AD 2001-17-30 Airworthiness Directives; Pratt & Whitney JT9D-7R4 Series Turbofan Engines

This airworthiness directive (AD) is applicable to Pratt & Whitney (PW) JT9D-7R4 series turbofan engines. These engines are installed on, but not limited to, Boeing 747 and 767 series and Airbus A300 and A310 series airplanes. Note 1: This 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 (f) 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 with this AD is required as indicated, unless accomplished previously. To prevent high pressure turbine (HPT) disk firtree fracture, which could result in an uncontained engine failure, and damage to the airplane, accomplish the following: HPT 1st Stage Airseal Replacement (a) For engines that incorporate HPT 1st stage disk assembly part number (P/N) 787521, replace HPT 1st stage airseals with P/N 820121 at the next disk piece-part opportunity. Information on replacement of the HPT 1st stage airseal is contained in PW service bulletin (SB) JT9D-7R4-72-566, dated May 26, 2000. Fluorescent Penetrant Inspection (FPI) (b) Perform fluorescent penetrant inspection of the HPT 1st stage disk aft lug fillet radius for cracks according to the following Table 1 of this AD: Table 1 HPT 1st stage disk assembly HPT 1st stage disk Initial inspection Repetitive inspection interval (1) P/N 787521 P/N 825701 or P/N 827201 Before the latest of 4,000 CSN or 4,000 cycles since last HPT disk lug FPI (CSLI), or 500 CIS after the effective date of this AD Within 4,000 CSLI. (2) P/N 797621 (i) P/N 829401 with air seals P/N's 797355, 796760, 803979, 797355-001 installed Before the latest of 5,000 CSN or CSLI, or 500 CIS after the effective date of this AD Within 4,000 CSLI. (ii) P/N 829401 with air seals P/N 820121 installed Before the latest of 5,000 CSN or 5,000 CSLI, or 500 CIS after the effective date of this AD Within 6,000 CSLI. Additional inspection information can be found in Paragraph 4 of the Accomplishment Instructions of PW SB JT9D-7R4-72-567, dated May 26, 2000. (c) Replace any disks that have crack indications. Information on replacement of the disk is contained in PW SB JT9D-7R4-72-568, dated May 26, 2000. Terminating Action (d) Installation of HPT disk P/N 820321 with redesigned HPT 1st stage airseal P/N 820121 is considered terminating action to the initial and repetitive inspection requirements of paragraph (b) this AD. Information on installation of the HPT disk is contained in PW SB JT9D-7R4-72-568, dated May 26, 2000. Definition (e) For the purpose of this AD, at disk piece-part opportunity is defined as any time the 1st stage HPT rotor is disassembled. Alternative Methods of Compliance (f) 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 (ECO). Operators must submit their request through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, ECO. Note 2: Information concerning the existence of approved alternative methods of compliance with this airworthiness directive, if any, may be obtained from the ECO. Special Flight Permits (g) 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. Effective Date of this AD (h) This amendment becomes effective on October 4, 2001. Issued in Burlington, Massachusetts, on August 21, 2001. Donald Plouffe, Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service. [FR Doc. 01-21893 Filed 8-29-01; 8:45 am] BILLING CODE 4910-13-P