Originally Posted by
neila83
Frankly I really don't like the idea of someone being on an ETOPS mission, an engine cutting out, and then spending however many hours looking out the window at that one remaining engine, crossing your fingers aware that it has been operating in and out of ash for several days. Isn't the whole point of ETOPS to remove any possible non-independent sources of failure? I don't see how engines operating in these conditions can be ETOPS certifiable, are they going to be doing full detailed inspections after every flight? If they're running normal schedules, impossible surely? I don't know, maybe the engineers can help here.
Indeed! This is exactly the point I was trying to make earlier.
ETOPS certification depends on a documented IFSD rate of less than 0.02 per 1,000 hours. But this exceptional level of reliability was not achieved with engines that were operated in areas of significant volcanic ash exposure for a period of several days or weeks.
The issue I was trying to get at (and that
neila83 has explained) is not whether the ash causes immediate IFSDs - but whether engines operated in this environment have an IFSD rate > 0.02 per 1000 in the coming months.