Summary
The FAA proposes to adopt a new airworthiness directive (AD) for CFM International, S.A. CFM56-7B series turbofan engines. This proposed AD would require initial and repetitive eddy current inspections (ECIs) of certain part number (P/N) low-pressure (LP) turbine rear frames. This proposed AD results from a refined life analysis by the engine manufacturer that shows the need to identify an initial and repetitive inspection threshold for inspecting certain LP turbine rear frames. We are proposing this AD to prevent failure of the LP turbine rear frame from low-cycle-fatigue cracks. Failure of the LP turbine rear frame could result in engine separation from the airplane, possibly leading to loss of control of the airplane.