AD 98-23-08 Airworthiness Directives; Pratt & Whitney PW4000 Series Turbofan Engines

Models named: PW4152, PW4056, PW4156, PW4256, PW4052, PW4158, PW4060, PW4160, PW4460, PW4050. Read the applicability below — it usually turns on serial or part numbers too.

Pratt & Whitney (PW) Model PW4152, PW4056, PW4156, PW4256, PW4052, PW4158, PW4060, PW4160, PW4460, PW4050, PW4060A, PW4156A, PW4062, PW4462, PW4060C, and PW4650 turbofan engines, not incorporating at least one of the modifications described in the PW service bulletins (SBs) and listed in items (1) through (6), excluding those engines having a (-3) identifier next to the engine model number on the engine data plate. These engines are installed on but not limited to Boeing 767 and 747 series aircraft, McDonnell Douglas MD-11 series aircraft, and Airbus A310 and A300-600 series aircraft. (1) PW4ENG 72-484, Revision 3, dated July 1, 1997, or earlier revisions, PW4ENG 72-486, Revision 1, dated November 23, 1994, or original issue. (2) PW4ENG 72-484, Revision 3, dated July 1, 1997, or earlier revisions, PW4ENG 72-575, Revision 1, dated June 30, 1997, or original issue, PW4ENG 72-486, Revision 1, dated November 23, 1994, or original issue. (3) PW4ENG 72-514, Revision 1, dated August 2, 1996, or original issue. (4) PW4ENG 72-490, Revision 1, dated August 2, 1994, or original issue. (5) PW4ENG 72-504, Revision 1, dated May 9, 1995, or original issue. (6) PW4ENG 72-572, dated June 16, 1995. 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.

Required as indicated, unless accomplished previously. To prevent high pressure compressor (HPC) surge, which can result in engine power loss at a critical phase of flight such as takeoff, accomplish the following: (a) Within 1,400 cycles in service (CIS) after the effective date of this AD, or prior to June 30, 1999, whichever occurs first, perform the following modifications: (1) Incorporate stage 9 through 12 aluminum oxide blade tips and grind HPC [[Page 63393]] blade tips at the rotor assembly in accordance with the Accomplishment Instructions of PW SB No. PW4ENG-72-484, Revision 3, dated July 1, 1997, concurrently with the requirements of paragraph (a)(4) of this AD. (2) Modify HPC 8th-14th stage stators in accordance with the Accomplishment Instructions of PW SB No. PW4ENG-72-486, Revision 1, dated November 23, 1994. (3) Modify the 1st stage high pressure turbine (HPT) cooling duct (TOBI Duct), install a metering plug in the Number 2 bearing thrust balance vent tube, and incorporate 1st stage HPT vanes with increased airflow area in accordance with the Accomplishment Instructions of PW SB No. PW4ENG-72-514, Revision 1, dated August 2, 1996. (4) Incorporate HPC 13th-15th stage zirconium oxide blade tips in accordance with the Accomplishment Instructions of PW SB No. PW4ENG-72-575, Revision 1, dated June 30, 1997. (5) If at any time prior to the compliance time of this AD incorporation of the requirements of any one of the SBs, identified in items (4), (5), and (6) in the applicability section of this AD is accomplished on any engine, then such an engine will not be subject to the requirements of this AD and no further action is required. (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 submit their request 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 SBs: ---------------------------------------------------------------------------------------------------------------- Document No. Pages Revision Date ---------------------------------------------------------------------------------------------------------------- PW4ENG-72-484.................. 1-16................... 3...................... July 1, 1997. 17-78.................. 1...................... November 8, 1994. 79..................... 2...................... March 10, 1995. 80, 81................. 3...................... July 1, 1997. Total Pages: 81. PW4ENG-72-486.................. 1-31................... 1...................... November 23, 1994. Total Pages: 31. PW4ENG-72-514.................. 1-6.................... 1...................... August 2, 1996. 7...................... Original............... June 23, 1994. 8-35................... 1...................... August 2, 1996. Total Pages: 35. PW4ENG-72-575.................. 1-43................... 1...................... June 30, 1997. Total Pages: 43. ---------------------------------------------------------------------------------------------------------------- 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, 400 Main St., East Hartford, CT 06108; telephone (860) 565-6600, fax (860) 565- 4503. Copies may be inspected at the FAA, New England Region, Office of the Regional 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 12, 1999. Issued in Burlington, Massachusetts, on November 5, 1998. Mark C. Fulmer, Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service. [FR Doc. 98-30320 Filed 11-12-98; 8:45 am] BILLING CODE 4910-13-P