Cool tools ?

Best extractors I have ever used: http://www.matcotools.com/catalog/product/SEXS25/25-PIECE-SCREW-EXTRACTOR-SET/

When I would be opening up a plane for annual, I had a second drill motor set up with the proper bit for the one I use for #8 & #10 size screws and one of those extractors in a short socket with a 6" extension and short quarter drive ratchet for dealing with stripped screws. Once I worked out that rig my productivity opening up planes went way up. No matter what, a stripped screw head is 7 seconds to remove the screw. If I know I'll have a bunch, I'll predrill them all and then stick it in the socket with Seal Lube and put a 1/4" drive speed handle on it. Just use a set stop on the drill, it's faster than even bothering with the screwdriver bit. I used to make people a deal; when they brought their plane in for annual, if they went down the street a block to Cherry Street Fasteners and pick up an airframe screw kit from them, I would change out all the screws and it wouldn't cost extra.
 
how do you remove a machine screw that is seized in a rivnut which has become loose - and you cannot access the back side.
the screw and the nut spin together happily, either direction with a screwdriver, drillbit or ease-out. You must not damage the metal surrounding the screwhead.
 
Let'sgoflying! said:
how do you remove a machine screw that is seized in a rivnut which has become loose - and you cannot access the back side.
the screw and the nut spin together happily, either direction with a screwdriver, drillbit or ease-out. You must not damage the metal surrounding the screwhead.
Click to expand...

Get some 3M 5200 and get it packed into the mating flange between the rivenut and backing as best that you can and let it cure. That should hold it to drill, but you have to provide a bit of cooling or stop drilling momentarily to control the heat so you don't release the 5200 until you're done. Drill gently as well preferably with an air drill if you have one. Electrics have enough torque that a bit grab on a burr can tear the 5200.
 
Last edited:
Tom,

Your question is one reason that I really despise rivnuts; they're a cheap way of not doing the job right in the first place. That said, there are ways to deal with the problem.

If you can get to the rivnut head itself, below the screw, sometimes you can snag it with vice grips or find a way to pin it in place with the edge of a cold chisel. Much of the time, however, it's concealed beneath the panel you're trying to remove, and all you can access is the screw head itself.

Sometimes you can put enough pressure on the panel, without marring or damaging it, to hold the rivnut still long enough to get the screw clear. Sometimes you can improve the situation a bit with a shot of Kroil and letting the parts sit for while before you try again. Failing that, sometimes the next best course is to remove the screw head. If you can get on the edges of the screw with vice grips or another tool to hold the screw in place, you can use drill bits to remove the head in the same way you'd do the shop head on a rivet.

Once the screw head is removed, you can get the panel off, then access the rivnut head, and sometimes the back of the rivnut.

There are a number of ways you can remove the fastener at that point without damaging any of the nearby surfaces, using your vice grips and other tools.

Once you get rid of that rivnut, find another type of fastener to do the job, such as a nutplate. You'll be glad you did because rivnuts cause nothing but headaches in the long run.

If you have to use a rivnut, get some PRC sealant behind it to help prevent it from eventually loosening and spinning, and use the sealant when you're putting it in in the same manner you'd drive a rivet "wet."
 
DouglasBader said:
Tom,

Your question is one reason that I really despise rivnuts; they're a cheap way of not doing the job right in the first place. That said, there are ways to deal with the problem.
Click to expand...

Problem is welding a rosette into sheet metal, especially aluminum is time consuming and tricky as hell. You need a $35hr person (many markets they'll be higher) to do it where as you can hand a Rivenut gun to a minimum wage kid with no experience.
 
Henning said:
Get some 3M 5200 and get it packed into the mating flange between the rivenut and backing
Click to expand...

nuh-uh, the screw head is still holding the fairing or other sheet over the top of the layer that the rivnut is attached to, can't gain access to the rivnut top either!
I hate rivnuts. The only time they turn loose is when the screw seizes, and that is when you need them to really, really hold tight.
 
Doug's idea of removing the screwhead is the only way I know, risks damaging the surface and you still have the problem of the rivnut and cutoff screw inside it.
I hate rivnuts. Oh did I say that? Rivnuts should be illegal, there that's better.
 
Let'sgoflying! said:
nuh-uh, the screw head is still holding the fairing or other sheet over the top of the layer that the rivnut is attached to, can't gain access to the rivnut top either!
I hate rivnuts. The only time they turn loose is when the screw seizes, and that is when you need them to really, really hold tight.
Click to expand...


Get out the grinding tools and man up. If you're not real confident, a roll of duck tape will be your best friend. If you do it well you will damage no surrounding materials.
 
Some times a thin screw driver or knife can be inserted inbetween the panel and the rivnut. Adding a little tension can help to release the screw.
 
Can you grab the edge of the screw and drill the head off? Otherwise, start drilling rivets.
 
Left handed drill bits are my favorite. Used to have to remove
Hawker leading edges with those terrible British slot screws, I would end
up drilling 30 to 40 out every time. Left handlers would take all but 2 or 3 out.
Dave
 
Let'sgoflying! said:
how do you remove a machine screw that is seized in a rivnut which has become loose - and you cannot access the back side.
the screw and the nut spin together happily, either direction with a screwdriver, drillbit or ease-out. You must not damage the metal surrounding the screwhead.
Click to expand...
Remove the head with a dremel tool and a diamond burr.
 
Your suggestions are correct, or in agreement with what I have found: carefully remove head, otherwise you are going to damage the top sheet. If you grind it off, have to be careful the heat doesn't get the paint.
Then you have a rivnut with a screw shank left in the bottom sheet.
Maybe you can get that screw out and reseat the rivnut....or maybe there is no &%$ way it will come out and you have to do the same or similar to the rivnut/shank as you did to the head, push it in and replace with a new one.
Not a common scenario but if you have done a few of these you remember it.

How about those Cessna tank cover phillips screws that are corroded in place?
 
Let'sgoflying! said:
Your suggestions are correct, or in agreement with what I have found: carefully remove head, otherwise you are going to damage the top sheet. If you grind it off, have to be careful the heat doesn't get the paint.
Then you have a rivnut with a screw shank left in the bottom sheet.
Maybe you can get that screw out and reseat the rivnut....or maybe there is no &%$ way it will come out and you have to do the same or similar to the rivnut/shank as you did to the head, push it in and replace with a new one.
Not a common scenario but if you have done a few of these you remember it.

How about those Cessna tank cover phillips screws that are corroded in place?
Click to expand...


Bite me;)
 
Skylane81E said:
Bite me;)
Click to expand...

I have done a couple covers and the last one, I made every screwhead into a slot with the dremel tool.
Phillips heads = fast, easy to use, but Slot heads = greater available torque.
Got out all but I think 6, had to drill those heads off.
No biting required!
 
Henning said:
Impact driver and a 32oz dead blow ball peen hammer.
Click to expand...

You might get away with that on the spar although even that would be scary, but many of them are supported only by a rib - hammering would deform something. No way to reach in there to get below with a heavy block if the tank is still in place.
 
How about those Cessna tank cover phillips screws that are corroded in place?
Click to expand...

Soak them with Kroil first.

It's counterintuitive, but try tightening them slightly if they're not backing out. Often you can break them free by slightly tightening first, and they'll back right out.

Use the right tools. If there's question on the purchase of a phillips bit, put some valve grinding compound on the bit, first. A long screw driver angled slightly will often bring a screw out, with some pressure, when a shorter one presents difficulty. Use a speed handle with some shoulder pressure and try angling the bit slightly. It helps.

Before you go to easy-out land, there's always an old-man and a 3x rivet gun. Be careful on delicate structures.

The biggest sin I see with screws (aside from people who try bone-headed moves like sticking PK screws in nut plates) are those who use electric screw drivers or screw guns, and don't understand the clutch concept, or how to stop once the screw is down. People driving them in so tight they won't come out except with a nuclear device are one of the primary reasons we end up with stripped screws in the first place.
 
They're nice when one has a lot of screws to remove. A few months ago I was involved in a heavy maintenance check on a C-130, and had to pull all the flooring in the cargo area. That's a LOT of screws. Presently I use a lightweight 12 volt from Craftsman, and really like it. It goes a lot time, has a lot of torque, has a lot of settings and high and low to boot, as well as a light. It's been great.

I do think that people tend to overdo screw guns, however.

What really made a difference for me were palm racheting screw drivers from snap-on. I've got a bunch of them, and they make an enormous amount of difference in the way my wrist reacts early in the day. I also get a better bite on stubborn screws, and it's easier to bear down on or angle into the screw.
 
Let'sgoflying! said:
You might get away with that on the spar although even that would be scary, but many of them are supported only by a rib - hammering would deform something. No way to reach in there to get below with a heavy block if the tank is still in place.
Click to expand...

Operator skill. The reason I use a 32oz dead blow is I have finer control. The impact driver has a spring I have to load through, so I want low reflection energy for follow through. With a 32oz dead blow and my Snap On impact driver, I can minimize my swing force/head speed which allows me finer control and gives me the requisite energy to trigger the hammer while minimizing the vertical shock. The trick is to swing just hard enough to trip through the spring.
 
Last edited:
DouglasBader said:
They're nice when one has a lot of screws to remove. A few months ago I was involved in a heavy maintenance check on a C-130, and had to pull all the flooring in the cargo area. That's a LOT of screws. Presently I use a lightweight 12 volt from Craftsman, and really like it. It goes a lot time, has a lot of torque, has a lot of settings and high and low to boot, as well as a light. It's been great.

I do think that people tend to overdo screw guns, however.

What really made a difference for me were palm racheting screw drivers from snap-on. I've got a bunch of them, and they make an enormous amount of difference in the way my wrist reacts early in the day. I also get a better bite on stubborn screws, and it's easier to bear down on or angle into the screw.
Click to expand...
I have the same drill, tend to use it for almost everything, even wheel disassembly for tire changes, zip it apart, change the tire and zip it together, hit it with the torque wrench and inflate.
 
Simply use a Speed handle with a Snapon ACR #2 apex tip, and the ones that won't come out, use a #30 split tipped drill to remove the heads then after the cover is off you can grab the screw with vice grips. and remember when you replace the cover, use Nickel antiseze
 
Skylane81E said:
The cheap grabbits work well on the tank covers
Click to expand...

+1

Also +1 on cutting a slot in the head.

And I think Cherokees are the worst about the tank screws being a pain.

But at least you can get to the back side of all of them after you end up drilling off the head.
Unlike the C-150 tank cover. Where the only ones you end up having to drill the heads off of, are behind the rear spar. :mad2:
 
Tom-D said:
Simply use a Speed handle with a Snapon ACR #2 apex tip, and the ones that won't come out, use a #30 split tipped drill to remove the heads then after the cover is off you can grab the screw with vice grips. and remember when you replace the cover, use Nickel antiseze
Click to expand...

We still talkin' Cessna tank covers? IIRC there's several screws that cannot be had from the backside. (along the rear spar comes to mind) and those are usually the ones needing the heads drilled off.
 
bluerooster said:
We still talkin' Cessna tank covers? IIRC there's several screws that cannot be had from the backside. (along the rear spar comes to mind) and those are usually the ones needing the heads drilled off.
Click to expand...


If you take a 4" set of vise grips and grind the tip back with a wet stone (or mill if you got one handy) and make a flush flat tip +/- 1/32" and trim the sides a bit; there is usually enough left on the front side, if you are delicate about drilling the head, once you remove the material it was holding. If you wanna be really slick, grind a small ellipse into the jaw so there's just 4-1/32" squares at the tips and 1/32" gap in the middle.
 
Last edited:
Let'sgoflying! said:
Your suggestions are correct, or in agreement with what I have found: carefully remove head, otherwise you are going to damage the top


Then you have a . . . shank left in the bottom sheet.

....or maybe there is no &%$ way it will come out and you have to do the same or similar . . .as you did to the head, push it in
Click to expand...


Hmmmmmm. Sounds technical.
 
kimberlyanne546 said:
Hmmmmmm. Sounds technical.
Click to expand...

We are actually talking about a large part of expensive annuals.:rofl::rolleyes2:

Seriously though, one stripped fastener can cost hours in the wrong spot. Sometimes you have to make/modify tools to get the job done.
 
bluerooster said:
We still talkin' Cessna tank covers? IIRC there's several screws that cannot be had from the backside. (along the rear spar comes to mind) and those are usually the ones needing the heads drilled off.
Click to expand...

simply take a 1" cut off disk in a dremel tool and remove the head, remove skin /tank cover, and remove the screw with a pair of vicegrips. then replace all the anchors.

when you put it back on, use nickel antiseze on each screw, and you will not have any troubles with problem again.
 
You must log in or register to reply here.
Back
Top