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Leading Edge Exhaust -- Exhaust Odor in Cabin on Final

Darrel Starr

Darrel Starr

Registered User
Plymouth, MN
I like the Leading Edge exhaust system on N18SY except for one thing. When I am coming down final, I often get an exhaust smell in the cabin. This seems to happen only when the plane is slowed up and the wing is at a relatively high angle of attack with no crosswind. Exhaust then seems to swirl around and come in the gaps surrounding the door, probably the lower door. Does anyone else with this exhaust system have a similar issue? Has anyone tried a longer exit pipe? I was thinking of having one made up that is about 2 inches longer with a straight cut on the outlet, not the extreme angled cut on the outlet opening that comes from the factory. I tried emailing Leading Edge on this issue but got no reply. The Sutton exhaust seems to have a much longer pipe.
Thanks, Darrel
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I've been running the LEE's since 2007. I have not had what you are experiencing happen to me. But I do have the extended overboard pipe. Got it from the factory with the normal 45 cut. My exhaust works great!! But it did dirty up my AOSS can. Pic's in the galley if you care.
 
I get it with the Sutton as well, hi angle of attack, comes in the door I guess. I'm continueing to seal the door for cold and warm air. Only on final.
 
I just took a look at your pictures -- didn't know there was a longer pipe available. Did you have to special order it? I can't get a response to my emails from LEEs so I will call them when I return home. My system is one of the first ones so they might have changed to a longer pipe later on.
Thanks JK, Darrel
 
No special order, but while talking with Dane he asked if I had a pod and suggested the extended pipe. Said If I didn't like it I could cut it down, so I went long.
 
Fortysix12,
I am concerned if you are getting exhaust fumes in the cabin. Is your pipe still full length or did you cut it off? If it is still full length and you are smelling exhaust, please look it over very closely to make sure everything is okay. I also have a removeable tailpipe with a 45 degree bend which will allow you to direct the flow if it would help. Just let me know..

Brian Sutton
Professional Pilots Inc.
 
I remember a discusion on the 170B web site about which way the 45% was pointed (face front or face aft). Anyway can you easely turn your tall pipe? Ie straight pipe held on with clamp. If so why not try turning to a different angle ( front,left or right). If nothing else it will give you a reason to go fly.
 
With my stock exhaust(pa-18 style) on the 12 I would always get exhaust stink in the cabin when flying slow or on final. When I switched to the sutton there is no more exhaust smell or CO indicated on my CO detectors. I even had a foot long extension on the other system to try to get it away from the fuselage. A few things you can check to seal up some leaks are the metal belly could be scooping it up at higher angles of attack, if you have one, and other places to check are around the doors and gear legs. The sutton doesn't have an angled cut like most have that could have something to do with the way the exhaust exits the pipe.
 
Thanks folks -- I will check around the gear legs for openings and look to see if I can turn the scarfed end some. But it looks like a longer pipe with a straight cut might be the answer.
 
I think the plane is reasonably tight concerning openings back and underneath but I will look around again.
 
I'm not saying that this is your situation, however it may be worth considering. Fuselages by the nature of their shape generate a lower air pressure within and tend to draw air in from the tail thus the exhaust incursion. To reduce this tendency of exhaust air getting to the cabin some have a vapor barrier just at the aft end of the passenger compartment. Some also have forward facing air scoops placed at the tail up above the exhaust trail to increase the internal pressure to oppose the exhaust air incursion.

If you have fresh air inlets, open them all and test for the exhaust smell on final again. There may not be a problem with your exhaust system at all. Perhaps you have done too good of a job closing off annoying cold air leaks?
 
You may have a point, this issue has reared up on the cooler days , it seems, when I don't have much if any fresh air coming in -- still, I would like to fix the issure during all ambient conditions.
 
This is a timely thread.
I planned on bringing this same issue up after a flight last night and one last week. I get the same exhaust smell and unless I open the window, about half way, it sets off my carbon monoxide detector. The exhaust system is an original and it looks a little suspect. (This is a New Plane to me---- just joined the supercub ranks)
I was going to ask about aftermarket high performance exhaust systems. Good ones, best results. However, I do need the exhaust pipe to exist the same location as the original.
I have seen some pictures of the exhaust exiting further forward and I assume those are aftermarket systems.
Any suggestions on the aftermarket exhaust or point me to a former thread on the subject would be appreciated. -----tom
 
Barbwire the Sutton exhaust is as simple as it gets. It is simple to install and simple to maintain. I am very happy with mine on a PA-12. No more exhaust stink period. Do a search for the Sutton on here. I must have started a trend where I live because I know of at least two cub owners at the airport that put on new Sutton exhaust systems after I installed mine. You do have to cut a new hole in the bottom cowl which is the hardest part of the whole installation but everything else is straight forward.
 
Any airplane with a stock system that is getting exhaust in the cabin is certainly suspect for a cracked muffler.

A friends borrowed -18 nearly killed me with the smell. I was so loopy. Had trouble landing on the mountain I wanted, and had to go to an easier snow-field to get fresh air. He had a new belly pod and thought the pod was causing airflow problems, went with a long pipe and the next weekend I nearly died in the back seat, had to stick my nose out the window....no fun.

The airplane had come out of rebuild and his muffler "...was good when I annualled it..". Finally he checked it.....cracked muffler!
 
Darrel,

This is off topic a little, but that is the cleanest, nicest looking belly on you plane. Looks like you could eat off it!

Andre
 
Thanks for the help Trapperty and Dave. I have ordered the Atl.D. Hot Rod as it will fit the cowl. I cannot bring myself to cut a hole in a three week old cowl from Dakota Cub with a beautiful paint job. Talked to Brian Sutton and like his product butttt it gets back to the cowl hole!!!!
 
Andre, thanks for the comment -- I'm retired so there is no problem lavishing time on the plane keeping it clean.
If you blow up the first of the three pictures above by clicking repeatedly on it, you will see one of the smarter things we did during the restoration. Bob Eckstein had the idea that I should make overlapping aluminum belly covers beyond the boot cowl to give easy access to the area back to and slightly beyond the rear brake pedals and master cylinders. These panels meet in the middle under the belly. Bob welded on extra 3/8 inch channels to support them with Rivnuts. We take these off at each annual. They are proving to be very handy such as the time we had a brake line leak shortly after the rebuild.
Darrel
 
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