AD 97-19-17 ACTIVE

This amendment adopts a new airworthiness directive (AD), applicable to General Electric Company CT58 series turboshaft engines, that requires removal from service of certain compressor rear shafts, initial and repetitive inspections of specific critical rotating parts, and replacement if found cracked, until those parts are removed from service and replaced with improved design parts. This amendment is prompted by a stage 2 turbine wheel incident in 1993 which resulted in an increased awareness of small features on critical rotating parts which could affect part life. The actions specified by this AD are intended to prevent fatigue cracking on specific critical rotating parts, which could result in failure of the part, causing an uncontained engine failure and damage to the aircraft.

Final rule.

97-19-17 General Electric Company: Amendment 39-10137. Docket 97-ANE-15.
Applicability: General Electric Company (GE) Models CT58-100-2, -110-1/-2, -140-1/-2, and T58-GE-3/-5/-10/-100 turboshaft engines, 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 (f) 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 fatigue cracking on specific critical rotating parts, which could result in failure of the part, causing an uncontained engine failure and damage to the aircraft, accomplish the following:
(a) Determine hours time in service (TIS) and cycles in service (CIS) in accordance with the improved methodology described in GE Aircraft Engines Service Bulletin (SB) No. (CT58) A72-162, CEB-258, Revision 8, dated June 16, 1997.
(b) For engines that have engaged in repeated heavy lift (RHL) operations, as defined in paragraph (e) of this AD, accomplish the following:
(1) For compressor rear shafts, Part Numbers (P/N's) 4000T29P01/P03, 5016T95P01/P04, and 5013T86P03, accomplish the following:
(i) For compressor rear shafts, with either 2,975 or more hours TIS, or 9,550 or more CIS, on the effective date of this AD, remove compressorrear shafts and replace with a serviceable compressor rear shaft at the next light overhaul or next exposure of compressor rear shafts after the effective date of this AD, whichever occurs first.
(ii) For all other compressor rear shafts, remove compressor rear shafts and replace with a serviceable compressor rear shaft, prior to accumulating 3,000 hours TIS, or 9,600 CIS, whichever occurs first.
(iii) For all compressor rear shafts, remove from service and replace with a serviceable, redesigned compressor rear shaft, P/N 5016T95P06, not later than December 31, 1997.
(2) Initially inspect the ten rotating parts specified in paragraph (d) of this AD for cracks at the times specified in sub-paragraphs (i) and (ii) of this paragraph, and, thereafter, inspect at each light overhaul or major overhaul until the parts are retired from service. Perform the inspections in accordance with the procedures described in GE Aircraft Engines SB No. (CT58) 72-181, CEB-284, Revision 2, dated July 15, 1997. Prior to further flight, replace parts found cracked during these inspections with serviceable parts.
(i) For parts with greater than the baseline time in service (TIS) on the effective date of this AD, inspect at the earliest occurrence of the following after the effective date of this AD: the next light overhaul, the next major overhaul, or the next exposure of the affected parts.
(ii) For parts with less than or equal to the baseline TIS on the effective date of this AD, inspect within 1,000 hours TIS from the listed baseline TIS.
(c) For engines that have never engaged in RHL operations, accomplish the following:
(1) For compressor rear shafts, P/N's 4000T29P01/P03, 5016T95P01/P04, and 5013T86P03, remove compressor rear shafts and replace with a serviceable compressor rear shaft, prior to accumulating 9,600 CIS, or 9,000 hours TIS, whichever occurs first. Prior to December 31, 1999, replace compressor rear shafts with a serviceable, redesignedcompressor rear shaft, P/N 5016T95P06.
(2) Initially inspect the ten rotating parts specified in paragraph (d) of this AD for cracks at the times specified in sub-paragraphs (i) and (ii) of this paragraph, and, thereafter, at each light overhaul or major overhaul until the parts are retired from service. Perform the inspections in accordance with the procedures described in GE Aircraft Engines SB No. (CT58) 72-181, CEB-284, Revision 2, dated July 15, 1997. Prior to further flight, replace parts found cracked during these inspections with serviceable parts.
(i) For parts with greater than the baseline TIS on the effective date of this AD, inspect at the earliest occurrence of the following after the effective date of this AD: the next light overhaul, the next major overhaul, or the next exposure.
(ii) For parts with less than or equal to the baseline TIS on the effective date of this AD, inspect within 2,000 hours TIS from the listed baseline hours.
(d) For the purpose of performing the inspections required by paragraphs (b)(2) and (c)(2) of this AD, the following baseline TIS are established:
(1) For compressor rotor spool assemblies, P/N's 6010T57G04 and 6010T57G08, whether or not used in RHL operations, baseline is 2,000 hours TIS.
(2) For turbine front shafts, P/N's 5003T35P01 and 573D358P002, whether or not utilized in RHL operation, baseline is 1,000 hours TIS.
(3) For turbine coupling shafts, P/N's 4001T26P01 and 278D987P002, if utilized in RHL operation, baseline is 1,000 hours TIS; if never utilized in RHL operations, baseline is 2,000 hours TIS.
(4) For turbine rear shafts, P/N's 4005T29P01 and 37D400244P101, whether or not utilized in RHL operation, baseline is 2,000 hours TIS.
(5) For Stage 1 front cooling plates, P/N's 37C300055P101, whether or not utilized in RHL operation, baseline is 1,000 hours TIS.
(6) For Stage 1 aft cooling plates, P/N's 3002T25P01 and 645C334P002, whether or not utilized in RHL operation, baseline is 1,000 hours TIS.
(7) For Stage 2 front cooling plates, P/N's 3000T88P02 and 645C332P002, whether or not utilized in RHL operation, baseline is 1,000 hours TIS.
(8) For Stage 2 aft cooling plates, P/N's 3002T27P01 and 645C336P002, whether or not utilized in RHL operation, baseline is 1,000 hours TIS.
(9) For Stage 1 turbine wheels, P/N 4002T17P02 TF3, listed by Serial Numbers (S/Ns) in paragraph 1.A. (3) of GE Aircraft Engines SB No. (CT58) 72-181, CEB-284, Revision 2, dated July 15, 1997, if utilized in RHL operation, baseline is 1,000 hours TIS; if never utilized in RHL operation, baseline is 2,000 hours TIS.
(10) For Stage 2 turbine wheels, P/N 4002T96P02 TF3, listed by S/Ns in paragraph 1.A. (3) of GE Aircraft Engines SB No. (CT58) 72-181, CEB-284, Revision 2, dated July 15, 1997, if utilized in RHL operation, baseline is 1,000 hours TIS; if never utilized in RHL operation, baseline is 2,000 hours TIS.
(e) 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.
(3) Major overhaul is defined as scheduled engine maintenance including complete engine inspections and tests with repair or replacement of parts or components as necessary.
(f) 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 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.
(g) 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 inspection requirements of this AD can be accomplished.
(h) The actions required by this AD shall be done in accordance with the following GE Aircraft Engines SBs:

Document No.
Pages
Revision
Date
(CT58) 72-181 CEB-284
1-22
2
July 15, 1997
Total Pages: 22.

(CT58) A72-162 CEB-258
1
7
April 25, 1997

2,3
8
June 16, 1997

4,5
5
May 12, 1994

6
7
April 25, 1997

7,8
5
May 12, 1994

9-11
7
April 25, 1997

12-16
5
May 12, 1994

17
7
April 25, 1997

18-20
5
May 12, 1994

21
8
June 16, 1997

22-24
5
May 12, 1994

25,26
7
April 25, 1997

27
5
May 12, 1994
Total Pages: 27.

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 Aircraft Engines, Technical Publications, 1000 Western Avenue, Lynn, MA 01910; telephone (781) 594-5102, fax (781) 594-2717. 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.
(i) This amendment becomes effective on November 28, 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) CT58 series turboshaft engines was published in the Federal Register on April 3, 1997 (62 FR 15861). That action proposed to require removal from service of certain compressor rear shafts, initial and repetitive inspections of specific critical rotating parts, and replacement if found cracked, until those parts are removed from service and replaced with improved design 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 Notice of Proposed Rulemaking (NPRM), GE has issued Revision 2 to GE Aircraft Engines Service Bulletin (SB) No. (CT58) 72-181, CEB-284, dated July 15, 1997, which adds serial numbers (S/Ns) of certain affected Stage 1 and Stage 2 turbine wheels that require inspections. Revision 1 to GE Aircraft Engines SB No. (CT58) 72-181, CEB-284, dated November 29, 1995, is no longer current and is not an acceptable Alternative Method of Compliance (AMOC) for this AD.
In addition, GE has issued Revision 8 to GE Aircraft Engines SB No. (CT58) A72-162, CEB-258, dated June 16, 1997, that makes editorial changes to the SB. Revisions 5 through 7 of this SB are considered acceptable AMOCs for this AD.
Also, the FAA has revised the economic analysis to better reflect the lower number of affected engines, since not all Stage 1 and Stage 2 turbine wheels now require inspections, only those listed by S/Ns in GE Aircraft Engines SB No. (CT58) 72-181, CEB-284, dated July 15, 1997.
After careful review of the available data, the FAA has determined that air safety and the public interest require the adoption of the rule with the changes described previously. The FAA has determined that these changes will neither increase the economic burden on any operator nor increase the scope of the AD.
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 take approximately zero additional work hours per engine to accomplish the required actions. Required parts will cost approximately $2,730 per engine, based on the estimated current part cost, as the manufacturer will prorate the cost to the operator downward by a factor equal to the quotient of the difference between the original life limit (4,000 hours time in service) and the total cycles of life consumed at time of removal, divided by the original life limit. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $56,650.
The regulations adopted herein will not have substantial direct effects on the States, on the relationship betweenthe 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:

The service information referenced in this AD may be obtained from General Electric Aircraft Engines, Technical Publications, 1000 Western Avenue, Lynn, MA 01910; telephone (781) 594-5102, fax (781) 594-2717. This information may be examined at the Federal Aviation Administration (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.

Diane Cook, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone (781) 238-7133, fax (781) 238-7199.