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Fuel Tanks

posted Nov 9, 2011, 12:18 PM by Bill Thomasson   [ updated Dec 29, 2011, 12:03 PM ]
Part Started: 9/15/2011
Part finished: 12/11/2011
Time : 90.5
Changes from plans:
  • None
 Great writeup on how to proseal your tanks
Basics of how I did most of my tanks, coat the ribs with proseal and cleco them in (every hole).  Then let the proseal setup a day (or more) before riveting.  Then put a dab of proseal in each rivet hole with a Q-tip, followed by a rivet.  I would dab enough holes that I could rivet in about 1 hr, then insert rivets in those holes, change to clean gloves, and then rivet them.  Only the hand with the bucking bar would get proseal, along with the bucking bar and the flush rivet set.  Then wipe down the skin, bucking bar and flush rivet set with acitone and start the next batch of rivets.  Overall it was not as bad as I expected, but does take a lot longer.  No leaks in the pressure test.
Fuel tank initial fit and match drilling
Prosealing the stiffeners and backriveting.
 Prosealed over and riveted plates over tooling holes and nutplates.
Riveting done except back baffle.  Vent line is in, and proseal slathered on external joints.
Before putting the back baffle on I filled the tanks with water (with water balloons over the fuel and vent lines) to check for any leaks.  One tank was fine, the other had a steady drip out of one of the tooling hole covers.  Drained the tank (with a wet/dry vac) and then coated the inside of the tooling hole cover with proseal again.
Added proseal to all surfaces about to put the back baffle in place.  I used a ziplock back with a corner cut out to apply the proseal lines.  Everywhere else I had just used a popsicle stick.
Tank done!  After 2 weeks, put a balloon over the fuel outlet and ziptied on.  Filled the tank from the vent line, then when the balloon was full put a small water balloon on the vent line.  Covered the tanks with soapy water.  Only bubbles came from the drain, and from around the fuel outlet fitting.  I removed these and put a little Fuel Lube on them then snugged them back down.  With the fuel lube they tightened much further into the fittings, and no leaks of air.  The balloons were still inflated 2 weeks later when I had to pop them to get them out of the way to put the aileron pushrods in.