PPRUNE:
Thanks for that - I had missed FAR 135.415. Wonder what happens to the data that is collected, is it published on the FAA Incident Database?
As a matter of interest how many FSDOs look after the GOM? (As all reports have to go to the the FSDO, do they collate regionally?)
Shawn:
From memory the acceptable engine-failure rate for ETOPS is 1x10 -8 (1:100,000,000) and for the second engine 0.3x10 -8 (0.3:100,000,000) per flight hour.
You mentioned earlier that you would accept the SEIMC rate; this is proposed by the ICAO WG for 'very reliable engines' to be 1x10 -5 (1:100,000) per flight hour.
PPRUNE indicates that engine failures are required by FARs to be reported for CAT operations. In Europe, in most States, this is also the case (in the UK turbine failures have to be reported under the Mandatory Occurance Report system).
As for the causes of failure; examination of the evidence (from Europe at least) appears to indicate that the core engine (I won't qualify that as the clever engineers will have a field day) has a failure rate of about 0.2 to 0.5x10 -5 (0.2 - 0.5:100,000) per flight hour.
Yes, as expected, maintenance failures add to that rate as do operational conditions. What do I mean by operational conditions: well in once again in Europe, air pollution appears to cause pitting of the lining or compressor blades which eventually leads to compressor failures (this can be offset by coating the blades and by periodic - splitting the engine - inspections); hot end failures caused mainly by abuse - be it hot starts or exceeding the limits during take-of manouevres (which can be offset by fitting Usage Monitoring System - not HUMS, which is mainly concerned with vibration monitoring - but plain usage in the sense of event parameters).
The combined effect of core engine-failures, maintentance events and operational events take the engine failure rate close to 1x10 -4 (1:10,000). With mitigation - coating the blades, inspection and fitting the UMS (which by the way eliminates hot starts), the rate settles at or slightly above 1x10 -5 (1:100,000) - probably as good as we can achieve given human factors.
The question of surviving the engine-failure is really down to the place where it occurs and includes: the autorotation - which comprises the two factors of environmental conditions and skill; and surviving the time to rescue - which is down to the clothing, and survival equipment (lifejackets, liferafts, survival packs etc).
Finally
Are we still happy with single-engine single pilot operations at night (and when the conditions do not support a safe outcome) with a failure rate of 1:10,000 flight hours?
Not me!
Mind you if you are flying a twin in Class 3 the probability of an engine failure leading to a ditching becomes 1:5,000 at worst and 1:50,000 at best.
Why not check out FTW03FA118 and see if you think those conditions were acceptable.
Last edited by Another KOS; 8th Jun 2003 at 22:57.