Most of Mazda engine aircraft crashes are due to bad
plumbing; fuel, water and exhaust.

IIRC, the only one which was actually an internal problem was one guy
who built up his engine without an oil pump, and didn't put enough oil
in his fuel mix.

Keith


I am familiar with that report. I think it was a Coot that
spun in and burned. Engine quit, guy turned back and stalled
due to aft CG. Ken Welter knew the guy well. The NTSB has it all
wrong. I don't know why the engine quit but it was not from a
lack of apex seal oil. The the engine will run for hours without
apex seal oil. I know of one guy that flew from Tennessee to upstate
New York with no oil in the fuel. As far as I know he is still
flying that engine several years later without touching it. Most
people remove the apex seal oil metering pump and mix 2 cycle
oil with the fuel.

As I recall the FAA or NTSB took the engine to  Mazda dealer
that knew nothing about rotaries in aircraft and they
noticed the missing metering pump.

We wrote letters to the NTSB and they just stone walled us on
the subject.
-----------------------------------------

OK here is the report. As I recall the guy was using
a cheap Chinese oil cooler that we had problems with and warned
people about before. He was on the newsletter for awhile but I don't
know if he got the word on that oil cooler. He was the type of guy
that ignored good advice anyway. The oil cooler would split
as soon as the aircraft left the ground, the RPM built up
and the oil pressure built up. Happened twice before to
other people. That of course would pump all the engine oil
overboard in short order. Then the engine bearings would seize.
The company that supplied it no longer sells that oil cooler.

BTW That really doesn't hurt the rotary engine as
one guy did it on the ground. Engine revved to 10,000 RPM and seized
He chiseled the engine apart, replaced the bearings and flew it for
several hundred hours before he crashed it in the woods when trying
to land on an unlighted strip. Walked away from the crash.

I digress.

A piston engine would throw one or more rods. The Mazda requires a
robust oil cooler as the pressure can get to 150 psi when the oil is
cold and the RPM is high enough. Best to use the stock oil cooler
whenever possible.