Emergency Airworthiness Directive Issued for New Pratt & Whitney Canada PT6 Power Turbine Blades

Transport Canada has enacted an emergency Airworthiness Directive (AD) CF-2024-05, targeting a significant number of Pratt & Whitney Canada (P&WC) PT6 turbine engines. This directive necessitates immediate compliance through the removal of specified PT2 (power turbine) blades prior to any subsequent flights.

The directive is issued in response to a recent in-service incident involving a PT2 blade failure on a PT6A-67 engine, alongside two additional failures during manufacturer testing. These incidents, although contained, underscore the potential risk associated with the affected blades.

Investigations by P&WC into these failures have revealed that the newly manufactured blades, identifiable by part number 3056693-01, originate from a singular batch of raw material. Notably, these components have logged fewer than 25 hours of air time since their initial deployment. The directive highlights the critical nature of this issue, stating, "Failure of PT2 blades could precipitate engine power loss or necessitate in-flight shutdown, thereby compromising aircraft control." An aborted takeoff was reported as a direct consequence of one such failure.

The AD specifies the serial numbers of the blades in question, which, in addition to being newly manufactured, have accrued less than 50 hours of air time post-manufacture, subsequent to a shop visit, or following a second-stage power turbine repair. It is mandated that these blades be extracted and decommissioned.

P&WC has identified a specific subset of high-power PT6A and PT6E engines necessitating part replacement prior to return to service. This subset is confined to parts with fewer than 50 flight hours, derived from a single batch of sourced product. Collaborative efforts with airframers, operators, and Transport Canada are underway to facilitate fleet instructions and maintenance scheduling. The company has clarified that the issue is not related to powder-metal components.

The timeline for blade replacement is projected to range from one to four weeks. Accessibility to overhaul facilities will significantly influence this duration; operators with limited access may experience the longer end of this spectrum, whereas those with shop access can expect a turnaround in under a week.

Approximately 5,000 blades, fabricated from the implicated raw material, are subject to this directive. Each PT6 engine incorporates 43 blades on its second turbine disk, though individual engines may feature blades from diverse raw material sources (co-mingled inventory).

The directive encompasses a wide array of engine models, including PT6A-64, PT6A-66, PT6A-66A, through to PT6E-66XT, underscoring the broad impact and importance of compliance to ensure aviation safety.