Jeff Vaughan

Jeff Vaughan

Well Known Member
Can't you smell that smell
I am stumped. On the last half a dozen landings or so just as I pull off of on to the taxi way I smell an odor of burnt rubber. Like a car tire burn out smell. It lasts a few minutes and then it is gone. My passengers have smelled it too. I have taxied back to the hangar,jumped out , sniffed around thre cowl , in the oil door, but no rubber smell. I have taken the cowl off and can not find anything that looks as if it is causing the smell. I have a very normal engine set up. TMX-0360, with Lightspeed and mag. Baffles are clear of all moving parts. The smell started around the 40 hour mark. The only rubber I have under the cowl is some auto fuel line that protects the throttle cable and miture cable plus the Lightspeed crank sensor wire. No obvious burns or melting. Strange that it goes away as quickly as it comes.

Anyone else experience this?
 
Check your tire pressure & gear fairing openings. Extra weight may be burning your sidewalls a little on smackdown.
 
Smell

Have smelled the wheel pants at landing but no odor. However you may be on to something here. I did install the wheel pants not so long ago. Did take them off today and inspected them,No obvious indication of rubbing. I think I will enlarge the openings alittle. Can't hurt. Tire pressures: Nose 30 , Main 35
 
Brake smell?

Do aircraft brakes smell like car and truck brakes? If so I do not believe I am confusing the two. If they do smell like rubber why isnt everyone experiencing the rubber smell?
 
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I say track it down. In my experience every new smell or sound is coming from somewhere and it could be important. At least mine have been but I have a very non standard engine setup and have had to chase down my share of bugs. They can be elusive but rewarding to find and you know you have solved a potential problem.

Randy C
 
I get a rubber smell from the tires
spinning up when landing. I touch
down at a slower speed now and the
smell doesn't seem as bad.
The tire smoke must come up the
gear leg fairings like a chimney.
You could seal up the leg fairing
if you want. Taking off the wheel
pant should also eliminate the smell
if you want to verify the source.

Tom
 
Gear leg openings

tomwebster said:
I get a rubber smell from the tires
spinning up when landing. I touch
down at a slower speed now and the
smell doesn't seem as bad.
The tire smoke must come up the
gear leg fairings like a chimney.
You could seal up the leg fairing
if you want. Taking off the wheel
pant should also eliminate the smell
if you want to verify the source.

Tom
Click to expand...

Is it a tricycle gear? If so then you have cut outs for the gear legs. Did you seal those cut outs around the gear legs with proseal? I haven't ever smelled rubber. My gear leg opening are sealed. Just a thought!
 
This might be a dumb question, but are you on the brakes at all when you touch down? I have run into the same problem on certified aircraft and what I tracked it down to was the owner was on his brakes at touchdown. When the wheels would touch they would actually spin on the rim of the tire. This went on for a while to the point where valve stem actually pulled out of the wheel as the tube rotated with the wheel. This might be the issue.

If you only smell it on touchdown then I would go with it is something with the wheels/tires. If you said that you had just installed the wheelpants not that long ago, take them back off and go fly, does the smell come back.

I have run into a lot of aircraft that have a problem, and then after 3 or 4 hours of troubleshooting the pilot/owner says the typical "o yeah I was fiddling with this or that the other day". If you have recently changed something on your aircraft and have an issue that doesn't seem like it would relate, go to the thing you changed first. It may save you a lot of curse words and head scratching..
 
compensating ports closed

Sounds like the master cylinders aren't completely extending all the way at rest. If they don't extend all the way at rest, then the compensating port in each master cylinder will remain closed and trap residual pressure in the calipers. Then when you touch down on landing, the tires skid a bit before rotating. Van's used to sell slightly stiffer return springs to help keep that from happening. I had to do that to my -6. The fact that this has only been happening for the last few weeks leads me to believe the return springs are getting weak.

All master cylinders, even automotive ones, have compensating ports. They're necessary to bleed off pressure from heat/cold expansion/contraction and hose swelling. And the port is only open when the master cylinder is completely extended.

Heinrich Gerhardt
RV-6
 
My Thoughts

I would check the rubbing of the wheel on the wheel pant (which you already have), and check your alternator belt to make sure it isn't rubbing any baffle material.
If it was rubbing the wheel pant you would see some black rubbing marks on the wheel pant and see some wear on the tires. I would think it would be obvious if it is enough to smell it.

Also, what did you use to seal up your baffles around the engine? Silicon? RTV?
Could you be burning that?
 
tomwebster said:
I get a rubber smell from the tires spinning up when landing. I touch down at a slower speed now and the smell doesn't seem as bad. The tire smoke must come up the gear leg fairings like a chimney. You could seal up the leg fairing if you want. Taking off the wheel pant should also eliminate the smell if you want to verify the source.
Tom
Click to expand...
bhester said:
Is it a tricycle gear? If so then you have cut outs for the gear legs. Did you seal those cut outs around the gear legs with proseal? I haven't ever smelled rubber. My gear leg opening are sealed. Just a thought!
Click to expand...

I have a 6A and get the smell. It is the tires. It happens so soon after touchdown that I suspect that it is the tire contacting the runway and the puff of tire lost to the spin up from 0 to 60 in a billionth of a second that causes it. I fly with only socks on my feet so I can feel that I am NOT in any way touching the brakes. I almost always get the smell and I have long ago surmised that it is the "chimney effect" and do not worry about it. The tire smell is NEVER present on the taxi to the runway. It will linger for several seconds after landing but is gone by the time I taxi to the hanger. My tire wear is normal and the tires are not contacting the wheel pant on their sidewall.

I use the smell as an indicator that I have actually touched down since my landings are so undetectable to the pilot or passenger by any other means! :D
 
hgerhardt said:
Sounds like the master cylinders aren't completely extending all the way at rest. If they don't extend all the way at rest, then the compensating port in each master cylinder will remain closed and trap residual pressure in the calipers. Then when you touch down on landing, the tires skid a bit before rotating. Van's used to sell slightly stiffer return springs to help keep that from happening. I had to do that to my -6. The fact that this has only been happening for the last few weeks leads me to believe the return springs are getting weak.

All master cylinders, even automotive ones, have compensating ports. They're necessary to bleed off pressure from heat/cold expansion/contraction and hose swelling. And the port is only open when the master cylinder is completely extended.

Heinrich Gerhardt
RV-6
Click to expand...

Heinrich, I like this as a possibility and will check to see if I am a victim of this possibility. The smell is for sure tires IMO and in my case because of the lack of smell at any other time than landing. Thanks for the thought.:)
 
I use the smell as an indicator that I have actually touched down since my landings are so undetectable to the pilot or passenger by any other means! :D[/QUOTE]

I have a light on the instrument panel that says
'Have Landed" as soon as the plane has touched down, or else they wouldn't know.
 
take a look....

at the top intersection fairings on your gear legs. You will most likely see brake dust starting to migrate up the gear leg fairing on to the belly skin. This is common, and normal for our planes. That puff of tire smoke is sucking right in the wheel pant, up the gear leg, under the spar box, out of the stick hole, and right up your nose. The fix is to seal the gear leg socket opening with some pro seal next time you have the fairings off.

Been there!!
Chris
 
Thanks for all the great info. I will first seal the openning around the gear leg and report back with my findings. Have to wait a few days as we are in the midst of a snow storm.
 
Can't smell

Due to severe seasonal allergies I have a seriously deteriorated sense of smell but I've had passengers comment on a "burning rubber smell". It only happens upon landing and I just attributed it to using the brakes for differential steering; heat from the braking action. By the time I'm at the hangar, the smell is gone. Don't know for sure. I've checked the wheel fairings and while I sometimes can feel a bit of heat on the fairing near the calipers, I've checked the fairings for any sign of damage or deterioration on the 'glass, and all looks fine. As a remedy, I use the brakes for steering only when going very slowly. My pad thickness seems to be holding up well so, I don't really know..... YMMV.
 
I've had this smell too... Found out my tire was rubbing top of the wheel pant... remounted to give more (head room) to speak, and that went away..However, I still smell it once in awhile on landings... And can concur that it's probably the tire scrubbing on touchdown..the smell comes right up the gear leg fairing.. Also, if I overuse my brakes too much, I smell them too... Sheldon
 
Brakes on touchdown!

MNAv8or said:
I have run into the same problem on certified aircraft and what I tracked it down to was the owner was on his brakes at touchdown. When the wheels would touch they would actually spin on the rim of the tire. This went on for a while to the point where valve stem actually pulled out of the wheel as the tube rotated with the wheel.
Click to expand...

That's amazing!!

Barry
Tucson
 
Cabin air inlet??

I wonder too if your location for your cabin air intake is accentuating the smell. Some folks put this under the wing close to the gear, while others have it on the fuselage.
 
Try Grass

You can eliminate tire rubber, as the cause, by making a few grass landings somwhere.
Just a thought.

Tom
 
My cabin air is on the fuse. Since I have an A model the gear leg comes right in the fuse below my knees, a pretty straight path up the leg into the fuse and to my nose. As far as grass landings go I will have to wait for the snow to melt!!
 
The smell is gone!!

This site rocks!!

I sealed up the opening where the main gear legs go through the fuse (7A) with RTV and the rubber smell is gone. It most definatly was comming from the tires and flowing up the gear leg fairing. Thanks for the assistance in solving this mystery!!
 
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Cool!

I am glad you found it.:cool:

I live in a really dry area, when the air does become humid everything smells different and much stronger.
 
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