Airborne_Again wrote:
The generally accepted figure is that Lycosaurs fail once in 50,000 hours
I have seen such a number also, but it simply cannot be realistic. Maybe it’s a calculated number based on the core engine, perfect operation and perfect maintenance etc. The engine is operated min 20 h every week, 52 weeks per year, perfect oil and fuel delivery, perfect cooling, perfect ignition, runs only at low cruise setting and so on. Maybe then we will see such a number.
In real life, no way. Most engines break down due to not being used for a start, then corrosion, moisture in the oil, vibrations due to bad ignition, detonation, poorly done maintenance, poorly done main overhaul, not operated properly, and the list goes on. Not to mention starting the engine below zero centigrade without preheating. In the old days, when cars used mineral oil, we used to say that starting the car without preheating would add 1000 km to it. True or not, I don’t know, but it certainly is some truth to it. In a Lycoming with different metals in gliding contact, it certainly is not good for the engine, mineral oil or not.
It’s the engine stopping producing power that is interesting, regardless of reason. The real world MTBF for the propulsion system is the only thing that counts.
The 50k is the MTBF. It doesn’t relate to how long the engine will run for. The MTBF of a human has been calculated at something like 500 years (it’s all on the internet) 
in a Cirrus, you would have done the same, but then IF the engine did NOT come back, you’d pull the chute, absent an airport you could glide to. I cannot see what’s wrong with that.
I can’t see much wrong with that either, but that’s not what many are suggesting one should do.
The book by Nate Jaros is good. He posted here previously. His book describes ways of calculating the procedure for doing a forced landing as taught in the military (high key, low key, etc – see e.g. here).
