Hi Mark,

 Glad you got back down OK.

 

Just one comment.  There should not be 90 - 100 PSI trying to push the seal out.  The oil pressure drops through the passage in the input shaft and is dissapated by the oil flowing out through the thrust bearing stack.  There should be very little pressure on the seal.

 

Tracy (in Colorado)

On Sun, Sep 19, 2010 at 3:40 AM, Mark Steitle <msteitle@gmail.com> wrote:

Kelly, 

My custom adapter plate was built on a Bridgeport mill.  The hole spacing (and sizes) were obtained from a drawing for the actual RD-2C plate.  Could it be a thou or two oversize?  I guess that's possible, but I don't think so.  The machinist that did the work is very meticulous.  However, before reassembly, I'll definitely check it to be sure.  The bottom line is that there is 90-100 psi trying to push it out of place.  So, I feel that a mechanical fastener is the only real way to guarantee that it stays put 100% of the time.  

Mark

On Sun, Sep 19, 2010 at 12:28 AM, Kelly Troyer <keltro@att.net> wrote:

Mark,

   Do you think your custom adapter plate counter-bore may be slightly large in ID

which could have allowed the seal to work loose ??..............Just a thought as my

adapter plate is custom (not from Tracy) to adapt my RD1C to a Mazda automatic

transmission bell housing much like Bulent's "Cosy" Cosmo 13B installation.........

   I will compare the counter-bore of the plate from Tracy to my custom plate and

also add a mechanical retainer such as you describe...............Seems like cheap

insurance against a failure that could kill your engine in 2 minutes plus potentially

cause an inflight fire.........Good Thinking and flying Mark !!..............

 

Photo attached

 

Kelly Troyer
"Dyke Delta"_Turbo/13B ROTARY Engine(Eventually)

"RWS"_RD1C/EC2/EM2
"Mistral"_Back-plate/Oil Manifold

---

From: Mark Steitle <msteitle@gmail.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Sat, September 18, 2010 9:40:00 PM

Subject: [FlyRotary] Watch that psru oil seal

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           

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