AD 2020-25-09 Prompted By Reports Of Damaged Or Failed 3rd Stage LPT Duct Segments

The FAA is adopting a new airworthiness directive (AD) for all Pratt & Whitney Division (PW) PW4164, PW4164-1D, PW4168, PW4168-1D, PW4168A, PW4168A-1D, and PW4170 model turbofan engines with a certain outer combustion chamber assembly and 3rd stage low-pressure turbine (LPT) duct segments installed.

This AD was prompted by reports of damaged or failed 3rd stage LPT duct segments on PW engines with the Talon IIB outer combustion chamber assembly configuration installed. This AD requires removing and replacing certain 3rd stage LPT duct segments. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective January 14, 2021.

Supplementary Information: The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to all PW PW4164, PW4164-1D, PW4168, PW4168-1D, PW4168A, PW4168A-1D, and PW4170 model turbofan engines with a certain outer combustion chamber assembly and 3rd stage LPT duct segments installed. The NPRM published in the Federal Register on June 12, 2020 (85 FR 35812). The NPRM was prompted by multiple reports of damaged or failed 3rd stage LPT duct segments that resulted in engine surges, in-flight shutdowns, diversions, and air turnbacks. The reports were attributed to elevated gas path temperature at the outer diameter of the turbine flowpath and high-pressure turbine (HPT) 2nd stage blade outer air seal spallation, which led to the distortion and liberation of 3rd stage LPT duct segments. In the NPRM, the FAA proposed to require removing and replacing certain 3rd stage LPT duct segments. The FAA is issuing this AD to address the unsafe condition on these products.

FMI: www.regulations.gov