> >>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
This gives me a thought for a test I will do as with a seaplane I
can do things that most will not do as I have runways all over there
to hit.
I can disconnect one trailing plug and put a switch so that I can
kill one leading of my leading coils to find out how it will fly
with one dead rotor.
Another highly possible thing that can happen if apex seals fail in
one rotor is that they can get spit into the intake and get swallowed
by the other rotor and take it out also, this has happened to me many
times with my off road race cars with piston engines.
Ken Welter
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