On Tue, 19 Feb 2008 20:44:57 -0600, Charlie wrote:

If we factor in the reality that Lyc installations are more or less
'standardized', with help almost always available from knowledgeable
predecessors, compared to auto conversions where each is nearly unique,
and we factor in the unpleasant fact (sorry guys) that many of the
people most willing to do an auto conversion are the least qualified to
tackle it, how much should we weight the percentages? Only if you add
the word 'installation' to each category can you reach the conclusion
that Lycs are actually safer, in my opinion.

What do you think?

I understand your logic, but don't agree with it. I look at the powerplant as a
*package*. If the engine itself is more reliable, but it's difficult to achieve
an installation that allows it to show its reliability, I don't feel that it
exonerates the engine as an aircraft powerplant. That's why my statistics
include fuel system problems FWF as an engine-related failure...if all else were
equal, Lycomings and, say, Fords should see the same rate of fuel FWF accidents.
If there's a difference, that means one is more picky as to the quality of the
fuel system install. FWIW, auto-engine conversions seem to have fewer instances
of FWF fuel system problems than certified engines.

The very standardization of the LyConts means that the average builder has a
better chance of achieving a reliable installation.

One has to understand what statistics in these cases really *mean*. The fact
that 25% of aircraft accidents aren't caused by "N" DOESN"T mean that *you* have
a 25% chance of having an accident due to "N". It means, out of 100 owners, 25
of them will suffer that kind of accident. If "N" is due to installation
errors, and you spend extra care on your installation, get advice, use quality
materials, etc., then you are less likely to experience that kind of accident.

BTW, I do track installation errors (I call them "builder errors") in my
analyses.

Ron Wanttaja