96-23-10: Steel High Pressure Compressor (HPC) disk

96-23-10 Pratt & Whitney: Amendment 39-9815. Docket 95-ANE-45. Applicability: Pratt & Whitney (PW) Models JT3D-1, -1A, -3, -3B, -3C, -1-MC6, -1A-MC6, -1-MC7, -1A-MC7, -7, -7A turbofan engines, installed on but not limited to Boeing 707 and 720 series aircraft and McDonnell Douglas DC-8 series aircraft. Note: 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 steel high pressure compressor (HPC) disk failure due to corrosion, which could result in an uncontained engine failure and damage to the aircraft, accomplish the following: (a) Inspect steel HPC disks, stages 10-15, for corrosion, recoat or replate, or replace as necessary, in accordance with PW Alert Service Bulletin (ASB) No. A6208, Revision 3, dated January 11, 1996, and the following schedule: (1) For disks coated with PWA 110-2/-3 Aluminide (non top coat system) and for disks with unknown coating or plating, as follows: (i) Initially inspect, recoat or replate, or replace as necessary, within 14 years since new or since last recoat or replate, or within 36 months after the effective date of this AD, whichever occurs later. (ii) Thereafter, inspect, recoat or replate, or replace as necessary, at intervals not to exceed 14 years since new or last coating, if PWA 110-2/-3 Aluminide (non top coat system) is applied, or not to exceed 15 years since new or last plating, if PWA 110-21/-31 Aluminide (top coat system) or Nickel Cadmium (NI-CAD) plating is applied. (2) For disks coated with PWA 110-21/-31 Aluminide (top coat system) or plated with NI-CAD, as follows: (i) Initially inspect, recoat or replate, or replace as necessary, within 15 years since new or since last replate, or within 36 months after the effective date of this AD, whichever occurs later. (ii) Thereafter, inspect, recoat or replate, or replace as necessary, at intervals not to exceed 14 years since new or last coating, if PWA 110-2/-3 Aluminide (non top coat system) is applied, or not to exceed 15 years since new or last plating, if PWA 110-21/-31 Aluminide (top coat system) or Nickel Cadmium (NI-CAD) plating is applied. (3) For disks with unknown coating or plating, and unknown time since last coating or plating;or for disks with known coating or plating and unknown time since last coating or plating, as follows: (i) Initially inspect, recoat or replate, or replace as necessary, within 36 months after the effective date of this AD. (ii) Thereafter, inspect, recoat or replate, or replace as necessary, at intervals not to exceed 14 years since new or last coating, if PWA 110-2/-3 Aluminide (non top coat system) is applied, or not to exceed 15 years since new or last plating, if PWA 110-21/-31 Aluminide (top coat system) or Nickel Cadmium (NI-CAD) plating is applied. (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. 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: Information concerning the existence of approvedalternative 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 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. (d) The actions required by this AD shall be done in accordance with the following PW ASB: Document No Pages Revision Date A6208 1 3 January 11, 1996 2 1 May 8, 1995 3 3 January 11, 1996 4 1 May 8, 1995 5-9 3 January 11, 1996 10-18 1 May 8, 1995 Total Pages: 18. 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 Pratt & Whitney, Publications Department, Supervisor Technical Publications Distribution, M/S 132-30, 400 Main St., East Hartford,CT 06108; telephone (860) 565-7700, fax (860) 565-4503. 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. (e) This amendment becomes effective on January 21, 1997.