Nutplates and Fuel Tank Sealant

CharlieWaffles · #1 05-12-2011, 10:37 AM

I?m wondering about the sealing process of the nutplate in the fueltank rib. I get the standard sealant under the nutplate and sealing the rivets like anything else, but specifically I am thinking about the threaded cavity. Is the screw/bolt providing sufficient sealing or is sealant added into the thread as the bolt/screw is inserted and tightened? The only other way I can think of doing a seal would be to create a sealant ?bubble? on the nut side that provides room for the screw to insert and go past the nutplate but not penetrate the sealant. That sounds a little far-fetched so I wanted to check how I should be doing this. Specifically it?s the nutplates and screw for the fuel senders.

beav · #2 05-12-2011, 10:44 AM

I upgraded those nutplates to NAS1473-A08 that have an integrated O-ring and a chamber on the back for the screw:

CharlieWaffles · #3 05-12-2011, 10:49 AM

Where did you get those from?

ccsmith51 · #4 05-12-2011, 10:54 AM

http://www.wicksaircraft.com/catalog...381/index.html

CharlieWaffles · #5 05-12-2011, 10:55 AM

Wow, that's one spendy upgrade/nutplate.

rocketbob · #6 05-12-2011, 11:09 AM

10+ years of flying with standard fuel tank covers (prosealed) with a dab of proseal on top of the screws, and never any leaks.

Tank rivets are another story.

beav · #7 05-12-2011, 11:26 AM

Quote:

Originally Posted by CharlieWaffles

Wow, that's one spendy upgrade/nutplate.

Only 0.1% of the cost of the plane :-)

jason

terrye · #8 05-12-2011, 12:39 PM

Yep, that's what I used.
Upside:
1. Made for the application and I'm sure they won't leak through the threads.
2. Much easier to remove the tank inspection cover in the future without proseal all over the screw heads.

Downside:
1. Expensive!
2. They still have to be prosealed on the tank side at the rivets.
3. The standard Van's fuel pickups (not the aerobatic flop tubes shown in the photos) interfere with the nutplates. I had to make a special bending tool to put a bend in the vertical portion of the fuel pickup tube.

CharlieWaffles · #9 05-15-2011, 08:40 AM

I'm going to be using the Princeton Electronics fuel senders (Capacitive) and wonder how the seal on the screw will work. Is this technique inserted the screw and the pro sealing the head of the screw? So it's not so much sealing the threads, just the head?

Walt · #10 05-15-2011, 10:38 AM

Quote:

Originally Posted by beav

I upgraded those nutplates to NAS1473-A08 that have an integrated O-ring and a chamber on the back for the screw:

I also recommend these nutplates, I used the -10 size so I could use a 3/16 hex bolts in place of philip screws.