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Date: Thu, 15 Aug 2013 10:29:54 -0400
From: Ernest Christley <echristley@att.net>
Reply-To: echristley@att.net
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Fuel tank repair
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The Delta has one ~50gal tank that sits behind the back seat.  Not 
wishing to fight the compatibility issues between epoxies and whatever 
the government may mandate be put into our fuel supply next year, I went 
with an welded up aluminum tank which I epoxied into the turtleback.

For fittings, I welded in two NPT adapter bungs to the bottom of the 
tank.  One for fuel supply, and one for return.   I had a small, seeping 
leak at the supply fitting. I needed to turn the NPT-to-AN6 90 degree 
adapter one more turn to make it seal.  I got it most of the way around 
before I heard a sharp ping.  The bung that I welded in is now split.  
And that split is guaranteed to expand with vibration.

The only solution I can think if is to cut a round hole to remove the 
bung, and then construct two plates (one for the inside of the tank and 
one for the outside), with a hole in the center for the 90 degree 
adapter.  The problem is, the tank can now be viewed as a bomb.  How can 
I cut a hole in the bottom of the tank, which will require that I work 
in an enclose space, without the possibility of a spark making short 
work of everything?