Steve White Fuel Tank Repair
From Bondline
Steve White contributed his story of the repair of leaking fuel tanks in his Traveler.
On Jan 3, 2006, I bought this 1974, 2-owner, AA-5 with 1441TT and 80hrs SMOH with HC. In the next nine months my wife says that I tried to see how much money I could spend on the airplane. She was wrong, but not by much. We put on new alt, starter, vac pump, electric fuel pump, all new hoses, tires, all DMA mods, RR cap, all antennas buried, Mitchell gauges, most instruments re-built, new transponder, new Sens prop - balanced also, paint, new interior, lots more, AND the right tank re-sealed. I was not involved in the re-sealing of the tank. Under the watchful oversight of my A&P - keeping everything legal, I replaced brakes, the Belleville washers, bearings, did new baffling, replaced the control bearings with the SS mod, re-rigged the control surfaces, replaced points and condenser/electronically timed the internal timing of the mags, re-installed the same, and on and on. I'm envious of Bob Steward and others who do this for a living. All this is to say, I really enjoy working on my plane. That is maybe I still do after twice into my fuel tank.
My A&P and I tackled it the first time, by the book. We did just as the two other fuel tank repair accounts: scraped forever and got everything super clean. This is the same tank that had been re-sealed just two years ago. None of the old material had been removed and the material we removed that was over the original sealer was the "low adhesive" material designated for usage on the access panels. There was a lot of gravel in this sealer. This sealing was done by a mechanic who no longer works at my IA's place. The mechanic took out the fuel sender unit. We worked together at night and then I worked alone for about a week at night and then he checked everything with flashlight and mirrors, we cleaned the tank and resealed with the 3207B (thick) sealer. Messy!! We checked the next night and saw places that seemed to need attention and resealed. I then checked the next night and even yet there was a place needing attention and resealed. He checked again and gave it his blessing. He let me re-install the fuel sender unit(new gasket, of course). I want to meet who ever designed those stupid grills that go on the outside of the bolts that hold the sender unit in. This job was never meant to be done. We filled the tank with five gallons and left overnight and no leak, five more gallons and still no leak. Then we filled it and left it overnight, and noticed a slight seeping. I just couldn't believe it! I wasn't ready to go back in. I flew it for three months.
Armed with more information from Bob S., Garner Rice, and Jeff Simon, the re-seal began. New equipment was used. A Milwaukee remote viewer, a web-cam/laptop, a dental spatula, and a hair drier greatly helped this process. They are pictured below:
First, the access panels just wouldn't budge. I used the small pointed instrument to remove the external adhesive but that didn't seem to help.
Then I tried the dental spatula to no avail. I was afraid I'd tear up my panel. Drove home and got a hair drier. I gently warmed the entire access panel to where it was warm but not hot and kept it warm for about five minutes. Then, I was able to ease the dental spatula under the panel. It works best at the beginning of the curvature of the panel. THIS IS A GOOD TECHNIQUE, IMO.
[IMG]http://img.photobucket.com/albums/v503/sewdds/03-01-09_1425.jpg[/IMG] [IMG]http://img.photobucket.com/albums/v503/sewdds/02-28-09_1649.jpg[/IMG] [IMG]http://img.photobucket.com/albums/v503/sewdds/02-28-09_1650.jpg[/IMG] [IMG]http://img.photobucket.com/albums/v503/sewdds/02-28-09_1609.jpg[/IMG] [IMG]http://img.photobucket.com/albums/v503/sewdds/02-28-09_1611.jpg[/IMG]
This was repeated three times, all panels off. The fuel sender unit was left in this time.
Now, I very carefully checked all bond seams by tapping with a half-dollar coin. I checked under and over the wing. This takes time, or at least I took a lot of time. My plane has purple sealer. No bond seam failure seemed to be present.
The drop light: [IMG]http://img.photobucket.com/albums/v503/sewdds/2009-04-01-80944.jpg[/IMG]
Now armed with the web-cam and a 13-watt energy saver bulb (produces very little heat) in a drop light, the inspection began. Was my A&P blind that night?! Was I?! No wonder it leaked. It all looked so good with the flashlight and mirror and so terrible with the drop light and web-cam and to a lesser degree of detail, the Milwaukee remote viewer. Look at these pictures of our "terrible" job.
[IMG]http://img.photobucket.com/albums/v503/sewdds/2009-04-01-77784.jpg[/IMG] [IMG]http://img.photobucket.com/albums/v503/sewdds/2009-04-01-78139.jpg[/IMG] [IMG]http://img.photobucket.com/albums/v503/sewdds/2009-04-01-78354.jpg[/IMG] [IMG]http://img.photobucket.com/albums/v503/sewdds/2009-04-04-78187.jpg[/IMG] [IMG]http://img.photobucket.com/albums/v503/sewdds/2009-04-04-78417.jpg[/IMG] [IMG]http://img.photobucket.com/albums/v503/sewdds/2009-04-04-78469.jpg[/IMG] [IMG]http://img.photobucket.com/albums/v503/sewdds/2009-04-04-78484.jpg[/IMG]
I had re-ordered type "B" 3207 and some more low adhesive sealer for the access panels. Also, I ordered some 3207 "A" , the low viscosity sealer like the factory used. I wish I had had it the first time. It will go into the other tank when that time comes. I used much smaller syringes(dental impression syringes) to place the "A" viscosity sealer. I love this stuff in comparison to the type "B" sealer. It all stinks and stains. It is SO messy! I also used some type "B" sealer in a few areas and then coated with the type"A". Next time : type "A" first, then "B" then "A". This will all be with inspections in-between each application. Here's what it looked like after all this:
[IMG]http://img.photobucket.com/albums/v503/sewdds/2009-04-01-78361.jpg[/IMG] [IMG]http://img.photobucket.com/albums/v503/sewdds/2009-04-01-78347.jpg[/IMG] [IMG]http://img.photobucket.com/albums/v503/sewdds/2009-04-01-78296.jpg[/IMG] [IMG]http://img.photobucket.com/albums/v503/sewdds/2009-04-01-80799.jpg[/IMG] [IMG]http://img.photobucket.com/albums/v503/sewdds/2009-04-01-80874.jpg[/IMG] [IMG]http://img.photobucket.com/albums/v503/sewdds/2009-04-01-80903.jpg[/IMG] [IMG]http://img.photobucket.com/albums/v503/sewdds/2009-04-04-78177.jpg[/IMG] [IMG]http://img.photobucket.com/albums/v503/sewdds/2009-04-04-78248.jpg[/IMG]
As you can see, the web-cam shows a much different quality of sealing. We just couldn't see this with the mirrors/flashlights. Then, I let it cure for 1 day and re-placed the access plates and let it cure for 3 more days. No leaks. When the other tank starts to leak, I will tackle this again without dread. My A&P said that I don't have enough money to pay him to do this the way it was done. Actually, he would do it and do it well; but I'd hate to think what the cost would be. He said, he'd prefer us to do it again just like "we" did this time: me work, he check and approve and me work some more. Here are a few finishing up photos:
[IMG]http://img.photobucket.com/albums/v503/sewdds/2009-04-04-81850.jpg[/IMG] [IMG]http://img.photobucket.com/albums/v503/sewdds/2009-04-04-84213.jpg[/IMG] [IMG]http://img.photobucket.com/albums/v503/sewdds/2009-04-04-85835.jpg[/IMG]
Here are some misc pictures: Outside of fuel sender unit: the bolts that hold it on: [IMG]http://img.photobucket.com/albums/v503/sewdds/2009-04-01-78953.jpg[/IMG] [IMG]http://img.photobucket.com/albums/v503/sewdds/2009-04-01-78605.jpg[/IMG] [IMG]http://img.photobucket.com/albums/v503/sewdds/2009-04-01-78576.jpg[/IMG]
This fuel sender unit - inside the tank: [IMG]http://img.photobucket.com/albums/v503/sewdds/2009-04-01-78390.jpg[/IMG]
The fuel scrubber line Bob S. can reach thru the fuel filler: [IMG]http://img.photobucket.com/albums/v503/sewdds/2009-04-04-78306.jpg[/IMG] [IMG]http://img.photobucket.com/albums/v503/sewdds/2009-04-01-78118.jpg[/IMG]
The fuel screens: [IMG]http://img.photobucket.com/albums/v503/sewdds/2009-04-01-79615.jpg[/IMG] [IMG]http://img.photobucket.com/albums/v503/sewdds/2009-04-01-80799.jpg[/IMG]
Though this is a picture taken a couple of years ago and before the "N"# change and (I'm happy to say) a few extra pounds ago, this picture depicts how a pilot feels and a plane looks after the leak is fixed. [IMG]http://img.photobucket.com/albums/v503/sewdds/untitled4.jpg[/IMG]
Summary of things I learned that haven't been mentioned previously:
- Hair drier helps immensely with removing access panels.
- A web-cam/laptop is all the remote viewing I need.
- Type "A" is easier for me to use 1st and third while type "B" would be used in-between.There may be good reasons to not do this, and maybe someone more knowledgeable will correct this assumption of mine.
- You can't check too much.
- Check to see if any de-bonding has occurred before any sealing begins: you may need both SK-125A procedures and sealing.
- A 13-watt energy saving bulb provides plenty of light and very low heat (to help protect the bonding), syringes are helpful for placement of both "A" and "B" viscosities. A paint brush helps with the "A."
- Paint thinner helps clean off the low adhesive flash.
- I actually kind of enjoyed this, but not enough to do your plane.
