4th Stage LPT Hub

Category - Engine
Effective Date - 11/18/1997
Recurring - Yes
Supersedes -N/A
Superseded by - N/A
Amendment 39-10133.
Docket 96-ANE-32.

Applicability: Pratt & Whitney (PW) Models JT8D-1, -1A, -1B, -7, -7A, -7B, 9, -9A, -11, -15, -17, and -17R turbofan engines, with 4th stage low pressure turbine (LPT) hubs identified by serial number (S/N) in Table A of PW Alert Service Bulletin (ASB) No. A6274, Revision 1, dated December 9, 1996. These engines are installed on but not limited to Boeing 727 and 737 series, and McDonnell Douglas DC-9 series aircraft.

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 4th stage LPT blade failure due to hub cracking, which can result in an uncontained engine failure and damage to the aircraft, accomplish the following:

(a) Perform fluorescent penetrant inspection (FPI) and eddy current inspection (ECI) of affected 4th stage LPT hubs for cracks, in accordance with Paragraph 2A of PW ASB No. A6274, Revision 1, dated December 9, 1996, as follows:

(1) Inspect at the next time after the effective date of this AD that the hub is removed from the module and has been debladed.

(2) Thereafter, inspect each time the hub is removed from the module and has been debladed.

(3) Remove from service any cracked 4th stage LPT hub and replace with a serviceable part.

(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 forward 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 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

A6274...............   1-23    1            December 9, 1996.

Total Pages: 23.

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, Publication 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 November 18, 1997.

FOR FURTHER INFORMATION CONTACT:

Christopher Spinney, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone (781) 238-7175, fax (781) 238-7199.