There was an article in the February 2011 issue of Kitplanes titled, "Safety is no Accident", by Ron Wanttaja.  In light of the recent flexplate failures, I found it interesting that it highlights two areas where automotive engines tend to fail, the cooling system and the gear reduction unit.  To quote, "Note that auto conversions have a higher accident rate right where you would expect it--in engine cooling and in the systems that convert engine power to a slower speed for a propeller or helicopter rotor."  Seems that we've hit on one of the primary failure modes here.  According to Ron's calculations, the accident rate for auto engine homebuilts was 23% higher than for homebuilts with traditional engines.  The rotary had the fewest total accidents, but the rotary also has the fewest number of a/c flying.  This is a well written article that should be on everyone's reading list. 

 

Note:  Mr. Wanttaja is a systems engineer, engaged in satellite orbit/constellation design and analysis, launch vehicle and onboard propulsion system trades, and operations concepts for space systems.  He worked on the early design studies for the International Space Station. 

 

Mark