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ACRO E-mail Archive Thread: oil pressure problem



                


Thread: oil pressure problem

Message: oil pressure problem

Follow-Up To: ACRO Email list (for List Members only)

From: "Dr. Guenther Eichhorn" <gei at head-cfa.harvard.edu>

Date: Fri, 29 Sep 1995 16:40:01 UTC


Message:

  
Hi,

I was asked to post a more precise account of what is going
on, so here it is:
Symptoms:
1. The oil pressure is OK in level flight when the engine is
cold.  I don't know how it is in aerobatics flight with a
cold engine, because I don't do that.
2. The oil pressure is about 65 psi when the engine is hot in
level flight and in inverted flight.  It is very twitchy.  It
jumps up and down by 10 - 15 psi.
3.  When I do aerobatics (advanced sequences with both
positive and negative g's), every once in a while the oil
pressure drops to zero long enough for the prop to go to low
RPM.  This happens about once every two or three sequences. 
As soon as I stabilize the airplane, the oil pressure is back
to its twitchy self around 60 psi or so.  It does not happen
in the same place in the sequence.  It has happenend after
the outside part of the inside-outside 8, on the downline of
a humpty after a roll, etc.

What have I done so far?
Maybe a better question is "what haven't I done".
1.  I have had the engine repaired (not a complete major
overhaul, but close to it, new bearings, pistons, valves,
oil pump, etc).
2.  Replace the Christen valve and all the hoses to and from
this valve.
3.  Re-configured the inverted system to the S-2B
configuration, where the air/oil separator line is separate
from the inverted oil pickup line.
4.  About a year ago, the prop governor was overhauled.

The current problem is new.  Before the whole problem
started, I just had low oil pressure (around 40 psi), but it
was stable.  After replacing all the hoses to the inverted
system and the Christen valve, the oil pressure was high
enough, but fluctuating.

Guenther
| Guenther Eichhorn | gei at cfa.harvard.edu | Flying is the Pitts
| http://acro.aerobaticsweb.org/iac_homepg.html




                


© Dr. Günther Eichhorn
Retired
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