Protecting paint from fuel stains

dfw11411

dfw11411

Pre-takeoff checklist
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dfw11411
Last summer I discovered that one of my fuel drain valves had leaked onto one of the wheel pants directly below the valve. After replacing the valve I worked hard to remove most of the stain. I didn't fly most of January and then discovered that the remaining old valve and the new valve had leaked onto both wheel pants. Both valves were replaced and tested. Cleaning efforts failed and I paid $1,500 to have both wheel pants repainted. Now I'm worried that another leak could cause the same damage. My A&P opined that more wax wouldn't work but a clear seal coat of unknown type might. We both discounted a self-adhesive plastic sheet (like a phone screen protector). Any suggestions?
 
GeorgeC said:
previously:
www.pilotsofamerica.com/community/threads/how-do-i-clean-this-100ll-staining.125696/
www.pilotsofamerica.com/community/threads/100ll-blue-stain-on-wheel-pant.106792/
www.pilotsofamerica.com/community/threads/fuel-stain.9852/
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Thanks for this info. These are removal techniques and we tried most of these without success. My A&P was surprised that 100LL with lots of elbow grease had no effect. The paint shop finally used a car polisher with polishing compound. Removed quite a bit of paint with no effect on the stain. They decided any more polishing would expose the fiberglass shell - the stain soaked in that deep. The stains were larger and darker than the photos in these previous threads. What I found interesting from your cited threads was that the dye fades over time. None of us knew that. The initial stain was left on for about 3 months and we saw no fading. Of course, this aircraft is always hangared and the low wings block direct sunlight.

I was hoping for a preventative or protective measure. If Piper had only moved the drain valves over a few inches!
 
What kind of paint was on the pants, previously? I suppose you could just take 'em right off, Deliverance style. Or run mogas.
 
dfw11411 said:
Last summer I discovered that one of my fuel drain valves had leaked onto one of the wheel pants directly below the valve. After replacing the valve I worked hard to remove most of the stain. I didn't fly most of January and then discovered that the remaining old valve and the new valve had leaked onto both wheel pants. Both valves were replaced and tested. Cleaning efforts failed and I paid $1,500 to have both wheel pants repainted. Now I'm worried that another leak could cause the same damage. My A&P opined that more wax wouldn't work but a clear seal coat of unknown type might. We both discounted a self-adhesive plastic sheet (like a phone screen protector). Any suggestions?
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Try to be with your plane more often to keep an eye on these kinds of things. Put catch buckets under each drain valve? I think that is what I would try to do?

I have always been able to remove 100LL from my paint as I had the right fuel tank leak over a period of time when I cleaned it off for a few months until I replaced the tank. But I was cleaning it off daily within a day of flying it. At the end it right before I replaced the tank it was coating pretty much the whole right side of the fuselage after a 2 hour flight. Plus the gas mileage sucked! lol

BTW my paint is 80% Dupont Imron since it's been repaired 35 years ago, toughest paint ever made. IMO
1980 250 hr C172N tornado total that my late friend bought from the insurance company 1990. He had it repaired and he and 2 other owners flew it/owned it for 1400 hours before me. I started flying it at 1416 hrs. Pretty sure my leaking fuel tank was from a reused fuel tank from this tornado that was not airworthy? I flew it 800 hrs before the tank leaked. I could hear it oil can each time I filled it. Caused a crack on the bottom after may cycles.
4aab4977-796e-463a-a685-07d23132a031.jpg
 
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I have fought this on multiple airplanes. My personal conclusion is that the only way to avoid the deep stains is to catch it early and clean off with a rag and gas just as soon as possible. They do fade somewhat in sunlight. If I have a dripping drain that I can't get to right away I will knot up some paper towels and position the knot where the drip will land. The gas evaporates so fast that unless it's really running out the drips just dry up and the dye stays on the top layer or towels.

From what I have heard about the replacement fuels we may be longing for the days of a little blue stain when the new stuff if rolled out.
 
This is an opinion that needs to be fact checked, but I think cured paint that is slightly soluble in the fuel chemistry causes these issues. I have old DuPont Imron paint and I can remove stains on the paint with carb cleaner without damaging it.
 
1. Paint the wheelpants blue, or...

2. Buy a taildragger. Their wheels aren't under the drains.

But all kidding aside, these things leak because the fuel tanks and drains aren't being maintained. Cessna wants tanks drained every 1000 hours and inspected for internal debris. Junk moving around in the tank eventually gets under the drain valve seal and causes a leak. Those valves themselves don't last forever, either. Their seals are just neoprene and deteriorate in the fuel and with temperature changes. That seal hardens and cracks and now we have a leak. The valve bodies and plungers are often made of plated steel, and the plating wears off and now we get rusting between the plunger and body. If the spring rusts and fails you are really in trouble. That spring holds the valve closed.

In the flight school we changed those valves on every airplane every couple of years. We let some fuel run out of the tank into a clean (grounded!) bucket so we could check for debris. The removed valves we cleaned up and put new seals on them ready for the next change.
 
Brake cleaner works well on imron.
 
The original paint was DuPont Imron Polyurethane. Not sure if the wheel pants had been repainted since new. The new paint is something else. Aviation paint but not Imron.

Both tanks were drained and checked 3 years ago. Of course, contamination can reoccur.

One of the leaky valves was less than 6 months old. Apparently the manufacturer replaced it under warranty.

I'm shaking my head reading all the comments that 100LL, iso alcohol, 409, polishing compound, etc remove stains. We tried them all with no luck. I wanted to try acetone, but was talked out of it. I don't think we tried carb cleaner, IIRC or MEF. I know the A&P and paint shop tried a lot of things.

Not sure how well my TIO-540 would appreciate running on MOGAS. :)

Drip catch buckets! Yes! :) We talked about that early on. I've tried to take off twice with the pilot tube cover attached. I can't imagine the trouble I'd be in with buckets still dangling from the fuel drain valves!
 
Been there done that even with two part catalytic clear coat. Even a replaced o ring or new drain valve is subject to that foreign particle that gets wedged in the seating area and results in slow seepage that is not easily detectable. So as part of my post flight I pull a heavy mil trash bag over each wheel pant. On a tie down maybe something similar that would resist being blown off but outside it seems any small amount of seepage weathers off before accumulating enough to drip.
 
Would 3M clear paint protection film work (the stuff they use on car hoods, etc)?

I use it on my motorcycle tank near the front of the seat so that my winter riding gear doesn’t beat up the paint. It’s great on compound curves, is barely visible, and you can simply peel it off and replace when it gets unsightly. A roll on Amazon is around 3-50.00.
 
dfw11411 said:
Drip catch buckets! Yes! :) We talked about that early on. I've tried to take off twice with the pilot tube cover attached. I can't imagine the trouble I'd be in with buckets still dangling from the fuel drain valves!
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Just tell them you're training for aerial firefighting in case they ever call you for back-up.
 
Instead of a "phone screen protector film," how about a vinyl decal? You would need to test the flow path or review old photos taken before the repaint to determine the area that needs to be covered with vinyl. I would suggest a 100LL Blue colored decal. ;)
 
Use at your own risk, but my original Mooney 1970's paint is immune to MEK, which takes the blue stains right off like magic.

I'd test with a swab on some spot under some trim/light/inspection panel and see if anything transfers.

Have been doing this for 15+ years on my non-removable blue stains with no perceivable negative effect. Have to do this much less frequently now that the tanks are re-sealed.
 
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