AD 97-04-04

This amendment supersedes an existing airworthiness directive (AD), applicable to AlliedSignal Inc. (formerly Garrett Auxiliary Power Division) GTCP85 Series auxiliary power units (APUs), that currently requires removing the existing turbine wheel shroud and installing one constructed of Hastelloy "S" material, or installing a containment augmentation ring. This amendment deletes the option of installing a turbine shroud constructed of Hastelloy "S" material. This amendment is prompted by a report of insufficient APU containment capability with the Hastelloy "S" shroud alone installed. The actions specified by this AD are intended to prevent turbine shroud fragments from exiting the APU and puncturing the APU compartment, which could result in reduced fire extinguishing capability in the APU compartment.

Final rule.

97-04-04 AlliedSignal Inc.: Amendment 39-9927. Docket 96-ANE-15. Supersedes AD 93-07-13, Amendment 39-8545. \n\n\tApplicability: AlliedSignal Inc. (formerly Garrett Auxiliary Power Division) GTCP85 series auxiliary power units (APUs), incorporating a one-piece cast turbine wheel, Part Numbers (P/Ns) 968095-X, 3604604-X, 3606982-1, or 3842072-X (where "X" denotes any number). These APUs are installed on but not limited to the following aircraft: British Aerospace BAC 1-11 series; Boeing 707, 727, and 737 series; Lockheed 382 series; and McDonnell Douglas DC-8-70, DC-9, and MD-88 series aircraft.\n\n\tNote 1: This airworthiness directive (AD) applies to each APU 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 APUs 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.\n \n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tTo prevent turbine shroud fragments from exiting the APU and puncturing the APU compartment, which could result in reduced fire extinguishing capability in the APU compartment, accomplish the following: \n\n\t(a)\tFor flight operable APUs, within 24 months after the effective date of this AD, accomplish either of the following: \n\n\t\t(1)\tInstall a containment augmentation ring, P/N 3616426-3, in accordance with AlliedSignal Aerospace Alert Service Bulletin (ASB) No. GTCP85-49-A7189, Revision 2, dated October 8, 1996, Revision 1, dated July 19, 1996, or Original, dated March 29, 1996; or \n\n\t\t(2)\tInstall a containment augmentation ring, P/N 3616426-1, in accordance with AlliedSignal Aerospace ASB No. GTCP85-49-A6706, Revision 2, dated November 28, 1994, AlliedSignal Aerospace ASB No. GTCP85-49-A6706, Revision 1, dated November 12, 1993, or Garrett ASB No. GTCP85-49-A6706, Original, dated December 7, 1992.\n\n\t(b)\tFor APUs that are operable on the ground only, within 36 months after the effective date of this AD, accomplish either of the following:\n \n\t\t(1)\tInstall a containment augmentation ring, P/N 3616426-3, in accordance with AlliedSignal Aerospace ASB No. GTCP85-49-A7189, Revision 2, dated October 8, 1996, Revision 1, dated July 19, 1996, or Original, dated March 29, 1996; or \n\n\t\t(2)\tInstall a containment augmentation ring, P/N 3616426-1, in accordance with AlliedSignal Aerospace ASB No. GTCP85-49-A6706, Revision 2, dated November 28, 1994, AlliedSignal Aerospace ASB No. GTCP85-49-A6706, Revision 1, dated November 12, 1993, orGarrett ASB No. GTCP85-49-A6706, Original, dated December 7, 1992. \n\n\t(c)\tAn 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, Los Angeles Aircraft 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, Los Angeles Aircraft Certification Office. \n\n\tNote 2: Information concerning the existence of approved alternative method of compliance with this AD, if any, may be obtained from the Los Angeles Aircraft Certification Office.\n \n\t(d)\tSpecial 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. \n\n\t(e)\tThe actions required by this AD shall be done in accordance with the following ASBs:Document No.\t\nPages\nRevision\nDate \nAlliedSignal Aerospace GTCP85-49-A7189\n1-14\n2\nOctober 8, 1996 \nTotal pages: 14. \n\n\n\nAlliedSignal Aerospace GTCP85-49-A7189\n1-12\n1\t\nJuly 19, 1996 \nTotal pages: 12. \n\n\n\nAlliedSignal Aerospace GTCP85-49-A7189\n1-10\nOriginal\nMarch 29, 1996 \nTotal pages: 10. \n\n\n\nAlliedSignal Aerospace GTCP85-49-A6706\t\n1\n2\nNovember 28, 1994 \n\n2,3\n1\nNovember 12, 1993 \n\n4\n2\nNovember 28, 1994 \n\n5-8\n1\nNovember 12, 1993 \n\n9,10\n2\nNovember 28, 1994 \nTotal pages: 10. \n\n\n\nAlliedSignal Aerospace GTCP85-49-A6706\n1-10\t1\t\tNovember 12, 1993 \n1-10\t1\t\tNovember 12, 1993 \n1-10\t1\t\tNovember 12, 1993 \nTotal pages: 10. \n\n\n\nGarrett GTCP85-49-A6706\n1,2\nOriginal\nDecember 7, 1992 \n\n4-10\nOriginal\nDecember 7, 1992 \nTotal pages: 9. \n\n\n\n\t\t\t\t\n\nThis 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 AlliedSignal Aerospace, Attn: Data Distribution, M/S 64-3/2101-201, P.O. Box 29003, Phoenix, AZ 85038-9003; telephone (602) 365-2493, fax (602) 365-5577. 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. \n\n\t(f)\tThis amendment becomes effective on March 24, 1997.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 93-07-13, Amendment 39-8545 (58 FR 21917, April 26, 1993), which is applicable to AlliedSignal Inc. (formerly Garrett Auxiliary Power Division) GTCP85 Series auxiliary power units (APUs), was published in the Federal Register on August 12, 1996 (61 FR 41751). That action proposed to require installing an improved containment augmentation ring, Part Number (P/N) 3616426-1, or P/N 3616426-3, which is a redesigned containment augmentation ring to allow installation on certain APUs that cannot accept the -1 containment augmentation ring. The containment augmentation rings, P/Ns 3616426-1 and 3616426-3, improve the containment capability of the APU relative to the earlier containment augmentation ring, P/N 3612249-1, by preventing turbine shroud fragments from passing around the containment augmentation ring. The installation must be accomplished within 24 months after the effective date of this AD, for flight operable APUs, and within 36 months after the effective date of this AD, for APUs that are operable on the ground only. The actions would be required to be accomplished in accordance with AlliedSignal Aerospace Alert Service Bulletin (ASB) No. GTCP85- 49-A7189, Revision 2, dated October 8, 1996, AlliedSignal Aerospace ASB No. GTCP85-49-A7189, Revision 1, dated July 19, 1996, or AlliedSignal Aerospace ASB No. GTCP85-49-A7189, Original, dated March 29, 1996; and AlliedSignal Aerospace ASB No. GTCP85-49-A6706, Revision 2, dated November 28, 1994, AlliedSignal Aerospace ASB No. GTCP85-49-A6706, Revision 1, dated November 12, 1993, or Garrett ASB No. GTCP85-49-A6706, Original, dated December 7, 1992.\n \n\tInterested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received.\n \n\tOne commenter states that the AD should apply only to APUs with one-piece cast turbine wheels made of MAR-M-247 material, as only these type turbine wheels have failed in the commenter's experience. The FAA concurs in part. The proposed rule as written applies to APUs with one-piece cast turbine wheels with the listed P/Ns, which are made of MAR-M-247 material, but also Inconel, which have failed as well.\n \n\tTwo commenters state that the AD should add an additional method of compliance by replacing the one-piece cast turbine wheels with two-piece wheels. The FAA does not concur. The proposed AD does not apply to APUs with two-piece turbine wheels.\n \n\tOne commenter (the manufacturer) states that the economic analysis provides figures for the number of APUs in service domestically and worldwide that are too low. The FAA concurs and revised the economic analysis of this final rule accordingly.\n \n\tOne commenter states that the proposed AD should be more clear in stating that compliance is acceptable with either ASB stated in paragraphs (a)(1) and (a)(2) and (b)(1) and (b)(2) of the compliance section. The FAA concurs and has put the "or" between the appropriate paragraphs in bold type to highlight its significance\n \n\tTwo commenters concur with the AD as proposed.\n\n\tSince publication of the proposed rule, AlliedSignal Aerospace has issued Revision 2 to ASB No. GTCP85-49-A7189, dated October 8, 1996, which is referenced in this final rule along with Revision 1, dated July 19, 1996, and Original, dated March 29, 1996. These revisions of that ASB are all approved methods of compliance for the appropriate paragraphs of this AD.\n\n\tAfter careful review of the available data, including the comments noted above, 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.\n\n\tThere are approximately 4,100 APUs of the affected design in the worldwide fleet. The FAA estimates that 1,300 APUs installed on aircraft of U.S. registry will be affected by this AD, that it will take no additional work hours if the required actions are accomplished when the APU is already disassembled in the shop. Required parts will cost approximately $1,550 per APU. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $2,015,000. \n\n\tThe 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. \n\n\tFor 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." \n\nList of Subjects in 14 CFR Part 39 \n\tAir Transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.\n\nAdoption of the Amendment \n\tAccordingly, 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 \n\t1. The authority citation for part 39 continues to read as follows: \n\tAuthority: 49 USC 106(g), 40113, 44701. § 39.13 - (AMENDED) \n\t2. Section 39.13 is amended by removing Amendment 39-8545 (52 FR 45163, November 25, 1987) and by adding a new airworthiness directive, Amendment 39-9927, to read as follows: