REFLECTOR: Another rear cowl anomaly!

[Scott Derrick]

Experienced yet another rear cowl anomaly!  And this one with prime 
passenger #1` aboard!  Not good.

Landed at North Las Vegas, this afternoon on the way form Carson City, 
NV to Grants, NM.  Jan went into the terminal to visit the head while I 
started the refueling operation. Got to hooking the ground wire to the 
engine and noticed a dark area around the left hand exhaust pipe. I bent 
down and WOW, black curly soot trails all around the exhaust pipe and up 
onto the wing!

WTF!

I wiped with a rag I was holding and it came right off. No damage to the 
paint. In fact is was just warm, not hot. Still what could have done 
that?  When Jan got back form the terminal I said  I needed to remove 
the upper cowl and inspect the engine. Instant frown! Why? Is something 
broke, is it still safe?

Anyways after removing the upper cowl and looking at the other side of 
the lower cowl where al the soot was there was no evidence of anything 
out of the norm?  No leaking injectors, no oil anywhere near that area?  
Started it up, ran to full power, shut down, looked again, everything in 
place.  I reinstalled everything thinking, I would rather find something 
than not.

Took off watching the gauges like a hawk, everything normal. In fact the 
the plane is performing better than it ever has.

Flew the 2 hour  trip to KGNT, landed, lower cowl is as clean as it 
usually is.

I have been thinking, dangerous, that this was the coldest start yet on 
this engine. I've always preheated here at GNT, but at CXP it sat for 5 
days, and the oil temp showed 30 degrees when I started it. It ran 
really rough after starting to. I'm thinking that when I primed it, 
because it didn't start right away, a good chunk of fuel went unburnt 
through the cylinders into the exhaust, was dripping out when the engine 
finally started and caught fire?

Maybe. Possible? The soot was in pattern's that could only be made while 
stationary.

Ideas?

Other than that a great trip averaging, 180 knots true at 12.5 GPH.

Scott

-- 
It is a miracle that curiosity survives formal education.
Albert Einstein