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