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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