2007-17-21: High pressure turbine (HPT) vane assemblies

2007-17-21 Pratt & Whitney: Amendment 39-15180. Docket No. FAA-2006- 23742; Directorate Identifier 2005-NE-53-AD. Effective Date (a) This airworthiness directive (AD) becomes effective September 28, 2007. Affected ADs (b) None. Applicability (c) This AD applies to Pratt & Whitney (PW) JT9D-7R4G2, -7R4E1, -7R4E4, and -7R4H1 series turbofan engines. These engines are installed on, but not limited to, Boeing 747-200, -300, 767-200, and Airbus A300-600 and A310-300 series airplanes. Unsafe Condition (d) This AD results from a report of an uncontained failure of the 2nd stage high pressure turbine (HPT) air seal assembly, caused by the air seal assembly brace disengaging from the air seal, due to insufficient cooling air flow. We are issuing this AD to prevent uncontained failure of the 2nd stage HPT air seal assembly, leading to engine in-flight shutdown and damage to the airplane. Compliance (e) You are responsible for having the actions required by this AD performed at the next HPT module exposure after the effective date of this AD, unless the actions have already been done. (f) At the next HPT module exposure, remove reduced cooling flow 2nd stage HPT vane assemblies part numbers (P/Ns): 797282, 796972, 800082, 800072, 803182, 803282, and 822582, installed in 2nd stage HPT vane cluster assemblies: P/Ns 797592, 797372, 799872, 799782, and 822572. (g) For 2nd stage HPT air seals that have operated in an engine with reduced cooling flow HPT vane assemblies, at the next HPT module exposure do the following: (1) Perform a onetime visual inspection of the 2nd stage HPT air seal assembly, P/N 815097, using instructions in JT9D-7R4 engine manual, Section 72-51-22, Inspection/Check-01, paragraphs 1.D.(1), 1.D.(4), and 1.D.(6). (2) Perform a fluorescent penetrant inspection (FPI) of the 2nd stage HPT air seal assembly for cracks, using instructions in JT9D- 7R4 engine manual, Section 71-51-00, Inspection/Check-03. Definition (h) For the purpose of this AD, an HPT module exposure is defined as removing the 1st stage HPT rotor or the 2nd stage HPT rotor from the HPT case. Alternative Methods of Compliance (i) The Manager, Engine Certification Office, has the authority to approve alternative methods of compliance for this AD if requested using the procedures found in 14 CFR 39.19. Related Information (j) Pratt & Whitney Alert Service Bulletin JT9D-7R4-A72-596, dated September 15, 2005, contains information for modifying the reduced cooling flow 2nd stage HPT vane assemblies.