Fuel tank covers and inspection covers screw lenght

[Gerhard Rieger]

Hi everybody, Those who are already past this stage, can you tell me what the lenght of the #6 stainless screws was that you used for your cover plates?

[Ed.Meyer]

We used 3/8 inch length. Will be switching to cad plated rather than stainless as they are removed because the stainless screws gall and heads strip so easily.

[jaredyates]

Same here, cad plated 3/8.

[tailwind]

Stainless looks nice. They gall as indicated above. I even tried a small drop of lube on each screw, still no joy. Also if you drop one where you do not want it you can’t recover it with a magnet. 3/8 cad plated for me now.

[svyolo]

SS screws and SS nylocs should be outlawed. The bigger they are, the worse they are. I had a couple gall on the first install. A couple of threads at a time, and let them cool. They still welded together.

[Gerhard Rieger]

Thanks for the advice I ordered the cat/plated screws 3/8 long. have fun building

[Collin Campbell]

Interesting comments…my experience has been somewhat different (perhaps not the most popular it seems…lol) though. I have used stainless screws in all the inspection plates/access covers in all three of my Bearhawk projects. The covers have been off/ on MANY times and I have never had any problems with galling/seizing. In searching the RV builders archives I find that many others have had the same experience with no issues.
If you do use stainless screws, here are a couple of things to consider: I always use “Easy Turn” lube on the screws (like you use on all the aluminum AN fuel fittings…) I have heard that some like to use the wax from a toilet gasket, but have never tried this myself. Use a toothpick and put a small drop in each nutplate. Also I NEVER use power equipment to install/remove the screws…carefully hand drive them. Less heat buildup that way. Some have even recommended running a tap partially through the nutplate to remove some of the friction due to the locking/clamping feature. I have found this to be helpful on the monadock clip nuts I use on the floorboards…they seem to have a LOT of friction no matter what kind of screws you use! Just my thoughts…here is a link with some points to consider…

http://www.atlanticfasteners.com/tech-tips/how-to-stop-thread-galling-on-stainless-fasteners/

Collin

[svyolo]

Working on the last few things before I close the wings. I noticed the tank bay holes drill at the factory are not dimpled like the rest of the bottom wing skin. Nor are the skins. Obviously they still can be but is the intention to use non-flathead screws?

[jaredyates]

Working on the last few things before I close the wings. I noticed the tank bay holes drill at the factory are not dimpled like the rest of the bottom wing skin. Nor are the skins. Obviously they still can be but is the intention to use non-flathead screws?

Unless the model B is different than the original, I'd countersink the wing skins, dimple the cover, and use 3/8" or 5/16" screws. That's not any official answer, just the way it is done on mine.

[way_up_north]

Interesting comments…my experience has been somewhat different (perhaps not the most popular it seems…lol) though. I have used stainless screws in all the inspection plates/access covers in all three of my Bearhawk projects. The covers have been off/ on MANY times and I have never had any problems with galling/seizing. In searching the RV builders archives I find that many others have had the same experience with no issues.
If you do use stainless screws, here are a couple of things to consider: I always use “Easy Turn” lube on the screws (like you use on all the aluminum AN fuel fittings…) I have heard that some like to use the wax from a toilet gasket, but have never tried this myself. Use a toothpick and put a small drop in each nutplate. Also I NEVER use power equipment to install/remove the screws…carefully hand drive them. Less heat buildup that way. Some have even recommended running a tap partially through the nutplate to remove some of the friction due to the locking/clamping feature. I have found this to be helpful on the monadock clip nuts I use on the floorboards…they seem to have a LOT of friction no matter what kind of screws you use! Just my thoughts…here is a link with some points to consider…

http://www.atlanticfasteners.com/tech-tips/how-to-stop-thread-galling-on-stainless-fasteners/

Collin

with the success you've had, do you think it might be careful torquing. is there an inch pound rating for these.

[svyolo]

My hardware kit came with about 500 non countersunk screws. Still not sure if that was a mistake, or all the external inspection covers and most others are not countersunk/dimpled. I would rather they be flush.

[tailwind]

I see a difference in application. I install them by hand. I have never lost one during installation. I use a power screwdriver for removal. It makes sense that it would generate more heat with the power screwdriver and I lose them during removal. I still can’t pick them up with a magnet when they fall where I don’t want them. They do look good.

[Isilverone]

I used SS on all of my covers and learned the hard way to lube em. When removing, I break them loose with a screwdriver and then use a power screwdriver the rest of the way out. I used a very small drop vaseline on them at the start and have had no issues since.

[Battson]

I found stainless caused a lot of dissimilar metal corrosion on the aluminium. Switched to cad-plated and it stopped almost immediately.

[svyolo]

I have used a large amount of SS and nylocs on boats. The smaller the better, or maybe a better description is the bigger the worse. 1/2" or bigger, a couple turns and then stop and let it cool. I considered them 1 time use, and if you had to remove them, replace them. Half the time you had to remove them with a grinder and cutoff wheel.

6-32 or 8-32 isn't as bad. I think the screws that will rarely be removed will be SS. The ones that will be removed routinely will be CAD plated. I wish I could find some 100 degree hex or star drive flat head screws but so far no luck.

I was also a maintenance officer in the USMC. Side job to being a pilot. The plane I flew was held together with hundreds of flush (hex drive if I remember) screws. No power tools allowed, or on site. They used hand augers only. I don't know what the fasteners were made of. They could swap a motor in 20 minutes, and I think 15 of those were external fasteners.

SS and friction lock are a bad combo, but 6-32, occasionally used is OK I guess.