Joe,
Sorry to hear about your problem but glad to hear you brought her back
safely. Does certainly appear you have a bad apex seal. You might
want to check your ignition timing. I once mistakenly (of course - who would
to it intentionally {:>)) sat my static timing to 45 deg rather than
35. I noticed while flying that If I opened up the throttle wide open the
note of the exhaust changed to a staccato popping. Well did not
fortunately lose an apex seal but I found the center electrode ceramic cone was
missing for two of the 4 plugs and cracked on the other two. Just lucky
they didn't take out the apex seal. So you might check that timing just
to be certain.
-----
Original Message -----
Sent: Saturday, December 23, 2006 11:15
PM
Subject: [FlyRotary] Dead Rotor at 3000ft
The
weather today in the Seattle area was marginal for flying – but a nice hole
opened around my home airport (KAWO) and I was there tinkering with the plane
anyway (re-torqueing the prop)– so up I went. I did 4 touch and goes just for a
wee bit of practice and then departed the pattern toward a bigger hole that
would be legal to climb through VFR. I flew about 30 miles northwest of the
airport out to the edge of the Puget Sound and
enjoyed just being in the air. Power setting was about 4400RPM and I was loping
along at a lazy 135kts. I turned around and headed back for Arlington and decided to
ramp up the power to ramming speed – errr I mean cruising speed. In a few
minutes I was cruising along at 170kts at about 5500RPM. Then all of a sudden
BAM – the engine stumbled and RPM's dropped to 2300RPM. I immediately
throttled back and switched tanks while turning toward the airport. Altitude
was 3200FT (about 3000AGL) and I was maybe 7 miles from the airport. The engine
was running real rough and wouldn't give me more than 2300RPM. Even with that
little bit of power I ended up entering the 45 to the pattern at about 800
above pattern altitude. It was pretty slow at the airport so I easily made a
normal landing and was able to taxi back to the hanger under power.
At
the hangar I double checked everything I could from the cockpit – fuel pressure
good at 36PSI, oil pressure good at 55PSI at 2300 RPM, MicroTech ECM showed
"OK" for the size major areas it monitors. So, I shut it down and
pulled the cowl. I pulled the prop through a number of times and it seemed that
there was a couple places where I should have been hearing a "pop" in
the exhaust but didn't. I also notice that there is a nice ding in the prop
that is about an inch long – that wasn't there when I left (remember I'm a
pusher).
I
got the engine compression gage and proceeded to take the spark plug out of the
front rotor – top – BR9EQ-14. Hmmm – I don't remember there being a casing
around the electrode – and why is that casing sliding? Apparently the
casing around the electrode broke somewhere inside the sparkplug and into two
halves long ways down the electrode. Each half slides freely up and down the
electrode and even sticks out a little from the end.
I
put the compression gage on and it looks like I get 30-30-70 when I turn the
engine over. I tried this several times and there is definitely a couple of
places where it only goes to 30. So I double check the location of that ding in
the prop – hmmm it's exactly even with the bottom of the exhaust – right about
where an apex seal would come out.
I
put two new BR9EQ-14's in both rotors and did a quick run – 2300RPM rough is
the best I could get.
Some
time this week I'll go up and yank the exhaust so I can see the apex seals – my
guess is I'm missing at least one. Bummer.
Joe
Hull (getting tired of little surprises in the air).
Redmond/Seattle
WA, Cozy-Mazda Rotary 71hrs
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