From:
Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Ed Anderson
Sent: Saturday, December 23, 2006
8:31 PM
To: Rotary motors
in aircraft
Subject:
[FlyRotary] Re: Dead Rotor at 3000ft
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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