On Sun, 16 Nov 2003 23:11:09 -0600, - Barnyard BOb - wrote:

How about pressing your luck with ALTERNATIVE engine combos?
Got any meaningful data/stats other than BD-5?

In my 2000 database, about 2300 homebuilts are listed as having "AMA/EXPR"
engines. In that year, I show 8 auto-engine powered homebuilts had
accidents. That would be a rate of 0.3%, about a third of the overall
homebuilt rate.

But...we don't know what those "AMA/EXPR" engines actually were. Most were
probably regular 'ol Lycosaurs.

In addition, about 1700 homebuilts were registered with Ford, Chevrolet,
Volkswagen, Mazda, or Subaru engines. If *none* of those "AMA/EXPR"
engines were converted auto engines (which seems unlikely) the auto-engine
accident rate would have been 0.47%, still less than half the homebuilt
rate.

But how accurate is that 8 number for auto-engine-powered accidents in
2000? The NTSB doesn't always say what the engine type is. With a
baseline of only eight accidents one or two additional makes a tremendous
difference.

Looking at the 1990-2003 period, we find 22 accidents where "Subaru" is
mentioned (we'll assume they all refer to an engine installed in the
aircraft, and not the type of car they hit on a forced landing). We'll use
the number of Subaru-powered airplanes in 2003 (429) to compare the results
to the overall homebuilt fleet, the Fly Babies, the BD-5s, and the RV-3s.
Again, this table divides the number of aircraft of accident aircraft
during the 1990-2003 period and divides it by the number of aircraft of
that type registered in January 2003. It's useful for relative
comparisons, but, of course, isn't accurate in an absolute sense.

Accident Rate (total over 14 years)
All Homebuilts 11.1%
Fly Baby 5.7%
BD-5 27.2%
RV-3 8.2%
Subaru-powered 5.1%

By these results, Subaru-powered aircraft had an accident rate less than
half that of the total fleet. But this doesn't include those accidents
where the NTSB online report does not mention the use of a Subaru engine.

Ron Wanttaja