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Date: Sat, 18 Sep 2010 21:40:00 -0500
Message-ID: <AANLkTims4MDNBC0fMqo981fvqZVNdke7PN6sGvc46HTB@mail.gmail.com>
Subject: Watch that psru oil seal
From: Mark Steitle <msteitle@gmail.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Content-Type: multipart/alternative; boundary=0050450156274f23b2049093b689

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First, let me make it perfectly clear that I'm not going for the Ed Anderson
"Deadstick" plaque.  Ed has earned it and as far as I'm concerned he can
just as well keep it.

A little background:  I'm running a N/A p-ported 20B powered Lancair ES.
I recently changed back to the old style CAS from the Renesis style CAS due
to inability to get the engine to run smoothly.  This turns out to have been
a good decision because the engine is running much better with the old style
CAS.  With the switch completed, I was ready for some ground running and
some fast taxi runs.  This was accomplished on Friday, 9/17.  It ran very
good, 100% improvement over the other (Renesis) CAS, reaching 6800 rpm
during the fast taxi.  After doing a fast taxi, it felt good and everything
was in the green, so I decided to take a lap around the pattern.
It accelerated and climbed like you would expect from a p-port 3-rotor.  As
I was turning downwind, I thought I saw a faint bit of smoke in the cabin.
I tried to detect if it was electrical in nature or oil.  I thought it
smelled more like oil.  I throttled back and watched the EM-2 for a sign of
what could be wrong.  About 3/4 ways down the downwind leg the oil pressure
had dropped and was reading 53 psi.  (The oil pressure normally runs around
80psi.)  I throttled back, announced my intentions, and headed for the
numbers.  I was the only a/c in the pattern at the time.  I had to slip it a
bit, but got on the ground without delay and taxied off the runway and
parked.  The oil pressure had dropped to 14 psi bythe time I got it
shut down.  The whole episode maybe lasted 2 minutes.

Upon climbing out I could see that there was oil blown out of the side cowl
seams all down both sides of the fuse (I'm fortunate it didn't coat the
windscreen).  Oil was dripping out the nose gear fairing and was forming a
puddle on the asphalt.  I tried to imagine what could possibly have
failed... oil line, oil cooler, oil filter, etc.  I towed it back to the
hangar and pulled the upper cowl.  A quick look and it was evident that the
rear psru seal was the cause.  It had come out of position and had rubbed on
the damper hub until it abraded through the rubber.  This allowed oil to
flow out around the input shaft at the rear of the gearbox and be sprayed
all over the inner cowl.  Yes, I'm very lucky there was no fire!

I would like to point out that while I'm running an RD-2C gearbox, I'm
using a custom adapter plate which relocates the starter to the plugs side
of the engine.  The seal is strictly a press fit into a counter-bore in the
1/2" aluminum plate with no mechanical locking device.

I have since removed the gearbox and plan to install a new seal with
two flathead screws which will be positioned so as to mechanically
retain the seal in the counterbore, preventing a recurrence.

I post this only to make others aware of a potential failure mode that they
may otherwise not recognized as such.

Mark

--0050450156274f23b2049093b689
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<div>First, let me=A0make it perfectly clear that I&#39;m not going for the=
 Ed Anderson &quot;Deadstick&quot; plaque.=A0 Ed has earned it and as far a=
s I&#39;m concerned=A0he can just as well keep it.</div>
<div>=A0</div>
<div>A=A0little background:=A0 I&#39;m running a N/A=A0p-ported 20B powered=
 Lancair ES.=A0 I=A0recently changed back to the old style CAS from the=A0R=
enesis style CAS due to=A0inability to get the=A0engine to=A0run smoothly.=
=A0 This turns out to have been a good decision because=A0the engine is run=
ning much better with the old style CAS.=A0 With the switch completed, I wa=
s ready for some ground running and some fast taxi runs.=A0 This was accomp=
lished on Friday, 9/17.=A0 It ran very good, 100% improvement over the othe=
r (Renesis) CAS, reaching 6800 rpm during the fast taxi.=A0=A0After=A0doing=
=A0a fast taxi, it felt good and everything was in the green, so I decided =
to take a lap around the pattern.=A0 It=A0accelerated and climbed=A0like yo=
u would expect from a p-port 3-rotor.=A0 As I was turning downwind, I thoug=
ht I saw=A0a faint bit of smoke in the cabin.=A0 I=A0tried to detect if it =
was electrical in nature or oil.=A0 I thought it smelled more like oil.=A0 =
I throttled back and watched the EM-2 for=A0a sign of what could be wrong.=
=A0 About 3/4 ways=A0down the downwind leg=A0the oil pressure had dropped a=
nd was reading 53 psi.=A0 (The oil pressure=A0normally runs around 80psi.)=
=A0 I throttled back, announced my intentions,=A0and headed for the numbers=
.=A0=A0I was the only a/c in the pattern at the time.=A0 I=A0had to slip it=
 a bit, but got on the ground without delay and=A0taxied off the runway and=
 parked.=A0=A0The oil pressure had dropped to 14 psi=A0bythe time=A0I got i=
t shut=A0down.=A0 The whole episode maybe=A0lasted 2 minutes.=A0=A0</div>

<div>=A0</div>
<div>Upon=A0climbing out I could see that there was oil blown out of the si=
de cowl seams all down both sides of the fuse (I&#39;m fortunate it didn=
9;t coat the windscreen).=A0 Oil was dripping out the=A0nose gear fairing a=
nd=A0was forming a puddle on the asphalt.=A0 I tried to imagine what could =
possibly have failed... oil line, oil cooler, oil filter, etc.=A0 I towed i=
t back to the hangar and pulled the upper cowl.=A0=A0A quick look and=A0it =
was evident that the rear psru seal was the cause.=A0 It had=A0come out of=
=A0position and=A0had rubbed on the damper hub until it=A0abraded through t=
he rubber.=A0 This allowed oil to flow out around the input shaft at the re=
ar of the gearbox and be sprayed all over the inner cowl.=A0 Yes, I&#39;m v=
ery lucky there was no fire!=A0</div>

<div>=A0</div>
<div>I would like to point out that while I&#39;m running an RD-2C gearbox,=
=A0I&#39;m using=A0a custom adapter plate=A0which relocates the starter to =
the plugs side of the engine.=A0 The seal is strictly a press fit into a co=
unter-bore in the 1/2&quot; aluminum plate=A0with no mechanical locking dev=
ice.=A0=A0</div>

<div>=A0</div>
<div>I have since removed the gearbox and=A0plan to install a new seal with=
 two=A0flathead screws which will=A0be positioned so as to=A0mechanically r=
etain=A0the seal in the counterbore, preventing=A0a recurrence.=A0=A0</div>
<div>=A0</div>
<div>I post this=A0only to=A0make=A0others aware=A0of a potential failure m=
ode that=A0they may=A0otherwise not=A0recognized as such.</div>
<div>=A0</div>
<div>Mark =A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 </div>

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