Tank access plate, nut plates?

So looking at the access plate and such i have a question just to make sure I’m not going to eventually explode in the sky one day. I couldn’t find the answer by searching. Ok so, when installing the 407 reinforcement ring in the tank rib, you are suppose to countersink it and dimple the rib web for the platenuts that will receive the 8r8 screws. My question is this….

If the purpose is for the rivets to lay flat for a seal of the T-708 and just to hold the nut plates for the screws, would it be ok/acceptable to use NAS 1097 3-4.5’s here and lightly COUNTERSINK THE RIB WEB to receive the tiny head of the 1097?

I did a test run on the piece I cut out of the rib and there was a very very good amount of material left after I countersunk for the 1097 head.

Thoughts???

Thanks you,

Yes it is, and it is what I would do.

Nearly every nut plate I install is done with NAS1097 rivets.
The only time I don't use them is in cases where the rivets mounting the nut plates are potentially transferring other loads such as attachment of a skin to a longeron, etc.

Interesting.

rvbuilder2002 said:

Yes it is, and it is what I would do.

Nearly every nut plate I install is done with NAS1097 rivets.
The only time I don't use them is in cases where the rivets mounting the nut plates are potentially transferring other loads such as attachment of a skin to a longeron, etc.

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That answers that. Thank you a ton Scott. Have a good rest of your weekend

rvbuilder2002 said:

Yes it is, and it is what I would do.

Nearly every nut plate I install is done with NAS1097 rivets.
The only time I don't use them is in cases where the rivets mounting the nut plates are potentially transferring other loads such as attachment of a skin to a longeron, etc.

Click to expand...

Additional context....

The kits come standard and are detailed in the manual, to use AN426AD3-X rivets.
There is a detail in Section 5 of the manual that mentions that NAS1097 rivets are an acceptable substitute when installing nut plates.
Use of NAS1097 rivets greatly speeds up the whole process because a shallow countersink for teh rivet head can be done very quickly and then a dimpled nut plate is not required (another potential time savings since only -08 nutplates are available pre-dimpled).
Another benefit is that there is no risk of a tipped (misaligned) nut plate. since the dimples in the nutplates do not form as well as they do on aluminum, they never nest fully flush on the surface they are being mounted on. This allows them to roll slightly if you accidentally tip the rivet when it is set. If the nut plate rolls, it will make the screw much more difficult or maybe impossible) to install. This unfortunately is often not discovered until much later in the build when it will be far more difficult to replace.

Beware

I used NAS1097 to secure most nutplates on my aircraft as many others but there are some locations I will not be using them again on my next build. The main one being single lug nutplates. These nutplates bend easily which cause misalignment with the screw and then the screw can't start. Any axial force on the screw also has leverage and quite easily can push the NAS rivets through their holes and now you got a mess on your hands. Ask me how I know... Reattaching seat pans in my plane is not a welcome experience due to this. haha I will be fixing them someday to avoid the headache. Otherwise the NAS method works great and is much faster!

Access cover nut plates

I didn't use any NAS 1097 rivets. However, I did use sealed nutplates on the tank access panel. No need to slather proseal all over the place because the nutplates are sealed from inside.

wirejock said:

No need to slather proseal all over the place because the nutplates are sealed from inside.

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;

Unless you want to make sure the cover doesn’t leak in the future
The gaskets are not reliable for the long term. That is why they are no longer supplied in the kits.

As for single leg nut plates…. I think 1097’s are just as reliable with maybe the exception being very thin material (.020). We have evolved the design standards to avoid single leg it plates other than cases where there is no other design alternative because of the bending problem that can happen even if they are riveted well.
I hate single leg nut plates.

Nutplates

rvbuilder2002 said:

;

Unless you want to make sure the cover doesn’t leak in the future
The gaskets are not reliable for the long term. That is why they are no longer supplied in the kits.

As for single leg nut plates…. I think 1097’s are just as reliable with maybe the exception being very thin material (.020). We have evolved the design standards to avoid single leg it plates other than cases where there is no other design alternative because of the bending problem that can happen even if they are riveted well.
I hate single leg nut plates.

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Not questioning the use of the NAS1097s. They are fine.
I also used proseal to seal the cover.
I'm just sayin the screws will never leak. It makes removal of the cover a little easier and eliminates a potential leak path.

wirejock said:

However, I did use sealed nutplates on the tank access panel. No need to slather proseal all over the place because the nutplates are sealed from inside.

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Totally agree with this, no leaks/seeps in 18 yrs. They will cost you a bit more than a standard nut plate though.