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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