Originally Posted by IO540
mechanical failure accounts for less than 15% of fatal IFR accidents. Of those, about half of them will be vacuum and electric system failures, a quarter fuel exhaustion and a quarter mechanical engine failures
So, 1/4 of 15% i.e. 4% of fatal IFR accidents is engine failure.
I'm not sure that's the whole story. Bear in mind that these are flight under IFR, including those in CAVOK conditions. If you look at flights with, for example, ceilings less than 500 ft or visibilities less than 1 mile, they might tell a different story.
I recall, while I was flying SE IFR regularly, checking out the NTSB site to find engine-failure-related fatal accidents to prove just how safe SE over low ceilings and poor visibilities is. I stopped after finding an uncomfortable number.
I don't believe that SE over low ceilings and poor visibilities is an
unacceptable risk, particularly with dual vacuum and dual electrics as some singles have. But I do think it's an
increased risk, nontheless.