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  #11  
Old 09-03-2019, 04:06 AM
FredMagare FredMagare is offline
 
Join Date: Mar 2006
Location: Kyle, TX
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Quote:
Originally Posted by Pilotjim77 View Post
Should the oil breather be depositing oil after the engine stops running? This is the only way I can imagine it is got there.
The breather line will have a fine mist of oil in the line and on the walls of the tube. I think it possible that this oil might continue to slowly drip out on to your exhaust after shut down. An air/oil separator would reduce the amount of oil that drips down. (Ensure you eliminate all other possible sources of the smoke first.)
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  #12  
Old 09-03-2019, 06:04 AM
YvesCH YvesCH is offline
 
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Location: Basel, Switzerland
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Quote:
Originally Posted by Pilotjim77 View Post
With these responses, another thought just occurred to me. The right wing flap got jammed under the wing skin when I was raising the flaps prior to taxi. Could the flap motor be causing this problem?
So your right flap was jammed? Did you find out why? I know ist off-topic but still interesting to know what happened
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  #13  
Old 09-03-2019, 06:13 PM
Pilotjim77 Pilotjim77 is offline
 
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Location: CHESHIRE, MA
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Originally Posted by YvesCH View Post
So your right flap was jammed? Did you find out why? I know ist off-topic but still interesting to know what happened
Probably bumped the flap with my leg when it was fully extended during preflight inspection. I put some marks on the flaps now so as not to fully extend them on the ground.

Thanks for all the other responses. I still have not found the source of smoke. I'm getting a very faint odor of smoke after start up, but no visible smoke. I checked the flap motor and wiring... no sign of burning or melting. No wiring or connections beneath the panel look burnt or melted. Nothing feels hot. Sure wish I could locate the source.
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  #14  
Old 09-03-2019, 07:30 PM
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Vlad Vlad is offline
 
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Last suggestions for you Jim. If there was no visible smoke in the cockpit but a strong smell it could be exhaust gases. It happens very rare usually if you are idling while holding short and there is a slight tailwind. It comes via fresh air vents. Or descending at prolonged idle from high altitudes.
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  #15  
Old 09-03-2019, 08:54 PM
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Bill Boyd Bill Boyd is offline
 
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Location: Landing field "12VA"
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Default mine does this on rare occasions

My engine drips a bit of oil from here and there - kind of expected at 900+ hours. One time, that oil made its way onto an exhaust pipe, and into the heat muff. You can imagine the effect on start-up, as the cabin heat valve was open

Lots of smoke in the cockpit, but it cleared rapidly as the stain burned off.

Yes, I shut down and decowled to check things out.

Any more, I don't panic if I get a brief smell of burning oil on start-up, so long as it clears quickly. I never open the heat valve until the engine has been running for a few minutes on the ground. I can abide the odor, but not smoke in the cockpit. Part of learning the aircraft, I suppose. Keeping the engine wiped down every time the cowl is off goes a long way to mitigate this thankfully rare occurrence. I suspect your issue is similar.

With winter just around the corner, I will have to re-establish the habit of not opening the cabin heat too early in the start-up sequence.
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  #16  
Old 09-03-2019, 11:11 PM
moosepileit moosepileit is offline
 
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Location: Floyds Knobs, IN
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If your breather is above a tailpipe I found, following Smokey Ray posts, that it did not allow enough flow out the breather.

That might make leaks and up consumption and mess. It is too high a pressure area in the lower cowl. Sounds like it has nothing to do with your smoke, but a breather that clears the lower cowl seems best. Especially when not using an air oil seperator.

I no longer have to wipe 1/2 teaspoon of oil off the belly aft of the breather each flight and no oil on the tailpipe. Cut it so there is a 45 degree slant, more open to the trailing side.

For freezing protection of your nose seal, make sure there is a whistle slot or relief slice near the highpoint of your breather line.
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  #17  
Old 09-04-2019, 07:31 AM
maus92 maus92 is offline
 
Join Date: Nov 2013
Location: Annapolis MD
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Quote:
Originally Posted by FredMagare View Post
The breather line will have a fine mist of oil in the line and on the walls of the tube. I think it possible that this oil might continue to slowly drip out on to your exhaust after shut down. An air/oil separator would reduce the amount of oil that drips down. (Ensure you eliminate all other possible sources of the smoke first.)
Oil will definitely drip out of the breather line after shut down / overnight.
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  #18  
Old 09-10-2019, 07:41 AM
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Snowflake Snowflake is offline
 
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Location: Victoria, BC, Canada
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Another possibility, oil from another gauge dripping on something electrical. Here's a local incident report with exactly that situation:

Quote:
Update TSB #A19P0091: C-GMZA, a Cessna 152 aircraft operated by Canadian Flight Centre, was conducting a local training flight from Vancouver/Boundary Bay (CZBB), BC with a student-pilot and an instructor on board. During the initial climb after the takeoff, smoke was observed coming from under the instrument panel, near the electrical switches. The instructor assumed control of the aircraft, reduced the power, turned off the master switch, and closed the cabin air. The smoke subsided, and the instructor turned the aircraft toward CZBB for a landing. The instructor momentarily selected the master switch to on, communicated a MAYDAY, and re-selected the master switch to off. The aircraft landed and taxied to the ramp. The instructor advised that emergency vehicles were not required. The operator's maintenance found a leak from the oil pressure gauge located above the switch panel, with traces of oil on the landing light switch. The gauge cluster was replaced. There were no signs of electrical fire on the electrical wiring under the dash. dditionally, minor oil spillage was found around the engine oil filler tube. The aircraft was returned to service.
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  #19  
Old 09-10-2019, 10:27 AM
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wjb wjb is offline
 
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Location: Half Moon Bay, CA
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Quote:
Originally Posted by Snowflake View Post
Another possibility, oil from another gauge dripping on something electrical. Here's a local incident report with exactly that situation:
Interesting ... but where did the smoke come from? Oil is not generally very conductive, so it's not likely to be an oil generated short. Something else would have to be hot to generate the smoke .. quite hot! Not sure this incident was properly root caused...
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  #20  
Old 09-10-2019, 11:16 AM
Pilotjim77 Pilotjim77 is offline
 
Join Date: Jun 2018
Location: CHESHIRE, MA
Posts: 226
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Quote:
Originally Posted by Bill Boyd View Post
My engine drips a bit of oil from here and there - kind of expected at 900+ hours. One time, that oil made its way onto an exhaust pipe, and into the heat muff. You can imagine the effect on start-up, as the cabin heat valve was open

Lots of smoke in the cockpit, but it cleared rapidly as the stain burned off.

Yes, I shut down and decowled to check things out.

Any more, I don't panic if I get a brief smell of burning oil on start-up, so long as it clears quickly. I never open the heat valve until the engine has been running for a few minutes on the ground. I can abide the odor, but not smoke in the cockpit. Part of learning the aircraft, I suppose. Keeping the engine wiped down every time the cowl is off goes a long way to mitigate this thankfully rare occurrence. I suspect your issue is similar.

With winter just around the corner, I will have to re-establish the habit of not opening the cabin heat too early in the start-up sequence.
I have checked every electric wire and connection closely and can't find anything. The flap motor wiring looks fine, and the flaps are working with no problems. Turning on all electrical components before startup does not produce any smoke or smell.

I am still getting the smell of smoke shortly after startup with the canopy slightly open, and I'm thinking it's got to be oil from the exhaust. It lasts less than 30 seconds then goes away.
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