99-22-10: High Pressure Compressor (HPC) Spool and Disk

99-22-10 GENERAL ELECTRIC AIRCRAFT ENGINES: Amendment 39-11388. Docket 98-ANE-62-AD. Issued October 18, 1999. Applicability: General Electric Aircraft Engines (GEAE) Models CF34-1A, -3A, -3A1, and -3A2 turbofan engines, installed on but not limited to Canadair aircraft models CL-600-2A12, -2B16, and -2B19. 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 (b) 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 high pressure compressor (HPC) spool and disk cracking, which could result in an uncontained engine failure and damage to the aircraft, accomplish the following: (a) Remove from service the following HPC spools and disks prior to accumulating cycles in service beyond new, reduced cyclic life limits, and replace with a serviceable part, as follows: (1) For forward HPC spools, part number (P/N) 6078T56P01, which have accumulated fewer than 6,000 cycles since new (CSN) on the effective date of this AD, remove prior to accumulating 6,000 CSN. (2) For forward HPC spools, P/N 6078T56P01, which have accumulated 6,000 or more CSN on the effective date of this AD, remove at the next shop visit after the effective date of this AD, but prior to accumulating 12,000 CSN. (3) For the purpose of this AD, engine shop visit is defined as engine disassembly that includes separation of the compressor section from the fan section front frame and from the combustion section combustion chamber frame. (4) For stage 9 HPC disks, P/N 6087T01P03 or 6087T01P04, remove prior to accumulating 20,000 CSN. (5) For rear HPC spools, P/N 5087T46P01 or 5087T46P02, remove prior to accumulating 17,000 CSN. (b) 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. Operators shall submit their requests 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. (c) Special flight permits may be issued in accordance withsections 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. (d) This amendment becomes effective on December 27, 1999.