Screw size for 1966 M20E wing root trim piece

[Cessna738]

Need to replace screws in the trim at the wing root. Can't find description in the parts manual. Nothing at Home Depot matches. 

[Fly Boomer]

1 minute ago, Cessna738 said:

Need to replace screws in the trim at the wing root. Can't find description in the parts manual. Nothing at Home Depot matches. 

First, what happened to the screws that came out?  Second, don't use Home Depot screws.  Someone who has documentation for an M20E will provide a more complete answer soon.

[mike20papa]

Originally they were #4 A thread sheet mtl. screws.  As time goes by .. owners/mechanics strip out the base metal so they no longer function.  So, #6's or larger are often installed.  The alternative to simply installing a larger screw requires a level of aptitude and resolve most are not capable or willing to associate themselves with.

[Kelpro999]

39 minutes ago, Cessna738 said:

Need to replace screws in the trim at the wing root. Can't find description in the parts manual. Nothing at Home Depot matches. 

Not only screws (#4flat head) but the Tinnerman type plates inside the fuselage 

[Kelpro999]

Just now, Kelpro999 said:

Not only screws (#4flat head) but the Tinnerman type plates inside the fuselage 

I’m having trouble finding the nut plates. They have bent up ends and allow a 5/16” wrench to hold or tighten from the back side. 

[Guest]

51 minutes ago, Cessna738 said:

Need to replace screws in the trim at the wing root. Can't find description in the parts manual. Nothing at Home Depot matches. 

From the IPC they are #4 x3/8” long, the Tinnerman nuts often fall off and fall behind the side upholstery when the screws are removed.

[PT20J]

1 hour ago, Kelpro999 said:

I’m having trouble finding the nut plates. They have bent up ends and allow a 5/16” wrench to hold or tighten from the back side. 

I don’t think anyone makes those anymore. I push small nails through the holes from the screw side and tape the heads in place with small pieces of duct tape. Then I place the Tinnermans over the nails on the other side and tape down with aluminum tape. Then I remove the nails and install the screws and the Tinnerman’s are held in place with the aluminum tape.

[Ragsf15e]

1 hour ago, M20Doc said:

From the IPC they are #4 x3/8” long, the Tinnerman nuts often fall off and fall behind the side upholstery when the screws are removed.

Clarence are there supposed to be tinnermans behind all those little screws holding that fairing on at the wing root?  I swear mine are straight into the sheet metal… but maybe that’s why they don’t hold well.  Are they clip on “U” tinnermans or the flat ones that are just on the back of the hole?  If the flat ones, how do you hold them on to install them?

I want to remove the fairing to look at my wing attach bolts again and spray some more lps3 on them, but I’m afraid of that fairing!

[Kelpro999]

42 minutes ago, Ragsf15e said:

Clarence are there supposed to be tinnermans behind all those little screws holding that fairing on at the wing root?  I swear mine are straight into the sheet metal… but maybe that’s why they don’t hold well.  Are they clip on “U” tinnermans or the flat ones that are just on the back of the hole?  If the flat ones, how do you hold them on to install them?

I want to remove the fairing to look at my wing attach bolts again and spray some more lps3 on them, but I’m afraid of that fairing!

[N201MKTurbo]

This is probably as close as you will get:

https://www.chiefaircraft.com/aircraft/hardware-fasteners/hd-a1776-4z-1-50.html?gclid=EAIaIQobChMInq2ft8Kb_QIV5QznCh0NeAG4EAQYASABEgLO3vD_BwE

 

https://www.aircraftspruce.com/catalog/pnpages/T4X6.php

[Cessna738]

Thanks for the help. I need to replace them because they are rusted and painted over. They didn't fall out. As a matter of fact, they were a pain to remove.  I noticed a fuel seepage that seemed to be under the trim. That is why I removed it. Good time to re-do the wing walk.

[Kelpro999]

5 minutes ago, Cessna738 said:

Thanks for the help. I need to replace them because they are rusted and painted over. They didn't fall out. As a matter of fact, they were a pain to remove.  I noticed a fuel seepage that seemed to be under the trim. That is why I removed it. Good time to re-do the wing walk.

Now that you have to remove interior side panels you’ll get a better visual on the fuel leak. When you put the root covers back on, use good sealing “duct” tape underneath them. Helps keep water out.

[Ragsf15e]

12 minutes ago, Kelpro999 said:

Now that you have to remove interior side panels you’ll get a better visual on the fuel leak. When you put the root covers back on, use good sealing “duct” tape underneath them. Helps keep water out.

And while you’re in there, the wing attach bolts are under the aft part of that fairing.  The duct tape mentioned above is supposed to keep them water tight, but they are often a little rough… maybe some corrosion x, lps 3 or whatever while you have it open.

[Guest]

10 hours ago, Ragsf15e said:

Clarence are there supposed to be tinnermans behind all those little screws holding that fairing on at the wing root?  I swear mine are straight into the sheet metal… but maybe that’s why they don’t hold well.  Are they clip on “U” tinnermans or the flat ones that are just on the back of the hole?  If the flat ones, how do you hold them on to install them?

I want to remove the fairing to look at my wing attach bolts again and spray some more lps3 on them, but I’m afraid of that fairing!

The IPC will show the numbers of screws versus Tinnerman nuts, but generally one to one.  You’ll need someone one the opposite side to hold them in place while you install the screws.  I’ve never been able to find the U shaped ones, so use flat ones where needed.

[BobbyH]

17 hours ago, PT20J said:

I don’t think anyone makes those anymore. I push small nails through the holes from the screw side and tape the heads in place with small pieces of duct tape. Then I place the Tinnermans over the nails on the other side and tape down with aluminum tape. Then I remove the nails and install the screws and the Tinnerman’s are held in place with the aluminum tape.

I love this, great idea.  I probably would have been playing two man hit and miss trying to get the tinnermans aligned up on the screws.  The aluminum tape will probably protect the tinnermans from some corrosion too.  There are probably many places, especially in the interior where this method will be handy.  Thanks.

[Ragsf15e]

17 hours ago, PT20J said:

I don’t think anyone makes those anymore. I push small nails through the holes from the screw side and tape the heads in place with small pieces of duct tape. Then I place the Tinnermans over the nails on the other side and tape down with aluminum tape. Then I remove the nails and install the screws and the Tinnerman’s are held in place with the aluminum tape.

I’m still trying to picture this… what are the nails for?  Just to see where each screw is going to poke through?

[N201MKTurbo]

3 minutes ago, Ragsf15e said:

I’m still trying to picture this… what are the nails for?  Just to see where each screw is going to poke through?

The nails will go through the tinnerman nuts and locate them. this way you don't need two people.

[N201MKTurbo]

If you were real anbusious, just mount A6195-4Z-1D nut plates to all the screw holes.

[Kelpro999]

8 minutes ago, N201MKTurbo said:

If you were real anbusious, just mount A6195-4Z-1D nut plates to all the screw holes.

-4Z-

[PT20J]

22 minutes ago, N201MKTurbo said:

The nails will go through the tinnerman nuts and locate them. this way you don't need two people.

EXACTLY 

[N201MKTurbo]

1 hour ago, Kelpro999 said:

-4Z-

Spencer aircraft shows them in their catalog, but not in their web store.

[Kelpro999]

3 minutes ago, N201MKTurbo said:

Spencer aircraft shows them in their catalog, but not in their web store.

Good, I’ve looked but haven’t seen anywhere, I’ll call them. That’s the answer for some other trouble spots also. Thanks for the info 

[N201MKTurbo]

3 minutes ago, Kelpro999 said:

Good, I’ve looked but haven’t seen anywhere, I’ll call them. That’s the answer for some other trouble spots also. Thanks for the info 

That number is for rivet on nut plates. If you just want the tinnerman nuts, you will need the flat ones.

[chriscalandro]

22 hours ago, Fly Boomer said:

First, what happened to the screws that came out?  Second, don't use Home Depot screws.  Someone who has documentation for an M20E will provide a more complete answer soon.

I only use Chevrolet certified screws in my El Camino 

[Kelpro999]

31 minutes ago, N201MKTurbo said:

That number is for rivet on nut plates. If you just want the tinnerman nuts, you will need the flat ones.

Yes rivet on and single lug would be great for some locations . A little time now saves 10x later