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.
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