E-AD 2024-04-51: MCAI States That There Has Been A Recent In-Service Report Of A PT2 Blade Failure

The venerable PT-6 has had some recent issues... resulting in an Emergency AD.

This emergency AD was prompted by reports of second-stage power turbine (PT2) blade failures. Transport Canada, which is the aviation authority for Canada, has issued Transport Canada Emergency AD CF-2024-05, dated February 15, 2024 (Transport Canada Emergency AD CF-2024-05) (referred to after this as the mandatory continuing airworthiness information, or the MCAI), to correct an unsafe condition on Pratt & Whitney Canada Corp. (P&WC) Model 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 engines. The MCAI states that there has been a recent in-service report of a PT2 blade failure on a model PT6A-67 engine and two reports of PT2 blade failures during testing at the manufacturer’s facility. The PT2 blade failures were contained. The manufacturer is investigating the root cause of the PT2 blade failures, but the preliminary investigation determined that the affected power turbine modules contained PT2 blades with part number 3056693-01, which were newly manufactured from the same raw material. 

In all cases, the PT2 blades had accumulated less than 25 hours air time since new. Transport Canada Emergency AD CF-2024-05 specifies removal of the suspect blades prior to the next flight and prohibits installation of the suspect blades. Transport Canada Emergency AD CF-2024-05 states that the corrective actions are interim actions until the root cause investigation is completed. This emergency AD is intended to prevent the failure of PT2 blades. This condition, if not addressed, could result in engine power loss or engine in-flight shut down, resulting in consequent emergency landing or reduced control of the airplane.

This product has been approved by the aviation authority of another country and is approved for operation in the United States. Pursuant to the FAA’s bilateral agreement with this State of Design Authority, it has notified the FAA of the unsafe condition described in the MCAI and service information described above. The FAA is issuing this emergency AD after determining that the unsafe condition described previously is likely to exist or develop in other products of the same type design.

FMI: www.regulations.gov