AD 2021-14-13 Prompted By A Report Of An Uncontained Engine Failure Resulting From Cracks In The Knife Edge Of The HPT

The FAA is adopting a new airworthiness directive (AD) for all Pratt & Whitney (PW) PW2037, PW2037M, PW2040, and F117-PW-100 model turbofan engines.

This AD was prompted by a report of an uncontained engine failure resulting from cracks in the knife edge of the highpressure turbine (HPT) 2nd-stage air seal assembly. This AD requires fluorescent penetrant inspections (FPIs) and visual inspections of the HPT 2nd-stage air seal assembly and, depending on the results of the inspections, replacement of the HPT 2nd-stage air seal assembly with a part eligible for installation. This AD also requires replacement of the affected HPT 2nd-stage air seal assembly, depending on the engine model, at either the next engine shop visit or the next piece-part opportunity. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective September 1, 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 PW2037, PW2037M, PW2040, and F117-PW-100 model turbofan engines. The NPRM published in the Federal Register on June 1, 2020 (85 FR 33043). The NPRM was prompted by a report of an uncontained engine failure resulting from cracks in the knife edge of the HPT 2nd-stage air seal assembly. After further analysis, it was determined that the knife-edge crack was due to seal rubbing that elevated the HPT 2nd-stage air seal assembly temperature and induced fatigue. In the NPRM, the FAA proposed to require initial and repetitive borescope inspections (BSIs), FPIs, and visual inspections of the HPT 2nd-stage air seal assembly and, depending on the results of the inspections, replacement of the HPT 2nd-stage air seal assembly with a part eligible for installation. The NPRM also proposed to require replacement of the affected HPT 2nd-stage air seal assembly, depending on the engine model, at either the next engine shop visit or the next piece-part opportunity. The FAA is issuing this AD to address the unsafe condition on these products.

FMI: www.regulations.gov