REFLECTOR: Another rear cowl anomaly!

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Very perplexing!  Sounds like the soot pattern could only occur with the prop NOT turning too. So the flame occurred during start or shut down as you suggest.  Flooding fits. I sure know that look from the right seated well after a precautionary landing on my first cross-country in the Velo.  Very hard to reassure yourself and the passenger if one can not find the culprit.  Doesn't sound like a test under like circumstances is wise either without an observer with an extinguisher. 
Good luck.

Sent from Rene's iPad.


On Nov 27, 2011, at 8:08 PM, Scott Derrick <scott at tnstaafl.net> wrote:

> 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
> 
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