You know how, on light aluminum airplanes, fairings are attached with a screw which simply screws into the bottom sheet of metal, no fastener? And you know how little torque it takes to strip the threads out? The easy fix is to increase the size of the screw or drill a new hole, but are there any elegant options for repair?

Uh, don't tell me "duct tape." I know it's available in blues and yellows that match really well.

you can install nutplates if you can get to the back side to rivet them in. if not rivnuts will work as long as you dont put too much torque on the nuts. If you do then the rivnujt just spins with your screw and you are screwed (pun intended)

Don't forget the mighty Tinnerman nut.

mr scout wrote:Don't forget the mighty Tinnerman nut.

God bless Mr. Tinnerman. I think my 170 has more Tinnerman nuts than original unadulterated screw holes.

I have put in quite few nutplates on my plane without having to access the back side. Often you can pull them into place with a string or wire through the screw hole to an opening, then hold them with a long screw and use small flush pull rivets. I have also put in smaller sized nut plates thru the over sized hole itelf. There is a big variety of nutplates, do look in the handbook or a catalog.

Some times you can use a Tinnerman. Some are U shaped and clip on the opening, others are an arched plate and hold by compression. A slim one might fit in the (now) cleaned up oversized hole. Remember these are all designed for aircraft screws, hardware store screws have a slightly different size and thread.

BTW on my Cessna, at least, no screws were just put into an aluminum sheet.

Where there is a need there is a way!

mr scout wrote:Don't forget the mighty Tinnerman nut.

Of course! Those are great. The clip kind would "probably" work just fine, although it puts another piece of metal in where parts are better off aerodynamically mating flush.

The kind without the clip would be great, if I could find some way to hold it in place. With good surface preparation, chances are that a few dabs of MIL-SPEC crazy glue would do the job if some metal took the torque.

Is there something else with Tinnermans that I'm not seeing? I haven't used them much, probably misused them when I did, long ago and far away.

I noticed that extra metal was flush-rivetted on where my cowl attaches. I'm glad to see I don't have to go that route!

you can also red or blue locktite the rivnuts, they will stay that way.

B&Y,

I feel your pain! That is the one thing that Don Luscombe should have done something about. Can't tighten the wing fairing screws enough to keep them from coming loose, thus they have to be tightened before every flight.

Increasing the screw size just allows for that screw to eventually strip out then you are royally screwed

It would be really tough to get a nutplate into many of the places where they would be needed, and it would take a lot of them.

If you find a good fix let me know.

Jon

i used to have duct tape holding a inspection cover and and a window shut; the silver matched the polished aluminum pretty good.

Instead of rivnuts, use gripnuts. They are a rivnut with serrations in the collar so they have teeth to help from spinning. Other than that they are the same.

If you go with timermen there are differences in the screws that you SHOULD use. The screws are blunt ended and have a slightly different pitch to them. they will work if you use pointed end screws, but they can work out a bit easier.

As I recall sitting here with out a catalog they are a and b points.

For the little cost difference get the better plated or ss screws as they look better with time.

I have used them on my Stinson with very good results.

Good luck

whee wrote:Can't tighten the wing fairing screws enough to keep them from coming loose, thus they have to be tightened before every flight.

For that, you could maybe back them out, gloop in a little silicone sealant, and tighten them up, so long as the screw is holding something. Once dry it'll hold the screw in until annual time when you pull it out, inspect everything, and redo it.

I'm screwing around back by the tail. I took the two fairings off and forgot which screw went in where, so some aren't grabbing anything, anymore. It's obnoxious when they're all different sizes, but when they're different pitches, too...

So I think I'm going to get an assortment of tinnermans and a tube of crazy glue, and experiment with bending the tins to fit and keep from turning, and then gluing them in place. I suspect it won't go exactly as planned. You're right that some of the places will be downright hard to do this with.

My mechanic's an old aluminum guy, he'll probably have a better idea.

Blue&Yellow Luscombe wrote:My mechanic's an old aluminum guy, he'll probably have a better idea.

His better idea: forget the tinnerman and use a piece of scrap aluminum with a small hole drilled in it and glue it to the back. He wins no points for overkill on longevity, but many points for keeping it simple.

An excellent glue would be fuel tank sealant. Most call it B2 or proseal. Very strong bond and flexable. http://www.aircraftspruce.com/catalog/c ... roseal.php
Get on drop of this stuff on your fingers and you will ruin all of your clothes, acetone will remove it when it's wet from fingers etc., but not clothes.