AD 96-18-17

This amendment adopts a new airworthiness directive (AD), applicable to AlliedSignal Inc. (formerly Garrett) TSCP700-4B, -4E, and -5 auxiliary power units (APUs), that requires removal from service of certain high pressure turbine (HPT) disks identified by serial number, and replacement with serviceable parts. This amendment is prompted by the discovery of a material defect in certain HPT disk forgings that may result in HPT disk rupture prior to reaching the disk cyclic life limit. The actions specified by this AD are intended to prevent an HPT disk rupture.

Final rule.

96-18-17 ALLIEDSIGNAL INC.: Amendment 39-9743. Docket 95-ANE-68. \n\n\tApplicability: AlliedSignal Inc. (formerly Garrett) Models TSCP700-4B, -4E, and -5 auxiliary power units (APUs), with high pressure turbine (HPT) disks identified by serial number in AlliedSignal Aerospace Service Bulletin (SB) No. TSCP700-49-A7168, dated November 7, 1995. These APUs are installed on, but not limited to, McDonnell Douglas DC-10, KC-10 (military), and MD-11 series, and Airbus A300 series aircraft. \n\n\tNote: 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 (d) of this AD. The request shouldinclude 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 an HPT disk rupture, accomplish the following: \n\n\t(a)\tPrior to accumulating 7,500 cycles since new (CSN), or 3 years after the effective date of this AD, whichever occurs first, remove from service affected HPT disks and replace with a serviceable part. \n\n\t(b)\tThe definition of a disk cycle may be found in the applicable AlliedSignal Inc. APU Component Maintenance Manual. \n\n\t(c)\tAuxiliary power unit maintenance records may be used to determine if the HPT disk installed in the APU has a serial number listed in AlliedSignal Aerospace SB No. TSCP700-49-A7168, dated November 7, 1995. \n\n\t(d)\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: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the Los Angeles Aircraft Certification Office. \n\n\t(e)\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(f)\tThe actions required by this AD shall be done in accordance with the following AlliedSignal Aerospace SB: \n\n\nDocument No\t\t \nPages\nDate\nTSCP700-49-A7168\n1-8\nNovember 7, 1995\n\nTotal Pages: 8.\n\n\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 Engines, P.O. Box 52181, Phoenix, AZ 85072-2181; telephone (800) 338-3378, fax (602) 231-4402. 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(g)\tThis amendment becomes effective on December 9, 1996.

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 AlliedSignal Inc. (formerly Garrett) Models TSCP700-4B, -4E, and -5 auxiliary power units (APUs) was published in the Federal Register on March 26, 1996 (61 FR 13113). That action proposed to require removal from service of certain high pressure turbine (HPT) disks identified by serial number, and replacement with serviceable parts, prior to accumulating 7,500 cycles since new (CSN), or 3 years after the effective date of this AD, whichever occurs first. The actions are required to be accomplished in accordance with AlliedSignal Aerospace Service Bulletin (SB) No. TSCP700-49-A7168, dated November 7, 1995.\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\tFour commenters support the rule as proposed.\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 as proposed.\n\n\tThere are approximately 31 APUs of the affected design in the worldwide fleet. The FAA estimates that 20 APUs installed on aircraft of U.S. registry will be affected by this AD, that it will take no additional work hours if the disk is replaced during overhaul. The manufacturer has advised the FAA that they will supply required parts at no charge to the operator. The FAA has therefore determined that this AD will impose no additional cost on U.S. operators.\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:\n\nPART 39 - AIRWORTHINESS DIRECTIVES\n\t1. The authority citation for part 39 continues to read as follows:\n\tAuthority: 49 USC 106(g), 40113, 44701.\n\n§39.13 - (AMENDED)\n\t2. Section 39.13 is amended by adding the following new airworthiness directive: