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Smoking Hinge

rvanstory

Well Known Member
I have one side of my cowl hinge that has a trail of "smoke" after every flight. It only happens on the one side. Plane has 70 hours on it. It this a problem I will have to contend with at some point? Or is it simply a tighter hinge that is "wearing-in" and the smoking will stop at some point? Any advice from someone that has experienced the same would be appreciated.
 

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That is from a hinge which is seeing some kind of relative movement during flight. The dark streaks are wear. My opinion is that it won't get better, but that's only an opinion.

My RV-6 has developed this trait over the years as the hinges have worn and allow more relative movement between the hinge halves.
 
Randy,
What you maybe seeing is some run back lubricant from an over oiled hinge. If the hinges were installed per plans then I doubt that they would be "smoking" after 70 hrs. I would remove the cowlings, clean and inspect hinges and lightly lube with a dry lubricant. You might also check to see if you are using the proper diameter pins. The hinge pins at 70 hrs. can still be somewhat difficult to install/remove.
 
ACF 50

Try cleaning the hinge pins well and then coating them with ACF 50 prior to insertion. It will provide lubrication for any relative movement and stop the oxidation of the aluminum hinge which is the black residue you see. I treat mine every time they are out and have been pleased with the results.
 
What did you lubricate the hinges with? LP1/2 or similar?

I took/take a chunk of Boelube and just run it over the pins prior to insertion.
 
It's unlikely an issue of which brand of lubricant you use - wiping the pin down with bearing grease is just as effective. The point is to have only a surface film, not residual lubricant that will in-fact liberate from the hinge at some point.

But you state that the smoke is only noted on one side; assuming you applied and used the same lubricant and installed both sides of the cowl the same way, it's unlikely related to that, but it's more likely have some relative motion occurring in the hinge that ends up resonating at a high enough frequency to cause the "smoke", in much the same way a loose rivet does.

The key point here isn't to better lubricate the hinge and pin, but to stop the movement.

Also, are you certain it's not coming from some other source that's working it's way to the edge of the cowl and out? Have you wiped the smoke off and smelled it? Is there a hint of lubricant? It literally only takes a drop of oil to make the "smoke" you see.
 
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I get this on the same side of my -8. I think it may be the occasional drop from the brake reservoir after going upside down.
 
Door Ease is the ticket

I use "Door Ease" for all my hinges..never any streaking. Its basically a big stick of Parafin Wax (In a big chapstick like tube)made for lubricating household door hinges to prevent the mess of oils. I am using a stick my dad bought 50 years ago..works like a charm and zero mess. Just pull the hinge pin across it and install.
 
Boelube

We all use Boelube during construction and I am sure you will have some spare. Clean the hinges and the pins properly and then use Boelube. I usually scrape it out of the container into my palm and rub it onto the pin.

But then also remember that most of the time when you have flown through rain you will also see the black streaks.
 
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