C

Camillo

Well Known Member
Hallo to everybody. I just encountered a big problem.

I'm finishing up my QB wings. I was mounting the aileron bellcrank torquing two of the four AN bolts which attach the aileron bellcrank hinge to the main spar. I set my torque wrench to 110 because bolts arrived at this setting with QB wing kit (I emailed Van's a few months ago complaining of this overtorquing...and they told me to unscrew them and set to the proper torqing values...I just let them there until I needed to assemble the bellcrank I took out bolts and remembered the torquing value). I started torquing and...they begun loose all of a sudden. I think the threading broke. The fact is that I tried unwrenching and they don't come out. I tried with other instruments but...nothing. Now bolts are gone; bolt heads are nearly ruined.

I'm also worried about the platenut threading: if it is unthreaded, too, how would I replace them, since they are UNDER the main spar? Any suggestions?

I hope I was clear. I'm italian and my technical english is bad...

Thank-you.
 
Yikes. Way over torqued indeed. It does sound like the platenuts are stripped and should be replaced. Us slow build people reached in there to buck the rivets that hold the nose ribs on the main spar. You should be able to get in there to rivet new platenuts.
 
Aww nuts!

Is there a hole in the spar that you can reach through? I thought it was solid??

Anyway if its just the bolt that is stripped (one can hope) take a pair of wire cutters and grip under the bolt head...In other words use the wire cutter blade to put tension on the bolt.

At the same time use a socket wrench to unscrew the bolt...You might get lucky and the remaining thread will re-engage and allow you to unscrew the bolt.

Then try inserting a new bolt and torquing up very gently.

Frank 7a
 
To scard:

No, main spar does not have any hole for rivets. Platenuts are attached to the tie down bar and tiw down bar is attached to spar with bolts. I think I can take out tie down bar simply unscrewing the four bolts, but...I'm not sure that I would be able to mount it again, without enough space to reach that place.

To frankh:

Yes, I hope that bolt is stripped and not platenut. I already tried in your way with a screwdriver and the torque wrench. I will try again with a narrower blade which fits between bolt head and washer.

I regret Van's didn't tell me to careful tighten bolts not more than 50 pound/inch. I thaught manual settings would only a suggestion and that philippines specialist knew their job. Now I know that they overtightened bolts and I...made the same error.
 
Alright, I'm looking at the plans now. My opinion is that the nutplate should be replaced if this assembly has been over torqued so much as to have stripped anything. If you really have to get a hand in there to get the tie-down bar off or back on, you can remove the tank and reach in there. Otherwise, I would think that you could rig up some kind of arm extension with a wad of duck tape on the end or something to reach in from the wing tip end to the fourth leading edge bay with the tie down bar in it for retrieval after all the bolts are out, or positioning upon reassembly. Then, capture the tie down bar with the tie down bolt hole through the bottom skin for stability while reinstalling the bolts that hold it on.
 
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Stripped Bolt

Camillo,

Don't worry about removing the bolt with the torque wrench right now. Just use a regular wrench or socket/ratchet combo to remove it. With a pair of diagonal cutters under what is left of the bolt head turn the bolt to remove it. Once removed use a new longer bolt the same size as the removed one to check the threads on the nutplate. If the nutplate is stripped the new bolt should not start or engage the threads at all.
 
I would defenitely remove the tank, and check all of the material back there. Easy to get to with he tank off, at least on my antique slow build.
 
Even if the platenut threads are damaged

as long as the bolt torques up without stripping then there is no reason to remove the nut plate.

Basicalliy if the thread is torqued it will not see any additional tension in service...It just a question of did the bolt strip, the platenut or both.

The diagonal cutters (or wire cutters) under the head are much better than just a screwdriver because you can get way more tension on the bolt to start what is left of the threads than you can with just a screwdriver.

If your wintip is removed I bet you can get your tie down in and out with less work than if you removed the tank.

Try this.....Remove all but one of the bolts.....Pass a long piece of electrical wire through one of the top bolt holes from underneath.

pass a whole bunch of wire through into the nose...Reach in from the wing tip with a long stick/hook to grab the other end of the wire

Do the same again through the other top bolt hole.

Have a helper pull the wires taught from the wing tip, now use you hook stick to guide the plate along the length of wires.

To replace...Tie a knot in the middle of each wire that will prevent the knot going through the plate nuts...now pull the wire from underneath and I bet eventually the tie down plate will end up back here it came from.

Worth a try!..:)

Frank
 
Thank-you to everybody. To Frankh: your technique looks good, but...how would I reinsert four AN bolts which attach tie down to mai spar, since their heads are below the main spar? Tie down has eight bolts: four (heads down) for attaching it to the spar and four (heads up; the ones ruined) for attaching aileron hinges to the spar.

I think that disassembling tank would be better (quicker?).

However, first of all I will remove bolts and check for platenuts threads integrity. Maybe they are all right (but I know Murphy's rule...).

Bye.
 
tank off

Pull the tank and install new nutplates and get it over with as soon as
you can do it safe and clean, otherwise you will always wonder about the
threads.. its not worth it.. fix it and move on.. don't torq anything till
you get the torq list for each bolt size and application.. store the tail and wings and get going on the fuse.. if your not sure about the proper
inch pounds then ask on here , I have done this many times and these
guys are awesome helping with that stuff.. just my take on it..
I don't want to worry about these things everytime I am flying along
having a great time..


Danny..
 
No way taking these bolts off. They are so linked to the washer that there is no space to make grip.
I think that is the bolt threading to be stripped and the remaining threads make grip under the nutplate. Otherwise, if it was the nutplate's thread, bolts would came out easily.
I would like to avoid drilling them.
 
Hmmm

Sounds like the tank is coming off in any case.

So how about take the tank off and using a small rotary disc (like the ones van's sells for cutting the canopy) to cut through the threads about halfway up the nut plate.

So when you have cut through the bolt you will have about half the depth of the nutplate left.

This will avoid you getting too close to the spar and should release the bolt which should then unscrew.

Frank 7a
 
Solved!

Hello.

I solved the problem. I took-off left fuel tank. I drilled out bolt heads. Then I unscrewed the four nuts which join tie down bar with main spar. I removed the tie down bar. I removed the two platenuts (with the remaining ?art of bolts inside) and reinstalled.

The best thing, as usual, is to sit down and think!

Thanks to all.
Camillo
 
godspeed said:
Pull the tank and install new nutplates and get it over with as soon as
you can do it safe and clean, otherwise you will always wonder about the
threads.. its not worth it.. fix it and move on.. don't torq anything till
you get the torq list for each bolt size and application.. store the tail and wings and get going on the fuse.. if your not sure about the proper
inch pounds then ask on here , I have done this many times and these
guys are awesome helping with that stuff.. just my take on it..
I don't want to worry about these things everytime I am flying along
having a great time..
Danny..
Click to expand...

Danny is right. Whip off the tanks and get on with the job of replacing the nutplates. If the threads on the bolts have failed you will have structural damage to the threads on the nutplates at the microscopic level as well. Replace them.

QB builders are reluctant to take the tanks off...but it is no big deal. In fact after you've done it you'll know more about your wing construction and you'll feel much better for it.
 
Nutplate ruined

I'd take a handful of spare nutplates, mount them on a scrap plate of aluminum and punish them exactly like you goofed this one. If they're ruined, you'll be sure you have to face the music and replace the problem nutplate.
 
Yes, maybe I was not enough clear.

I replaced the two "damaged" nutplates and installed new ones. Now my tie-down bar is OK.

The strange thing is that QB wings bolts and nuts torquing values were all wrong! For instance:
- aileron hinges bolts to tie down bar were @110 inch./lbs. (and when I tried to reassemble them at that torque value they broke);
- fuel tank bolts to main spar were all@50 inch./lbs..

They're all AN3 bolts. So correct torquing should be 20/25 inch./lbs. They were all overtorqued. So, now I don't know exactly if I did right re-torquing them @ 25 inch. pound...
 
Camillo said:
Yes, maybe I was not enough clear.

I replaced the two "damaged" nutplates and installed new ones. Now my tie-down bar is OK.

The strange thing is that QB wings bolts and nuts torquing values were all wrong! For instance:
- aileron hinges bolts to tie down bar were @110 inch./lbs. (and when I tried to reassemble them at that torque value they broke);
- fuel tank bolts to main spar were all@50 inch./lbs..

They're all AN3 bolts. So correct torquing should be 20/25 inch./lbs. They were all overtorqued. So, now I don't know exactly if I did right re-torquing them @ 25 inch. pound...
Click to expand...

Camillo, how do you know what the original torque settings were? By putting a torque wrench on them and reading the value while trying to loosen them? Or by trying to tighten them additionally, and reading the torque when the bolts started to turn again?
Torque has to be measured while the fastener is moving in relation to the part or nut it is being fastened to. To re-check torque, you must loosen the fastener, and then torque again to the correct value. You can't determine the original torque value by what it takes to break loose a fastener. Did you ever have trouble removing lug nuts while trying to change a tire on your car? You can bet that they weren't put on with as much torque as what was required to remove them.
 
Yes, you caught my method!
I first tried with low setting, trying to tighten bolt. If I could hear torque wrench "click" prior to see or feel bolt moving, I upgraded torque setting. And so on, until I found the proper setting, which first made bolt move and immediately after hear the "click".
I thaught this was a correct method. Isn't it?
 
No, it's not! You can only re-torque by loosening the fastener, then torque to value. Make sure that the bolt is still rotating when it reaches the required torque. In other words, this is done smoothly, but quickly. once the fastener stops rotating, the "break-loose" torque required to get it turning again can easily exceed the torque value you want.
 
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