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Looking for fuel tank removal steps

Gash

Gash

Well Known Member
I have a small fuel tank rivet weep and will be removing the tank tomorrow for a bit of Loctite repair on the offending rivet(s). I haven't had to remove a tank yet, and have searched unsuccessfully for step-by-step tank removal instructions, points to ponder, things to not screw up, and other general ideas.

If you've been down this road before, could you please tell me what to look out for? I don't want to make a small problem a big one by doing something bone-headed. Thanks.
 
The leak seems to be coming from the outboard side of the left tank, since that's where the blue stain is showing up. I can't tell if it's the forward or aft area of the outboard tank wall. The blue stain is just coming from that side of the tank "someplace."

I don't have a photo right now, but I can get one when I go back to the hangar tomorrow.
 
I've had mine off a few times and can't think of any particular tricks. By memory; drain the tank by removing the quick drain valve, disconnect the fuel line edit (and the vent line), disconnect the fuel level sender wire, remove the forward support bolt and start removing screws in whatever order is convenient.

Don't worry about the tank falling off. It may take a bit of persuading after all the screws are removed.
 
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I had a tiny leak last summer. It took about an hour or so to remove the tank. It wasn't a very big deal, a lot easier than I thought it would be actually.

PM me if you'd like a step by step of how I did it.
 
Battery

Remove battery ground from battery before working. Just a safety precaution even though the sending unit is low voltage and probably won't have power going to it..... Unless kitty accidentally flips master switch and a spark or static charge ignites those fuel fumes that was just drained.....
 
On the RV-8, in addition to the screws, you will have to remove a gaggle of AN-3 bolts that attach the tank to the spar. You can access them from the inspection panels and at the the inboard end of the wing.
 
What has already been said. If you are painted, you will want to use a paint cutter to score the paint around the screws so it doesn't take chunks if paint out with the screws. The bolts are an adventure sometimes, but are doable. A shirt ratcheting wrench is a handy tool for pulling these bolts.

Make sure your fuel selector is on the opposite tank. Drain tank by removing quick drain.

Disconnect fuel sender wire, fuel line to fuse & vent. Best to cap both sides of these so little nasties don't get in there while the tank is off.

Make sure you have proseal available so you can reseal any leaks if you find any on the rear spar.

Remove forward "spar" bolt.

Leave a couple of screws in to make sure the tank doesn't fall off after all other attachments have been removed. As was said, the tank will likely need a little persuasion to come off anyway, but the screws as a precaution.
 
Thanks very much for the replies guys. Looks like not a big deal to get the tank off...getting to the AN-3 bolts will probably be the most excitement involved. I'll let you know how it goes.
 
Before removing the tank and risking an unnecessary scratch or dent, I would invest an hour or three more looking for the leak. You can drain the tank and perform a leak test with it on the plane. you may be able to find and fix the leak through the inspection plate.
 
When I pulled a tank on my -4, I used thin plastic sheet & Popsicle sticks to lift the flanges away from the spar, to prevent the dimples dragging across the spar flange. Might have been overkill, but I didn't want to scratch the flange. I did it alone, but a 2nd set of hands would have made it a lot easier to support the tank while the last screws come out, and to stabilize the removal.

Charlie
 
Count the AN-3 bolts!

Removing all the AN-3 bolts that attach the tank Z-brackets to the spar is not difficult but you can't see some of them through the access holes in the bottom of the wing. You have to feel for them. Be sure to count them as you remove them. There are seven Z-brackets with three bolts in each. Make sure you remove all 21 bolts!

Oh, and put all 21 back when you are through. :D
 
Gash said:
Thanks very much for the replies guys. Looks like not a big deal to get the tank off...getting to the AN-3 bolts will probably be the most excitement involved. I'll let you know how it goes.
Click to expand...

No, the most excitement will be retrieving the AN-3 bolt that you dropped, after it slides down the wing skin and is sitting against the rear spar.
 
Tank Removal

I made some duct tape "dams" or "fences" in the wing before removing bolts (or rivets depending on your intentions) to keep dropped items from rolling back in the wing to the aft spar and being hard to retrieve. The duct tape (or poster board and duct tape) dams prevent items from being able to roll back very far.

Also, I did have to "disengage" the dimples in the skin form the mounting flange (on my RV4) before the tanks would budge. I used thin strips of aluminum and protected stuff with masking tape. Thin strips of lexan (4" wide as long as the tank -to insert between the tank and the spar) would probably be less likely to scratch and scrape than the aluminum I used.
 
If you have removed all the bolts thru the inspection holes and only have 18 bolts, there are three more at the far inboard part of the tank. You will need about an 18? extension and socket to remove them from the leading edge inboard area where you disconnect the fuel line.
 
I have removed my right tank a couple times. (Last time I sent it to Weep no more and now NO leaks). Anyway one thing I did last time that made a world of difference was to remove the bolt holding the aileron push rod in place. When it's hooked up, it sits just infront of the lower, (I think), bolts leaving only an inch or so to get at them. If you remove aileron pushrod bolt at the bell crank end wrap a rag around it and move it aft far as possible. It made the most difference when trying to get at the bolts that are above the wheel pant and inboard from there. And like Homie said above, don't forget about the three you'll access where the fuel and vent lines are!!!
 
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Tank removal

In my limited experience, proseal has a tendency to migrate to the main spar from the rear baffle. a thin putty knife may be necessary to slip along the spar to separate the tank flange. Good luck
 
This is good to read. My left wing tank has a leak coming out of the sending unit seal. I picked up some seals yesterday from Aircraft spruce to replace it, I figure I'll do the job over a long weekend instead of a short one. I'd rather not use proseal on the entire sending unit cover in the event I need to replace the sending unit in the future. It sounds like removing the tank shouldn't be terrible to do. I just hope this seal doesn't leak after doing the repair. That would suck!

- Gabriel
 
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