Joe,
Sorry to
hear about the problem. Good to
hear though, that you can lose a rotor, still make a safe landing, and taxi
back to the hanger. There are many
problems that could have ended in a worse result. At least you are OK, the plane is OK, and you’re at your
home field.
My spark
plugs are BR9EQ-7’s and 9’s. What
engine do you have ?
Steve
Brooks
-----Original
Message-----
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net]On Behalf
Of Joe Hull
Sent: Saturday, December 23, 2006
11:16 PM
To: Rotary motors in aircraft
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