Airworthiness Directive · Amendment 39-11947 · Pratt & Whitney PW4000 Series Turbofan Engines
Pratt & Whitney PW4000 Series Turbofan Engines
Superseded. A later AD replaced this one: AD 2001-15-12. Comply with the one in force.
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.
This amendment adopts a new airworthiness directive (AD) that is applicable to certain Pratt & Whitney (PW) PW4000 series turbofan engines that are equipped with the high pressure compressor (HPC) cutback stator (CBS) configuration and that are used on Boeing 747, Boeing 767, and McDonnell Douglas MD-11 series airplanes. This action requires Operators to limit the number of engines with the HPC CBS configuration to one per airplane, and prohibits installation of engines with HPC modules modified after the effective date of this AD to incorporate the HPC CBS configuration. This amendment is prompted by reports of HPC surges in engines that have the HPC CBS configuration. The actions specified in this AD are intended 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.
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:
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. |
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.
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.
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.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
