Summary
The FAA proposes to supersede an existing airworthiness directive (AD) for General Electric Company (GE) CT7-5A2, -5A3, -7A, - 7A1, -9B, -9B1, and -9B2 turboprop engines, with certain part number (P/N) and serial number stage 2 turbine aft cooling plates installed. That AD currently requires a onetime eddy current inspection (ECI) of boltholes in certain P/N stage 2 turbine aft cooling plates. This proposed AD would expand the population of affected CT7 turboprop engine models, but would reduce the number of cooling plates affected. It would also require a onetime ECI of boltholes in certain P/N stage 2 turbine aft cooling plates. This proposed AD results from the manufacturer identifying the affected stage 2 turbine aft cooling plates by serial number. We are proposing this AD to prevent separation of the stage 2 turbine aft cooling plate, resulting in uncontained engine failure and damage to the airplane.