TWAL1011727 From United States of America, joined Mar 2006, 597 posts, RR: 0 Reply 1, posted (5 years 4 days 3 hours ago) and read 1708 times:
Not exactly sure but they were checking into a noise and vibration in the left engine..
The last I saw they were pulling the chip detectors.
I guess they found something wrong so they changed the engine.