Ed Anderson Wrote:
I loaded up the aircraft the night before for the SERFI trip.  Went out the
next morning and did the preflight.  I noticed that when I pulled the prop
through a couple of turns which I always do, that it seemed a bit harder to
turn than normal.  But, it was our first cold morning having dropped down to
39F that night, So I though it must just be that heavy 50 wt oil being a bit
sluggish.

So I climbed in and started to crank the engine.  With all the injectors so
far away from the intake with that plastic part, its a bit cranky about
starting on cold mornings (will move two of them back to the block).  So, it
will catch run a bit and stop until there is sufficient fuel vapor to keep
her turning.  Might take me 2-3 attempts on a cold morning.

Anyhow it caught the first time and ran for probably 5 seconds, noticed the
oil pressure had come  up  then the engine died.  When I attempted to crank
it the second time, it just sort of did a slow motion moan and I noticed the
batter voltage dropping to 4-6 volts (brand new battery), so I knew
something was wrong.

Switched everything off and got out to inspect.  I found the prop exceeding
difficult to turn over at this point.  There were clearly two
possibilities - gearbox or engine.  I noticed that the normal 3/8" gear lash
free play at the end of the prop was not there - or rather the prop could be
moved that distance but it was very stiff and resisting.  So that told me it
was likely a gear box problem.

I first thought perhaps oil starvation of the gearbox bearings, but when I
removed the oil drain over 1/4 cup drained out - normal amount.  So that
didn't seem to be the problem.
I contacted Tracy and we decided to ship it back to him.  As you know his
casing is in two parts, well the first part (prop shaft) came off first and
I noticed that the prop flange would not budge, so that told me the problem
was in the front part of the gear box containing the prop shaft.  I
inspected the planetary and sun gears, etc and no indication of any problem.
So shipped the front casing and prop shaft to Tracy.

Upon examination, Tracy found that when I had the unit nickel plated, some
of the plating got on the bronze bearing sleeve.  The nickel coating (if you
recall) has a golden tone to it and I did not detect it on the bronze
bearing when I inspected it before reassembling it. The bearing was supposed
to be protected from the plating solution - but clearly some got through and
I didn't catch it.

 The plating had proceed to flake off of the bronze and while most of it
apparently went into the sump with no problem, some of it got "smeared" into
the bronze bearing.  As more of the nickel built up there it reduced the
rather small clearance between shaft and bronze bearing until it finally
caused the shaft to stop or rather become very difficult to turn.  It
apparently had not yet seized although it was well on its way to doing so in
another few revolutions.

Tracy reported that because I had caught it so early that there was no
damage to the gearbox or shaft.  He bored the bronze cylinder bearing enough
to clean off any remaining plating and shipped it back.  Flew it yesterday
with no problem.

So there was no problem with Tracy's gear box, design, components or
assembly - just my failure to detect the plating where it shouldn't have
been.  Interestingly enough, it appears to have no problem adhering to the
aluminum - just not to the bronze sleeve.

So looks like I'll get to fly to Shady Bend instead of drive.

Best Regards

Ed

 
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