When one pores over the number of accident reports I have over the years, a few things stand out. One is there are a lot of engine failures resulting in the NTSB’s definition of an accident. Another is that post-accident investigation frequently fails to identify a reason for the failure; the engine runs fine when tested later. And we have to remember that many engine failures are not reported when there’s no substantial damage or serious injury.
In other words, the reasons for many engine failures can be hard to nail down, and there are far more of them than make the NTSB data base—pilots often either resolve the problem while airborne or get back on the ground without damage or injury.
