AD 97-21-08

This amendment adopts a new airworthiness directive (AD), applicable to General Electric Company CT58 series turboshaft engines, that requires removal from service of certain stage 1 and 2 forward cooling plates, and stage 2 aft cooling plates, and replacement with serviceable parts. This amendment is prompted by reports of certain cooling plates forged with contaminated alloy that could reduce the lives of the parts. The actions specified by this AD are intended to prevent cooling plate fracture, which could result in a contained engine failure, and an inflight engine shutdown.

Final rule.

97-21-08 General Electric Company: Amendment 39-10161. Docket 97-ANE-18-AD.
Applicability: General Electric Company (GE) Models CT58-110-1, -110-2, -140-1, and -140-2, and T58-GE-3/-5/-8F/-10/-100 series turboshaft engines, with stage 1 forward cooling plate, Part Number (P/N) 37C300055P101, stage 2 forward cooling plate, P/N 3000T88P02, and stage 2 aft cooling plate, P/N 3002T27P01, installed. These engines are installed on but not limited to Boeing Vertol 107 series, and Sikorsky S61 and S62 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 of the 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 cooling plate fracture, which could result in a contained engine failure and an inflight engine shutdown, accomplish the following:
(a) Remove from service affected cooling plates, listed by serial number in GE Aircraft Engines CT58 Service Bulletin (SB) No. 72-188 (CEB-293), Revision 1, dated July 15, 1997, and replace with serviceable parts, at the next part exposure, or next light overhaul, whichever occurs first, but not to exceed 1,000 hours time in service (TIS) for engines installed on aircraft that have engaged in Repetitive Heavy Lift (RHL) operations, or 2,000 hours TIS for engines installed on aircraft that have never engaged in RHL operations, in accordance with that SB.
(b) For the purpose of this AD, the following definitions apply:
(1) RHL operation is defined as performing more than 10 lift-carry-drop cycles per hour TIS without landing, or more than 10 takeoffs and landings per hour TIS.
(2) Light overhaul is defined as scheduled engine maintenance that allows the engine to continue in service until scheduled major overhaul time is reached.
(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 shall be forwarded through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the 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) The actions required by this AD shall be done in accordance with the following GE Aircraft Engines SB:

Document No
Pages
Revision
Date
72-188 (CEB-293)
1-7
1
July 15, 1997
Total Pages: 7.

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 General Electric Company (GE), 1000 Western Ave., Lynn, MA 01909; telephone (781) 594-9894, fax (781) 594-1527. 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.
(f) This amendment becomes effective on December 19, 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 Company (GE) Models CT58-110-1, -110-2, -140-1, -140-2, and T58-GE-3/-5/-8F/-10/-100 turboshaft engines was published in the Federal Register on June 9, 1997 (62 FR 31370). That action proposed to require removal from service of certain stage 1 and 2 forward cooling plates, and stage 2 aft cooling plates, and replacement with serviceable parts.
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.
Since publication of the proposed rule, GE Aircraft Engines has issued GE Aircraft Engines CT58 Service Bulletin (SB) No. 72-188 (CEB-293), Revision 1, dated July 15, 1997. This final rule references this current revision.
The FAA has determined that air safety and the public interest require the adoption of the rule with the changes described previously.
There are approximately 400 engines of the affected design in the worldwide fleet. The FAA estimates that 126 engines installed on aircraft of U.S. registry will be affected by this AD, that it will not take any additional work hours per engine to accomplish the required actions at next part exposure. Required parts will cost approximately $2,730 per engine. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $343,980. The manufacturer, however, has advised the FAA of a program to prorate the cost of required parts downward by a factor equal to the quotient of the difference between the original life limit of 4,000 hours time in service and the total cycles of life consumed at time of removal, divided by the original life limit. Therefore, the actual cost to operators may be less than the FAA's estimate.
The regulations adopted herein will not have substantial direct effects on the States, 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 U.S.C. 106(g), 40113, 44701. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: