A few days ago, I read an article speculating on the cause of the CFM engine failures - I can't remember the source but it was by a former pilot and I found it cogent.
These engines are old, and very widely used. The author suggested it was metal fatigue in the turbofan which wasn't caught - microcracks are hard to find, but can cause structural failures at operational velocity. Southwest's engine overhaul regime for this engine is every 10 000 miles, but that will probably need to be reduced pending the results of the investigations.
10,000 miles? That seems like way too often for an "engine overhaul".
For example, Southwest 1380 (this recent flight) was a New York to Dallas trip, 1264 nautical miles (roughly). That means an "engine overhaul" (and I'm not sure exactly what that entails) would be required after just eight of these flights -- or, say, four round trips -- and possibly even seven if it's 10,000 statute miles. I'm not a pilot or jet engine mechanic but that seems a bit too frequent.
If that standard is specific to this engine because of its age or history of issues or something (and "regular" engines have a much lower standard), that would make more sense.
You are correct:10,000 miles is ridiculously low, that was off the top of my head and wrong. I should have said the SW 1380 plane had 10,000 flights logged since its last engine overhaul before the accident[1] - the article doesn't say how long the intervals are (but they are >10,000 flights).
These engines are old, and very widely used. The author suggested it was metal fatigue in the turbofan which wasn't caught - microcracks are hard to find, but can cause structural failures at operational velocity. Southwest's engine overhaul regime for this engine is every 10 000 miles, but that will probably need to be reduced pending the results of the investigations.