I once my gearbox freeze up as well,
Chris.
But, it was very clear the culprit –
I had the housing nickel plated and while I made it very clear to the plating
shop that the inner race of the bronze pressure bearing was to be protected and
not plated – well, I think you can guess what happened.
It turns out this process produces a light
gold/tan color and when I visually examined the bearing it looked fine.
Buttoned it back up and flew for 10 hours. Went out one Cold morning
to go to fly in and pulled the prop through as I normally did. It
felt a bit stiff, but it was a cold morning, so I hopped in threw a few switches
and fire up the engine – it ran for approx 10 seconds before dying.
Somewhat surprised (but, it was a cold
morning), I try to crank it again, all I got for my effort was a groan from the
engine and notice my volt meter go from 12.5 volts to approx 6 volts – I immediately
ceased my attempt to start the engine. Unbuckled and climbed out. Went to
the prop and tried to pull it through and could barely budge it with
considerable force.
Sent it to Tracy, and he found that nickel
plating had come lose from the bronze bearing and had basically packed up the
bearing and took up the clearance between shaft and bore. Tracy bored out the
bronze bearing a few fraction of a thousands and it was good as new.
You are right - the front bearing does not
rely on engine oil for lubrication but is permanently lubricated. The
bronze bearing is pressure fed from the engine – mine gets approx 80
PSI. If you are in doubt about your PSRU engine fed lubrication, take off
the drain and hook up a hose to end (secure it well so it can’t get into
the prop and run the hose into a container). Start your engine and run it
for approx 30 sec. shut it down and go measure the amount of oil in your
container, you should find at least a pint. With the old Ross Redrive
with a pressure restrictor I could get a pint in 60 seconds.
OR if you feel comfortable with it –
don’t bother, I never checked it on Tracy’s
drive but had on the Ross because I knew some units had marginal lubrication –
and that is the reason I ditched the Ross after about 160 hours the sun gear
start galling from lack of adequate lubrication. With Tracy’s unit being fed full engine oil
pressure (no restrictor) I don’t have that concern. But, if for any
reason you do have a question about your lubrication flow you could do this
check.
Ed
From: Rotary motors in
aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of Chris Barber
Sent: Monday, February 15, 2010
2:34 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] PSRU oiling
question
I just received my PSRU back
from Tracy.
If I understand his explanation correctly my prop shaft bearing at the end near
the prop (pusher) bound up somehow. He machined it, made other needed
adjustments (?) and sent it back to me very promptly...bout a week turn around
(of course I dropped a bit on overnight shipping to make sure he got it
before he was off again <g>).
The problem may have been due to a
couple of factors....not really sure, but I discovered it after my plane was
sitting out of the hangar due to roof repairs for about 6 or 7 weeks.
When I went up to start it to taxi back to the hangar, I pulled the prop through
a few times by hand and all seemed fine. I started it up, started, was
tickled, but it it stalled. Did I mention it was REALLY cold for Houston...about 27
degrees. I started it again and is sounded "labored" and was
running poorly. It was about 1:00 am (I had just gotten off duty), so I
figured I call it a night. I got out and turned the prop through again
and could barely turn the prop. Damn. I thought I toasted another engine.
Damn.
A couple of days later a friend and I
pushed the plane back to the hangar and I walked away from the issue for a
couple of weeks. Went so far as to even looking at financing a Lyc
<shudder>. I distracted myself by doing some interior work and
wiring...actually got my radios far enough along to listen to ATIS for a
few minutes...on the bench.
Finally, two days after my recent loss,
I forced myself to the hangar and pulled the PSRU. I had already looked
inside the exhaust ports and the chambers looked clean and smooth. I had
also drained the oil, with a magnet (I know, some is aluminum) in the drain
filter and found it all to be perfectly clean. Well, without
the PSRU the engine turned perfectly making that sweet churning sound
through the open spark plug holes.
I turned to the PSRU. I took
out each section slooooowly. No signs of binding, chipping or any other
damage in each part....until I got to the last section, the sealed section by
the prop. The prop hub would not turn. I could barely turn it with
the prop on. Without the prop is was a no go. So, I sent it to Tracy.
ANYWAY, now that I have it back mounted
on the bird I am curious as to the oil going into the system. Even
though I went through this long explanation, I only have a questions about
the oil entering the PSRU. There is no reason to suspect any oiling
issues caused the previous problem...I just like to share on occasion.
However, last night when I was hooking up everything I decided to pour
some oil directly into the in oil hole on top of the PSRU. My
curiosity is that it just kinda set there and very slowly seemed to seep
into the PSRU. Does oil pressure forced it into the PSRU, thus getting
more oil in. I would think with everything spinning etc under power
the oil flow etc would be much more dynamic, thus providing a more significant
lubricating event. I don't really know what I was expecting. my oil
flow seems good. It just got me thinking and wanting to have a better
understanding. TIA
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