Compressor Disks

Category - Engine
Effective Date - 09/11/1995
Recurring - Yes
Supersedes - 81-08-02 R2
Superseded by - N/A
Amendment 39-9327.
Docket 81-ANE-03.
Supersedes AD 81-08-02 R2, Amendment 39-4817.

Applicability: Pratt & Whitney (PW) JT8D-1, -1A, -7,-7A, -7B, -9, -9A, -11,-15, -15A, -17,-17A. -17R, and -17AR turbofan engines with 9th through 12th stage high pressure compressor (HPC) disks specified in Tables I through V and Table VIII of PW Alert Service Bulletin (ASB) No. 4723, Revision 12, dated March 8, 1990, installed. These engines are installed on but not limited to Boeing 727 series and 737 series, and McDonnell Douglas DC-9 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 use the authority provided in paragraph (e) to request approval from the Federal Aviation Administration (FAA). This approval may address either no action, if the current configuration eliminates the unsafe condition, or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any engine from the applicability of this AD.

Compliance: Required as indicated, unless accomplished previously in accordance with PW ASB No. 4723, Revision 9, dated July 13, 1983; Revision 10, dated September 15, 1986; or Revision 11, dated October 30, 1987. All inspections subsequent to the effective date of this AD must be accomplished in accordance with the methods and intervals identified in PW ASB No. 4723, Revision 12, dated March 8, 1990, except as is specified in paragraph (d) of this AD.

To prevent uncontained fractures of 9th through 12th stage HPC disks and engine failure, accomplish the following:

(a) Initially inspect 9th through 12th stage HPC disks at the tie rod holes in accordance with Tables I through V and Table VIII of PW ASB No.4273, Revision 12, dated March 8, 1990.

(b) Thereafter, inspect 9th through 12th stage HPC disks at the tierod holes in accordance with Tables I through V and Table VIII of PW ASB No. 4723, Revision 12, dated March 8, 1990. Disks initially inspected prior to the first inspection limit must be reinspected before reaching the specified reinspection interval, or before reaching the first inspection limit, whichever is later. In no case shall the established life limits of the disks be exceeded.

(c) Remove cracked disks from service prior to further flight, and replace with a serviceable part. Disks may be returned to service if repaired in accordance with Paragraph 7 of PW ASB No. 4723, Revision 12, dated March 8, 1990.

(d) For 10th stage HPC disks that were last inspected in accordance with the on-wing ultrasonic inspection procedure specified in AD 81-08-02 R2 prior to the effective date of this AD, inspect as follows:

(1) Perform a magnetic particle inspection or eddy current inspection in accordance with the procedure defined in Paragraph 6 and Appendix B or PW ASB No. 4723, Revision 12, dated March 8, 1990, no later than 750 cycles in service (CIS) since the last on-wing inspection.

(2) Accomplish all subsequent inspections in accordance with the methods and intervals specified in PW ASB No. 4723, Revision 12, dated March 8, 1990.

(e) 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 approved alternative method of compliance with this AD, if any, may be obtained from the Engine Certification Office.

(f) 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.

(g) The actions required by this AD shall be done in accordance with the following ASB:

Document No.               Pages            Rev.            Date

PW ASB No. 4723            1                12              Mar. 8, 1990.
                           2-8              10              Sept. 15, 1986.
                           9-10             11              Oct. 30, 1987.
                           11-25            10              Sept. 15, 1986.
Appendix A                 A-1              10              Sept. 15, 1986.
                           A-2  
Appendix B                 B-1- B-9         7               Feb. 16, 1981.
                           B-10             8               July 9, 1982
                           B-11-B-12        7               Feb. 16, 1981.
Total pages: 38.

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, Technical Publications Department, M/S 132-30, 400 Main Street, East Hartford, CT 06108. 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.

(h) This amendment becomes effective on September 11, 1995.

FOR FURTHER INFORMATION CONTACT:

Mark A. Rumizen, Aerospace Engineer Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone (617) 238-7137; fax (617) 238-7199.