AD NUMBER: 2008-03-09
MANUFACTURER: CFM International
SUBJECT: Airworthiness Directive 2008-03-09 SUMMARY: The FAA is
adopting a new airworthiness directive (AD) for CFM International,
S.A. CFM56-7B series turbofan engines.
This AD requires revising the Airworthiness Limitations Section
(ALS) inthe Engine Shop Manual (ESM) and the air carrier's approved
continuous airworthiness maintenance program (CAMP) to add
mandatory inspections of certain low pressure turbine rearframes
(TRFs) to the ALS or CAMP.
This AD results from a refined lifing analysis by the engine
manufacturer that shows the need to identify an initial threshold
for inspecting certain TRFs.
We are issuing this AD to prevent failure of the TRF from
low-cycle fatigue cracks. Failure of the TRF could result in engine
separation from the airplane, which could lead to loss of control
of the airplane.