the FAA, New England Region, Office of the Assistant Chief Counsel, 12 New England Executive Park, Burlington, MA; or at the Office of the Federal Register, 800 North Capitol Street NW., suite 700, Washington, DC.
(g) This amendment becomes effective on March 10, 1997.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to General Electric Aircraft Engines (GE) CT7 series turboprop engines was published in the Federal Register on September 17, 1996 (61 FR 48866). That action proposed to require replacement of the gas generator turbine stage 2 forward cooling plate within 30 days after the effective date of the AD, or prior to reaching the new, reduced cyclic life limits listed in the Accomplishment Instructions of GE Aircraft Engines (CT7-TP Series) SB A72-381, dated January 17, 1996, whichever occurs later.
Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were received on the proposal or the FAA's determination of the cost to the public.
The FAA has determined that an additional paragraph (e) is necessary to fully implement the new life limits for gas generatorturbine (GGT) stage 2 forward cooling plates, Part Number (P/N) 6064T10P01 and P/N 5086T91P02. The FAA has determined that air safety and the public interest require the adoption of the rule with this change, and that this change will neither increase the economic burden on any operator nor increase the scope of the AD.
There are approximately 1,100 engines of the affected design in the worldwide fleet. The FAA estimates that 500 engines installed on aircraft of U.S. registry will be affected by this AD, that it will take approximately 8 work hours per engine to accomplish the required actions, and that the average labor rate is $60 per work hour. Parts will be supplied by the manufacturer to operators under GE's Engine Care Maintenance Plan (ECMP). At this time, all operators fall under the ECMP. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $240,000.
The regulations adopted herein will not have substantial direct effects on theStates, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.
For the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption "ADDRESSES." List of Subjects in 14 CFR Part 39
Air Transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.
Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows: PART 39 - AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 USC 106(g), 40113, 44701. 39.13 - [AMENDED]
2. Section 39.13 is amended by adding the following new airworthiness directive: