AD 96-25-12

This amendment adopts a new airworthiness directive (AD) that is applicable to Sundstrand T-62T-40C series auxiliary power units (APUs). This action requires removal from service of certain compressor wheels in accordance with a drawdown schedule, and replacement with serviceable parts, and establishes a new cyclic life limit for the existing compressor wheels. This amendment is prompted by reports of compressor wheel ruptures. The actions specified in this AD are intended to prevent compressor wheel rupture, which could result in an uncontained APU failure and damage to the aircraft.

Final rule; request for comments.

96-25-12 SUNDSTRAND AEROSPACE: Amendment 39-9855. Docket 96-ANE-27. \n\n\tApplicability: Sundstrand Aerospace Models T-62T-40C series auxiliary power units (APUs), with compressor wheel, Part Numbers (P/Ns) 162690-1, 165111-1, and 167200-1. These APUs are installed on but not limited to Aerospatiale AS332 Super Puma, Boeing 707 series, British Aerospace HS 748 series, Cessna 650 series, General Dynamics 340, 440, and 880 series, Dassault Aviation Falcon 20, 50 and 200 series, de Havilland DHC-7 and DHC-8 series, Embraer 120 series, Fokker F.27 series, Gulfstream Aerospace Corporation 159, 1159, and G-III series, Raytheon Aircraft Company HS.125 700A, Lockheed-Georgia 1329 series, Raytheon Aircraft Company BAe 125 series, Sabreliner Corporation NA-265 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 compressor wheel rupture, which could result in an uncontained APU failure and damage to the aircraft, accomplish the following: \n\n\t(a)\tRemove from service compressor wheels in accordance with the procedures described in the Accomplishment Instructions of Sundstrand Aerospace Service Bulletin (SB) No. SB-T-62T-49-120, Revision 2, dated November 5, 1996, Revision 1, dated September 9, 1996, or Original, dated July 22, 1996, and the drawdown schedule described in Table 2 of Revision 2 only, dated November 5, 1996, and replace with serviceable parts. \n\n\t(b)\tThis AD establishes a new life limit of 6,000 cycles for existing uninstalled compressor wheels, identified as Sundstrand P/Ns 162690-1, 165111-1, and 167200-1. \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 methods of compliance with this airworthiness directive, 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)\tThereafter, except as provided in paragraphs (c) and (d) of this AD, no alternative replacement time may be approved for compressor wheels, identified as Sundstrand P/Ns 162690-1, 165111-1, and 167200-1. \n\n\t(f)\tThe actions required by this AD shall be done in accordance with the following Sundstrand Aerospace SBs: \n\n\nDocument No.\nRevision\nPages\nDate \nSB-T-62-T-49-120\n2\n1-9\nNovember 5, 1996 \nTotal pages: 9. \n\n\n\n\n\n\n\nSB-T-62-T-49-120\n1\n1-9\nSeptember 9, 1996 \nTotal pages: 9. \n\n\n\n\n\n\n\nSB-T-62-T-49-120\nOriginal\n1-9\nJuly 22, 1996 \nTotal pages\n\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 Sundstrand Aerospace, 4400Ruffin Rd., P.O. Box 85757, San Diego, CA 92186-5757; telephone (619) 627-6303, fax (619) 627-6473. 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 January 13, 1997.

The Federal Aviation Administration (FAA) has received three reports of compressor wheels, installed on Sundstrand T-62T-40C series auxiliary power units (APUs), that ruptured prior to the published cyclic life limit. Of the three ruptures, two were uncontained. The investigation revealed that the compressor wheels ruptured due to low cycle fatigue. This condition, if not corrected, could result in compressor wheel rupture, which could result in an uncontained APU failure and damage to the aircraft.\n\n\tThe FAA has reviewed and approved the technical contents of Sundstrand Aerospace Service Bulletin (SB) No. SB-T-62T-49-120, Revision 2, dated November 5, 1996, Revision 1, dated September 9, 1996, and Original, dated July 22, 1996, that describe procedures for removal from service of certain compressor wheels in accordance with a drawdown schedule, and replacement with new design serviceable parts, and establishes a new cyclic life limit for existing compressor wheels.\n\n\tSince an unsafe condition has been identified that is likely to exist or develop on other APUs of the same type design, this AD is being issued to prevent compressor wheel rupture. This AD requires removal from service of certain compressor wheels in accordance with a drawdown schedule, and replacement with serviceable parts, and establishes a new cyclic life limit for existing compressor wheels. The actions are required to be accomplished in accordance with the SB described previously.\n\n\tSince a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.\n\nComments Invited\n\tAlthough this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invitedon this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications should identify the Rules Docket number and be submitted in triplicate to the address specified under the caption "ADDRESSES." All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.\n\n\tComments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket.\n\n\tCommenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 96-ANE-27." The postcard will be date stamped and returned to the commenter.\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\tThe FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and is not a "significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, 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: