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<< Lancair Builders' Mail List >>
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Angier Ames,
Perhaps I can help you decide what to do about your new engine break-in
problem. At least I can relate my experience with the same problem and tell
you how it came out.
I heard the same cautions as you have prior to my initial start-up of my new
O-320D1F. You must run at max power for the first two hours etc., etc.. I
believe that there is some substance to these precautions and I would
suggest that you get the straight story directly from Lycoming. So, how do
you do that with I new experimental aircraft that needs to be thoroughly
ground tested and taxi tested prior to the first flight?
This is what I did. At the first start-up I tied a rope to the tail
tie-down and the other end to my pick-up truck. I didn't yet trust the
brakes at high power. I ran the engine through a range of power settings,
checking the hydraulic, constant speed prop and function of other
instruments. Then I ran the engine up to max. power for about 5 minutes,
back to about 1700 RPM for about 2 minutes and back to max power until the
CHT was approaching the red line. I was watching the CHT on all 4 cylinders
the whole time because you don't have sufficient cooling air on the ground.
Then I shut down and let her cool down. I repeated this procedure a couple
of more times and then did some taxi testing. Of course the high speed taxi
test were done with full power applied while watching RPM to verify max. RPM
on T. O. roll. By the time that I was ready for the first flight, I had
about 2.5 hours on the engine.
The results of my non-conventional break-in are as follows. Engine has been
running fine for 260 hours. Oil consumption is about 1 quart in 30 hours.
Since I usually change oil after about 30 to 40 hours, frequently, I don't
have to add any between changes. I believe that the rings/cylinders have
been broken-in OK. Don't you?
There is on thing that I would recommend, that I did not do was to make sure
that there was no loose rocks etc. in front and under the prop that would
be picked up and damage your prop. When I finished my high power run-ups I
had a few paint chips taken out of my brand new MT prop. Just hose down or
sweep the area in front of the prop. The time period that you can run your
engine on the ground before reaching red line is of course affected by OAT.
Winter is the best time because you can run longer.
Bob Jude
N65BJ
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