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Hi! Ed
Really sorry to hear about your engine problem! But on the other
side of the coin it could have happened on the way to S&F in a
location without an airport.. On the bright side if it is the
plastic out of the intake plenum, it could only be melted on the apex
seal ruining compression (specially if both rotors & all six seals
are affected) the damage may negligible!! Keep us posted. By the
way did you get an improvement with the new manifold?
Regards.
Georges Boucher
-------Original
Message-------
Date: 04/09/05
14:10:18
Subject: [FlyRotary]
No Joy on Sun & Fun{:<(
Folks, for those of you who I hoped to meet
at Sun & Fun this year, its not going to happen.
Story follows:
After the sun broke through the early AM
clouds, I launched at 1000 and found myself with a tail wind
(unbelievable). I started a 500 fpm slow climb to stay under Bravo
airspace and reached 7000 MSL about 20 miles or so on top of a overcast
(clear on the other side), when the fun started.
The first indication was a difference in
the engine sound, then I noticed the EGT on the rear rotor
dropping. #&%^@ spark Plug SAG was my initial thought - but, I
had just put in 4 new B9EQV spark plugs the previous day. Then as
things continued to develop (like EGT went to min 1200F) I noticed that
the EGT (which normally only drops 300F) was at effectively zero (or
bottom of meter at 1200F). Well, as Tracy has mentioned pulling
back on the power generally helps, so I did - no joy. Tried
switching off primary and secondary injectors (alternatively of course)
still no improvement. By this time I had begun a 180 deg turn
(into a now headwind).
I tried varying the mixture control -
switched fuel tanks in case I picked up bad fuel in one tank (see I do
learn) - fuel pressure was 43 psi (nominal), oil pressure was 70
psi (nominal), Oil temp was down to 160F, coolant was also down to 160F
( a bit low). Indicating that perhaps less power was being
produced. The aircraft was now vibrating with the characteristic
one-rotor-running vibration. Altitude was down to 6500 MSL,
but I was making no attempt to hold altitude. Finally can see
ground beneath, home base still 50 miles away. Situation is
continuing to deteriorate, I have increased fuel flow to 14 gph just to
maintain 5000 rpm. A fuel flow of below 12 gph and
the engine starts to unwind as if it is going to
stop.
Now I noticed that EGT on rotor number one
is coming down to around 1500F. Clearly not Sparkplug SAG.
Because of the high fuel flow I though perhaps I had a fuel problem even
though pressure was OK. I had also switched fuel tanks, just in
case on tank was bad. Engine is clearly losing power
progressively. I still had 6000 MSL and was thinking about getting
home, but then decided that going into the headwind I would have very
little glide (ground path) and there were no airfield down wind of me
anywhere within 40 miles.
I decided to divert to Lancaster ,SC
airport (cross wind) as it was the closest and had a 6000 ft runway -
plus I could see it off my left wing. On the way, down I thought
about turning off the engine to preserve any remaining engine power in
case I needed it to make the runway. THEN! I remember saying so
many time, that despite damage - so long as a rotary is RUNNING,
it will stay running - but, if you turned it off you would probably
never get it started again. I quickly switched the injectors back
on while the prop was still windmilling and the engine caught and fired
back up. Actually had 3000 ft when I arrived over the
airfield, so would probably have made it with the engine stopped.
Landing was uneventfully and I turned off on the taxi way with the
engine still running. I notice that it took almost full throttle
just to make the aircraft taxing up a the small incline to the
terminal.
Got parked, uncowled and could find no
evidence of anything amiss - but, clearly I was not going any further in
the air this day.
Then I grabbed the prop and pulled it
through - no evidence of compression on any of the six rotor
faces!
It will be a day or two before I can get
the engine off and torn down to determine the cause of the problem but
here are my two candidates in no particular order other than the
sequence in which they occurred to me.
THIS IS PRELIMINARY, so stand by for
corrections after I open the engine up.
Candidate one (my initial thought) -
the new style B9EQV spark plugs electrodes stuck too far down into the
combustion chamber and all six apex seals got clipped. However, if
this were the cause, you would have though that my several full
throttle runup the day before Or early in my max power climb it would
have happened. Why did it wait until 70-80 miles down the road -
took that long for heat expansion to elongate the plug sufficiently to
clip the apex seals? Hard to believe, but I guess it possible.
These are colder plugs so would stay cooler longer But, I would
have expected that if this were the cause, the effective would have been
immediate or very soon after take off..
Candidate two. I installed the
plastic plenum several days ago and have had a number or WOT runs on the
ground, but this was the first flight. Recall, thought, I
have flown with plastic plenums for a number of hours on previous
iterations of intake systems (three intakes to be precise).
There is a 3/8" wall of plastic separating the primary and secondary
runners inside this plenum. This wall divides the two runners from
each other . When the TB is wide open the throttle plate
edge is at that divider and parallel to it. To
improve airflow I had sanded that divider at the throttle body to a
thinner front edge (a 3/8" blunt wall would hurt
airflow). The thought occurs that perhaps this had
disintegrated and been ingested causing the damage (those powerful FAW
pulses). This would account for the problem not happening
immediately and after the climb to 7000 MSL. I examined the engine
and the exterior surface of the plenum and there was no evidence of
cracks, etc. However, it did not occur to me at the time, while
waiting for the wife to drive 50 minutes to get me, to take off the air
flow tube to examine the internal condition of the plenum, will do
that tomorrow.
Candidate three??? Any other thoughts
before I tear it down and end the mystery??
Oh, to complete the picture with local
color, the local airport manager suggested that I remove my radios
- I asked why? Well it turns out they had theft of
such a week before (just GREAT!). So pulled all the electronic
gear, even took my seat cushions home with me. While removing the
radios - guess who drives up - nope not the wife, yep!, the county's
local detective assigned to the theft case and asks me what I am doing -
well, removing radios, of course. But, all ends well and I don't
get hauled to jail on top of everything else {:>)
So again, my disappointment in not getting
to see many of you down there. Fix it up and fly down Tuesday you
say? Well, even if there were no serious damage to housings or
rotor (I should be so lucky), the guy who sell the apex seal I would use
- is down in Florida - at Sun & Fun I do believe
{:>).
I have already talked with Tracy and
told him of my sparkplug theory, but I now have to give equal (if not
more weight) to disintegrating plenum. But, once again, I am amazed at
the damage a rotary engine will take and continue to produce
power. Here both rotors were damaged -not just one - and yet
I could still manage, at its lowest 3000 rpm) - probably enough
power to keep my RV and me airborne in a long glide to home
(but why chance it when things could get worst). Besides the
prospect of having to make a go-a-round if I misjudged the approach to
our narrow 2200 ft runway was not appealing - 6000ft was
better.
Well, like I always say anything that wants
to break on the ground if just fine with me. Any thing that wants
to break in the air - so long as it gets me safely back to an airpatch
(before dying completely) - is also just fine with me.
My story for the day, now where did I put
that bottle of Whiskey?
Best Regards
Ed
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