Airworthiness Directives; CFM International, S.A. CFM56-5B1/P; -5B2/P; -5B3/P; -5B3/P1; -5B4/P; -5B4/P1; -5B5/P; -5B6/P; -5B7/P; -5B8/P; -5B9/P; -5B1/3; -5B2/3; -5B3/3; -5B4/3; -5B5/3; -5B6/3; -5B7/3; -5B8/3; -5B9/3; -5B3/3B1; and -5B4/3B1 Turbofan Engines

The FAA is adopting a new airworthiness directive (AD) for CFM International, S.A. CFM56-5B1/P; -5B2/P; -5B3/P; -5B3/P1; -5B4/P; -5B4/ P1; -5B5/P; -5B6/P; -5B7/P; -5B8/P; -5B9/P; -5B1/3; -5B2/3; -5B3/3; - 5B4/3; -5B5/3; -5B6/3; -5B7/3; -5B8/3; -5B9/3; -5B3/3B1; and -5B4/3B1 turbofan engines. This AD requires initial and repetitive eddy current inspections (ECIs) of certain part number (P/N) low-pressure (LP) turbine rear frames. This AD results from a refined lifing analysis by the engine manufacturer that shows the need to identify initial and repetitive inspection thresholds for inspecting certain LP turbine rear frames. We are issuing this AD to detect low-cycle-fatigue cracks in the LP turbine rear frame, which could result in an engine separating from the airplane, causing damage to, and possibly leading to loss of control of the airplane.