Airworthiness Directives; Pratt and Whitney PW4000 Series Turbofan Engines

This amendment supersedes two airworthiness directives (AD's), 2000-22-01 and 2001-09-07, that both apply to Pratt and Whitney (PW) model PW4000 series turbofan engines. AD 2000-22-01 requires that operators limit the number of PW4000 engines equipped with the high pressure compressors (HPC) in the cutback stator (CBS) configuration to no more than one engine on each airplane, and prohibits the installation of engines with HPC modules in the CBS configuration after the effective date of that AD. AD 2001-09-07 requires that operators limit the number of engines with potentially reduced stability to no more than one engine on each airplane, and remove those engines before exceeding certain cyclic limits. Reports of HPC surges in PW4000 engines that have the HPC in the CBS configuration prompted those AD's. This Amendment will limit the number of PW4000 engines with potentially reduced stability on each airplane by applying rules based on airplane and engine configuration, and require that engines that exceed HPC compressor cyclic limits based on cycles-since-overhaul (CSO) are removed from service. This AD will also limit the number of engines with HPC CBS configuration to one on each airplane, and will establish a minimum rebuild standard for engines that are returned to service. This Amendment is prompted by further analyses of compressor surges in PW4000 engines. The actions specified by this AD are intended to prevent multiple-engine power losses due to high pressure compressor (HPC) surge and to reduce the rate of single-engine surge events.