AD FAA-2012-1005

We are adopting a new airworthiness directive (AD) for certain Pratt & Whitney Canada Corp. (P&WC) PT6C-67C turboshaft engines. This AD requires initial and repetitive borescope inspections to verify the presence of a retaining ring securing the power turbine (PT) baffle located near the second stage PT disk. If the engine fails the inspection, this AD also requires removing the engine from service before further flight. This AD was prompted by five reported incidents of second stage PT disk damage. We are issuing this AD to prevent damage to the PT disk which, if undetected, could cause uncontained PT disk failure and loss of control of the helicopter.