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Fuel tank repair - 9a

wsquare

Active Member
Repairing leak in 9a fuel tank. Have the Vans repair kit with round panels and blind rivets. No instructions that I could find with the repair kit. Have found some web links that provide good guidance. Some sources advise to drill 4.5" holes and some sources advise to drill 5" holes, to access the interior of the tank. Is there any consensus on the recommended diameter, or perhaps official guidance from Vans?
Thanks, Wayne
RV-9a
 
Holes

Repairing leak in 9a fuel tank. Have the Vans repair kit with round panels and blind rivets. No instructions that I could find with the repair kit. Have found some web links that provide good guidance. Some sources advise to drill 4.5" holes and some sources advise to drill 5" holes, to access the interior of the tank. Is there any consensus on the recommended diameter, or perhaps official guidance from Vans?
Thanks, Wayne
RV-9a

I used the kit on my 9A. Make the largest hole you can get and still get the edge distance for the rivets. You will be doing all the cleaning and replacing of the proseal through this hole so bigger is better. I used a 5" hole saw. Mine was from a Starrett set but many have used the Harbor Freight saw. Resist the temptation to simply put a new larger fillet of proseal over the existing proseal. It will still leak. Don't ask me how I know...:(
Ed
 
4.5 worked for me

I used a 4.5" hole saw for a repair I did and access wasn't bad after smoothing the hole edge with a scotchbrite wheel. A tip I learned from another builder that was helpful (albeit not as comfortable) - Strap the tank firmly (just don't bend the tank skin) oriented baffle down on some saw horses and do the cutting, drilling, and sealing from under the tank on a creeper while wearing a face shield. Sounds crazy but the clean up for shavings is minimal and the extruded sealant that is pushed into the tank when you place and pull the pop rivets will fall back onto the pulled rivet shop head and not fall into the tank as "proseal snakes" This would happen if you did it in a cradle baffle side up with too much sealant.
 
What ever the edge distance between the rivet hole and outter edge of the cover plate should be the same between the rivet holes and the access hole edge in the tank. Don't scrimp the flange!
Place the cover plate on the tank, drill the rivet holes in place. Important- mark the cover plate and tank with a positioning mark so your holes align up again! ( you will find the rivet holes are not perfectly even & the cover will fit only one way)

Follow the build manual instructions/plans for sealing the tank.
 
Here's my writeup, well at least one of them...

You need a 5" hole.

I will also concur on the need to possibly remove and replace the sealant on the inside. Repaired another RV-9A tank that took three tries! Had to really dig down on one section to get it cleaned out enough to seal up where ever it was leaking - it looked completely sealed from the inside with a nice large fillet on the back baffle. Some of these leaks are cursed!
 
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Thanks!

Thank you for all the great suggestions. Also, I tried the writeup link, but was not successful in finding the content. Thanks again.
Wayne - 9a
 
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