AD NUMBER: 2018-09-51

PRODUCT: CFM International, S.A., (CFM) CFM56-7B model engines.

ACTION: Final rule; request for comments.

SUMMARY:  This emergency AD was sent previously to all known U.S. owners and operators of CFM CFM56-7B model engines.

This AD requires a one-time ultrasonic inspection (USI) of the concave and convex sides of the fan blade dovetail.

This AD was prompted by a recent engine failure due to a fractured fan blade, which resulted in the engine inlet cowl disintegrating and debris penetrating the fuselage, causing a loss of pressurization, and prompting an emergency descent.

DATES: This AD is effective June 7, 2018 to all persons except those persons to whom it was made immediately effective by Emergency AD 2018-09-51, issued on April 20, 2018, which contained the requirements of this amendment. Comments must be received by July 9, 2018.

COST: The FAA estimates that this AD affects 532 engines installed on airplanes of U.S. registry. The cost of compliance is estimated as follows:

• Inspect engine fan blade - $170 per engine for two hours labor.
• Replace fan blade - $8,585 per engine for parts and labor.

FMI: AD