Proseal for the Fuel Sender

[JDA_BTR]

I'm finally getting to the end of my fuel tank assembly. I have followed the instructions to the T for the fuel senders, but I have a nagging doubt.

When the nutplates are installed in the end rib no proseal is needed because the bed of proseal on the end under the sender will seal them. But what makes the screw holes sealed? There aren't any particular instructions for that, and I didn't get any proseal up through the sender holes and around the heads outside the tank.

I know that the screws got proseal on them when I sent them through the holes because they had to pass through my bed of proseal on the rib. But was it adequate?

Did anyone cover the nutplates and screw ends on the inside of the tank with proseal? Am I overthinking this? Will the thin band of proseal on the screw as it enters the nut plate threads take care of this?

 

[wirejock]

Screws

A dab on the area where the head makes contact should do. Some cover the screw completely. I used sealed floating nut plates. No need to seal screws.

 

[bddalm]

Proseal

If you put the screws in wet (proseal around the threads near the head), this should make a good seal.

 

[sblack]

I am planning on using a thread sealant. I understand that others have gone that route successfully. I am also using socket head cap screws so that I can get some torque on the screws to overcome the effect of the sealant if I ever have to open the tank. There isn't much room to get a screw driver in there once the aurplane is assembled.

 

[David Paule]

Even with self-sealing nutplates, it's worth sealing the head of the screws. One leak path is between the hatch and the rib to the thread and then out under the head.

Incidentally, I used access hatch sealant for the tank hatch and the parts mounted on it.

Dave

 

[jeffw@sc47]

what are these?

A dab on the area where the head makes contact should do. Some cover the screw completely. I used sealed floating nut plates. No need to seal screws.

what are 'sealed floating nut plates"?

 

[wirejock]

Nutplates

what are 'sealed floating nut plates"?

These.
http://m.skygeek.com/national-aerospace-standard-nas1473a08-nutplate-st.html

They are sealed. There's a rubber seal where they mate to the flange but I prosealed them as well. No hole so pick a screw that won't bottom out. The nut floats unlike a typical nutplate is all one piece.

 

[Mike H]

These.
http://m.skygeek.com/national-aerospace-standard-nas1473a08-nutplate-st.html

They are sealed. There's a rubber seal where they mate to the flange but I prosealed them as well. No hole so pick a screw that won't bottom out. The nut floats unlike a typical nutplate is all one piece.

Those are referrred to as "dome nuts"

 

[wirejock]

Dome nuts

Those are referrred to as "dome nuts"

Learn something new every day.
I used dome nuts.