Originally Posted by
tdracer
There are differences between the fans of the different marks of the CFM56 (the 737 NG is the -7, previous 737s were -3, the A320 is -5, and those used to re-engine KC-135s and DC-8s were the -2). Furthermore, according to one write-up, the event engine had 40,000 cycles, 10,000 since overhaul (I'm a bit suspicious - 40k cycles would be a huge amount - I wonder if that's hours not cycles). At any rate it's a very high time engine, so it seems likely that we're looking at a wear-out mode - which may be unique to the CFM56-7 model.
At any rate the FAA has some explaining to do regarding why it's been sitting on a planned fan blade inspection AD for 8 months...
It appears the fan blades can be removed from the disc without greatly dismantling the engine while on the wing, can the blades be crack checked this way.