Broken bolt aileron bellcrank attach

So I just made a big mess. I picked the wrong bolt to try out my torque wrench on, the wrench didn't work (set to 20 inch-pounds and it never kicked out) and I over-stressed and sheared the bolt. This is one of the bolts attaching the aileron bellcrank bracket to the spar. So the question is, now what?

I've seen a few people report the same problem and the response is one of 2 things, either try to get the bolt out (drilling and using an easy-out), or replace the platenut. There seems to be some thought that once a bolt has been over-stressed in a platenut, that platenut is not usable any more. If that's the case, then I have to replace it. Of course the platenut isn't easily accessible as the leading edge skins are done.

I've removed the fuel tank (that wasn't any fun) to try to get closer, I'm still a long skinny arm's length away. I suppose I could find someone with skinny arms and remove the tie down bar and then replace the platenut that way. Sure isn't going to be easy. Anyone have any wisdom they could share on how to tackle this?

Broke off an AN3 bolt.... wow, you must have been eating your wheaties. I think you should drill out the affected platenut with the broken bolt and replace it. Use an extension magnet to retrieve the drilled out platenut/bolt. If you can get in behind the platenut area well enough to just hold the new replacement in place while you clecoe it in place from the other side, you're good to go. You might even be able to use the extension magnet to fish the new platenut in close enough to clecoe it in place. When you get the new platenut clamped in place, use 3/32 flush pop rivets to attach it and your done. The rivets are only there to keep the platenut from turning while you torque the bolt, so pop rivets its will work here.

My torque wrench 'click' is pretty vague at the light torque value for an AN3 bolt/nut (20-25), so it's not easy to feel this, especially if the wrench is a long one. Doesn't seem like much, but it's enough.

Good luck!

I have had two torque wrenches fail, one suddenly began to break over at much lower than set torque, the other suddenly would not break over at any torque. You may have simply missed it--20 inch-pounds is a very small amount of force. You need to add 5-7 inch-pounds to the desired torque to overcome the drag from the nyloc nut.
I would try drilling the bolt carefully and trying the easy out. If that works, put another bolt in and tighten.
I think Van's designed several things requiring long and skinny arms. Bet someone at Van's would have suggestions on how to remove and replace that tiedown bar.

Bolt

My skinny little arms will go through the outboard lightening hole in the spar web, but this probably doesn't help you.

I don't think you are correct that the platenut is damaged by shearing off the bolt shank. But to prove it to yourself, do a test piece.

Rivet a platenut to a piece of scrap aluminum, put it in a vice, put in a bolt (through a couple of thicknesses of aluminum to simulate the spar web and aileron bracket) and tighten it until it breaks. Then remove the broken bolt shank (you should be able to get some vice grips on the exposed threads and screw it all the way through the platenut. Now inspect the platenut threads. If they look OK, then I would try drilling the bolt shank in the wing spar and use an easy out to remove. Inspect from both sides (with a mirror or your smartphone inside the leading edge). A female thread is generally stronger than a male thread because the shear diameter is larger.

If you cannot get the broken bolt shank out of the wing spar platenut, then just drill the rivets out and replace the platenut, securing it in place with some blind rivets.

Platenut

I'm in Scott's camp. Drill the plate nut with the bolt in place. Position a rare earth magnet on something so when it comes off, it won't fall. Run a string through the hole. Attach the new platenut to the end of the string with a washer or something on the end of the string. Pull the string so the platenut comes up to the bolt hole. Put a cleko in one rivet hole. Put a bolt in to hold it centered. Rivet as Scott mentions with pop rivets.
Check the torque wrench every time to make sure it clicks. 20 in/lbs is nothing. Just a bit more than finger tight.

Don't feel too bad. I broke a head bolt once. The last one of ten at 75 ft/lbs. Digging that out was not fun. Learned a valuable lesson on hydraulic locking that day. Can't compress oil.

I follow what you are suggesting (drill out the platenut and replace it). Problem with that is that there is nothing to drill out. The platenut is attached to the tie-down bar, not the spar. There are no rivets on the aft side of the spar there at all.

I think my skinny armed son can reach the tie down bar. I'll get him to bring a magnet back to catch the nuts and washers as they come off when I remove the bolts.

So on a slightly related note, how do you guys deal with removing and installing the tank attach bolts - the ones you have to go through lightening holes to get to. There isn't enough room to swing a ratchet in there. I've got an air ratchet that I was able to use with difficulty, but I don't want to use that to reattach because for some reason I don't want to over torque any more bolts.

Stubby

I remember now. Sounds like you have a plan to remove the tie down bracket.
Do you have a 1/4" stubby ratchet? That's what I used. I practiced in case the tanks had to be removed.
Getting a 1/4 torque wrench in there is a challenge but I remember doing it when I installed the tanks just to be sure I could do it if they ever came off again.

My skinny armed kid may regret it, but we managed to extract the tie down bar, replace the platenut and re-install. It wasn't all that bad (for me). I picked up a 1/4" stubby ratchet and that worked great, both for holding the nut in place on the tie-down bar and for re-securing the fuel tank. All told, cost me about 5 hours and a tiny order to Van's for some AN3-5A bolts. It may cost me a new torque wrench too since this one doesn't work (I tried torquing a bolt before it was even finger tight and it never tripped).

I always recommend that people try out a new torque wrench with a scrap bolt clamped in a bench vise.
A lot of people are accustomed to hearing a click on the break style torque wrenches. Usually the first click you hear ( if you are only listening for an audible indication), is the sound made when the bolt snaps at about 75 inch pounds.
Yours may have a problem.... But before you give up on it, try testing on a junk AN3 bolt, and see if you can feel the indicator.... It can be hard to detect until you know what it feels like.

Torque wrench

rvbuilder2002 said:

I always recommend that people try out a new torque wrench with a scrap bolt clamped in a bench vise.
A lot of people are accustomed to hearing a click on the break style torque wrenches. Usually the first click you hear ( if you are only listening for an audible indication), is the sound made when the bolt snaps at about 75 inch pounds.
Yours may have a problem.... But before you give up on it, try testing on a junk AN3 bolt, and see if you can feel the indicator.... It can be hard to detect until you know what it feels like.

Click to expand...

I liked this one so much I bought the 3/8" as well. The click is pretty subtle at 20 in/lbs but I got used to it.
http://www.amazon.com/CDI-1501MRMH-4-Inch-150-Pound-Capacity/dp/B000KL4HZ8

Flying Canuck said:

So I just made a big mess. I picked the wrong bolt to try out my torque wrench on, the wrench didn't work (set to 20 inch-pounds and it never kicked out) and I over-stressed and sheared the bolt.

Click to expand...

You say 20 in lbs, you are aware you need to add in the drag torque created by the fastner your bolt is going into? For example, AN3 bolt 20-25 in lbs of torque. Nylock bolt needs 5 in lbs of torque for the bolt to turn through the nut, equals 25-30 in lbs on the torque wrench.

Park Tools

I use this wrench for low torque settings. I really like it

So my torque wrench works fine. Nothing a little user training couldn't fix. Thanks rvbuilder2002 for the suggestion for testing the wrench. I felt and saw what it was doing when it tripped at 40 or so when I tried it on a bolt in my vise. There's really nothing to hear. 20 inch-pounds is really subtle.

Thanks for all the help on this one. Off to the next challenge now.