Chuck wrote:
Well I did not make it to Arlington. I was over the Grand Canyon at
12000 ft when the engine suddenly started shaking and RPM dropped to
3900. Turn on the aux fuel pump, tried backup engine controller,
tried disabling trailing then leading ignition, everything looked
normal but RPM. GPS reported nearest airport was Marble Canyon 21
miles away. Set up best glide, headed for Marble Canyon, looked at
EGT and rotor #1 (rear rotor in RV6, front rotor in car) was showing
<400F. 12 minutes later, Marble Canyon was 1 1/2 miles out but could
not reach it so I set up approach on Highway 89A. It was looking
good until a truck pulling a travel trailer appeared from around a
curve, heading right for my intended touchdown spot. He made no
attemp to pull over, so I had to stay above him. After he passed, I
tried to set it down but did not have enough speed to flare so it
dropped in pretty hard. Got it slowed down and off the road, luckily
there was a nice wide spot waiting for me. I got out and surveyed
the situation, the port wing had struck a highway marker post just
inboard of the wingtip and ripped a 2 foot gash in the lower wing
surface. The main and tail spring gear were all slightly bent from
the impact. Later after the engine and I had cooled off, I pulled
the plugs one rotor at a time, and sure enough there is no
compression on rotor #1. My friend flew up and picked me up, we flew
home, loaded up tools and trailer and made the 8 hour drive up
there, removed the wings loaded it up and headed back to Safford.
It has been an interesting couple of days. It will take a bit longer
than that to repair the damage. I will report on the engine when I
get it apart.
Chuck Dunlap
Real sorry to hear that Chuck.
Thank heaven you made it OK. Congratulations on a saved-my-ass-job
well done. Also good job on the design of the motor mount as the
engine would have dropped out on the road if it had been weak.
Were those three piece apex seals?
For the new people. This is the very first failure of the basic
engine that I have heard about in the five year history of the news
letter. Apex seal failure is common on turbo engines that are subject
to detonation. Apex seal failure is rare on normally aspirated
engines like Chuck's but has been experienced in car engines with the
three piece design. They are less tolerant of high wear. The new RX8
motor has gone back to the two piece design.
Paul Lamar
Hey Chuck,
I was looking for you at Arlington, since you were supposed to arrive
there before me. Really glad to hear there were no injuries. Can you
clarify something: did you have partial power at 3900 RPM on the way
down, extending your glide? If not, what were then conditions when the
engine quit running?
That sounds similar to an apex seal failure I had in a 1987 turbo car.
In that case it was the rear rotor. Suddenly the car lost power big
time. I could keep the engine running by keeping my foot on the gas
pedal. Managed to clutch and brake and keep the right foot on the gas
pedal for 30 miles to get me home, through stop lights and everything.
Once home and I turned off the engine, it would not start again, as I
suspected it would not.
--
Perry Mick
Custom Composite Props
mick@bridgingworlds.com
http://www.ductedfan.com
Perry, sorry to miss you @ Arlington. The engine was running enough to
extend the glide a bit. I had about 8000 ft AGL and I went about 21
miles. I believe the glide ratio of the RV's is 10:1, if that is correct
I should have had a 15 mile glide with no power. It takes about 4100 RPM
to maintain altitude in my ride.
I have not yet tried to restart the engine, it kept running until I
pulled off the highway and shut off fuel, that was all I needed.
Chuck
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