Hey Paul, just spotted the post.
For serious answers - hope this helps:
Engine Failure Statistics
2 percent are internal failures sometimes detectable by oil analysis
2 percent are oil problems related to pumps, filters or lines.
3 percent are induction problems related to hoses, clogging or alternate air doors
5 percent are spark problems related to spark plugs, magnetos, wiring harness, or switches.
6 percent are related to poor maintenance
7 percent are due to cylinder/valve problems due to improper leaning
8 percent are fuel related problems of selectors, carburetors, primers, or pumps.
8 percent are carburetor ice related where application of heat occurs too late to be effective.
11 percent are from contaminated fuel
20 percent are from starvation, exhaustion or other failure to deliver problems.
28 percent of engine failures are for unknown reasons where fuel, air or spark are responsible.
Pilots are in the main most likely to be responsible for an engine failure.
Engine component failure accidents:
1.
Lycoming engines fail twice as often as Continental2. Engine size has no effect of frequency of failure
3. 43% mechanical
4. 1 in 5 accidents during cruise. Cruise flight accidents due to weather and fuel.
5. 1 in 3 engine/prop
6. 1 in 4 due to gear or brakes
7. 1 in 6 due to fuel
Fuel exhaustion is most common factor.
8. 18% of engine type accidents caused by engine failure unrelated to pilot induced failure.
9. 1.296 per 100,000 flight hours
10. Pneumatic system is 1:40,000 IFR flight plans filed.
11. 25% of all accident occur after partial or total loss of engine power.
12. When planes switched from piston-powered engines to jet engines in the 1960s, they immediately became more reliable by a factor of 10.
Other reasons: UFO attack
Flying into restricted airspace (Military patrolled)
[glb]Thanx. Carl[/glb]
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.....(In the nicest possible way).... 
