12
We where having serious oil problems the last few times Dan flew it.
The last flight we lost a full gallon and a half over board. Despite
that it took only 1 minute 47 seconds to get to 10k and best the
record.

The oil pressure started at about 120 psi and by the time Dan got to
10,000 feet it was down to 50 psi. As soon as he leveled off it rose
back to 120 psi. I suspected pump caviatation as the intake was
about 3 feet below the oil pressure pump when the airplane had a 45
degree nose pitch up angle.

The two problems were not necessarily related.

One of the fittings on the tank, being used for the vent line, had
damaged threads. Somebody cut the vent hose fitting nut down to
compensate. That was a new trick on me. No matter your age and
experience there is always something  new to learn :-)

It worked as long as it was tight but it did not take much to loosen
it. I believe thats how we got a half gallon of oil in the bottom of
the fuselage :-)

It just so happened I had a steel -12 AN fitting so I screwed that
on and it cleaned up the aluminum threads.

It is 1" & 5/16" by 12 threads per inch which just so happens to be
the same size nut that holds the wheels on a tractor trailer truck
:-)

You can get steel dies in that size but  they cost over $50.

Paul Lamar

Paul,  Hydraulics are a real problem if the suction hose is undersized.
Years ago when building Ag tractors it was specified that I Install a 2
inch suction hose and also a header tank to prevent cavitation. There
are a few options but all involve alterations which are time consuming
and the cost involved.   Good luck as usual,

Neil Unger. In Oz

Neil owns a 650 HP tractor about the size of a house :-)
He should know.

Thanks Neil.

Paul Lamar

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