19 February 2024
An Airworthiness Directive has hit Pratt & Whitney Canada’s signature turboprop engine, the PT-6, previously considered to be ‘bomb proof’.
The PT6 has been in continuous production since it entered service 60 years ago, and is used across a range of types of aircraft including the TBM 960, Pilatus PC-12, Cessna Caravan, Beechcraft King Air and, in turboshaft configuration, many helicopters.
The Airworthiness Directive (AD), issued by Transport Canada, affects engines fitted with newly manufactured Second Stage Power Turbine (PT2) blades. The AD mandates removal of the suspect blades prior to next flight.
It follows one in-service report of PT2 blade failure and two failures during tests.
The AD says: “P&WC is still investigating the root cause of the blade failures, but 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.
“In all cases, the blades had accumulated less than 25 hours air time since new.
“Failure of PT2 blades could lead to engine power loss or in-flight shut down, potentially resulting in reduced control of the aeroplane.”
The AD has been passed on by the UK CAA and can be downloaded here.
