Transport Canada and the FAA have issued emergency airworthiness directives requiring immediate replacement of certain turbine blades in Pratt & Whitney Canada (P&WC) PT6 engines.

Transport Canada, the engine design authority, issued emergency airworthiness directive (AD) CF-2024-05 on Feb. 16, requiring the removal “prior to next flight” of affected second-stage power turbine (PT2) blades in PT6A/E-60 series turboprop engines. The FAA issued supporting AD 2024-04-51 the same day.

The directives followed a report of an in-service PT2 blade failure on a PT6A-67 engine. There also have been two other events of PT2 blade failures during testing at the manufacturer’s facility, Transport Canada said. The blade failures in all cases were contained.

The PT6A-67 engine powers the Beech Starship. Some of the other engine models covered in the directives power aircraft including the Socata TBM 700, Piaggio Avanti, TBM 850, Air Tractor AT-802AF, and Daher TBM 960.

While P&WC was still investigating the root cause of the blade failures “preliminary investigation determined that the power turbine modules in all event engines contained newly manufactured Part Number (P/N) 3056693-01 blades from the same raw material,” Transport Canada said.

The directives require the removal and replacement of PT2 blades with serial numbers listed in a P&WC Alert Service Bulletin.

In a statement provided to BCA, P&WC said it has recently identified “a limited subpopulation of high-power PT6A and PT6E engines” that require a part replacement before returning to service.

“The population is limited to engine parts with less than 50 flight hours (total, or since last shop visit, or total time since second stage power turbine repair) manufactured from a single batch of sourced product (this is not powder metal-related),” the manufacturer said. “Pratt & Whitney Canada is working with airframers, operators and Transport Canada to issue fleet instructions and to schedule maintenance.”

The ADs apply to the following engine models: PT6A-64, PT6A-66, PT6A-66A, PT6A-66B, PT6A-66D, PT6A-66T, PT6A-67, PT6A-67A, PT6A-67AF, PT6A-67AG, PT6A-67B, PT6A-67D, PT6A-67F, PT6A-67P, PT6A-67R, PT6A-67RM, PT6A-67T, PT6A-68, PT6A-68B, PT6A-68C, PT6A-68D, PT6A-68T, PT6E-67XP, and PT6E-66XT.