2000-22-01: High Pressure Compressor Cutback Stator

2000-22-01 Pratt & Whitney: Amendment 39-11947. Docket 2000-NE-47-AD. Applicability This airworthiness directive (AD) is applicable to PW4050, PW4052, PW4056, PW4060, PW4060A, PW4060C, PW4062, PW4460, and PW4462 turbofan engines that have high pressure compressor (HPC) modules that have incorporated Pratt & Whitney (PW) cutback stator (CBS) configuration service bulletin (SB) PW4ENG 72-706, Revision 3, dated July 17, 2000, or earlier Revision, or SB PW4ENG 72-711, dated June 13, 2000. These engines are used on, but not limited to, Boeing 747, Boeing 767, and McDonnell Douglas MD-11 series airplanes. An HPC module that has incorporated PW SB PW4ENG 72-706, Revision 3, dated July 17, 2000, or earlier Revision, or PW4ENG 72-711, dated June 13, 2000, will have the letters "CB" after the HPC module serial number on the HPC module data plate. 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 (e) 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 Compliance with this AD is required as indicated, unless already done. To prevent a multiple-engine power loss due to HPC surges, which could result in engine power loss at a critical phase of flight such as takeoff or climb, do the following: Number of Cycles until Number of Engines Must Be Limited (a) Limit the number of engines with the HPC CBS configuration to one on each airplane within 100 cycles-in-service (CIS) of the effective date of this AD, or before the cyclic limits defined in the table below, whichever occurs later: Type of airplane Comply by (1) Two-engine. Before 390 cycles-since-new (CSN) or cycles-since-HPC module overhaul (CSO). (2) Three-engine. Before 340 CSN or CSO. (3) Four-engine. Before 305 CSN or CSO. Special Conditions for Installing More Than One HPC CBS Engine on an Airplane (b) Two HPC CBS configuration engines may be used on an airplane only under the following conditions: (1) One engine with an HPC CBS configuration has fewer than 25 CSN or CSO, and (2) The remaining engine has fewer than 615 CSN or CSO, and (3) The airplane is operated for fewer than 25 CIS in this configuration. HPC Modules at HPC Module Overhaul (c) Engines with HPC modules that have been modified to incorporate PW SB PW4ENG 72-706, Revision 3 dated July 17, 2000, or earlier Revision, or SB PW4ENG 72-711, dated June 13, 2000, after the effective date of this AD, are not eligible for installation on an airplane. Definitions (d) For the purposes of this AD, an HPC module overhaul is defined as whenever the HPC stage 12 through 15 blade tip clearances are restored to the clearances specified in the applicable fits and clearances section of the engine manual during the shop visit. Alternative Methods of Compliance (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 (ECO). Operators shall submit their requests 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. Effective Date of This AD (f) This amendment becomes effective on November 9, 2000.