Paint & Attachment Hardware

During the painting process what happens to all the attachment hardware on the various controls surfaces. For example the nuts and bolts and spacers on the aileron attachment brackets. Is all this hardware fully removed for paint? If so I assume any of the lock nuts need to be replaced and everything has to be retorqued (is that a word??) If so do I set all the hardware as if it were a final install during the build process?

I would appreciate the input.

Thanks,
Steve

Good question Steve. I'm learning that process right now. Basically, every painter will remove the control surfaces so I don't see the point in torquing everything unless you intend to fly before paint. We recently disassembled every control surface so the painter could have access to all surfaces but I don't regret getting everything assembled once before paint so I could align, gap, space, etc everything.

Hope this helps.

ssisca said:

During the painting process what happens to all the attachment hardware on the various controls surfaces. For example the nuts and bolts and spacers on the aileron attachment brackets. Is all this hardware fully removed for paint? If so I assume any of the lock nuts need to be replaced and everything has to be retorqued (is that a word??) If so do I set all the hardware as if it were a final install during the build process?

I would appreciate the input.

Thanks,
Steve

Click to expand...

Yes, hardware has to be removed.
Yes, it must be re-torqued.
Nuts are cheap, but many will re-use a lock nut as long as you cannot turn it by hand. Remember to add the running torque to the published torque table.
Personally I never put on a nut/bolt or a hose or other fitting without torquing to final value. Too many accidents from loose hoses. Exception: if I must leave a hose or nut not tightened to final torque, I hang a large piece of red tape on it, as a reminder.

Thanks guys...I will continue to torque everything down as if were final and just do it again as necessary after paint.

Bob...please clarify what you mean by "Remember to add the running torque to the published torque table" I have been torquing each fastner according to the range in the table provided in the manual. Is there something else I need to be doing?

Thanks,
Steve

Torque

Bob is talking about adding more in-lbs of torque on nuts that have some friction built into them. For example, nylocs have the friction of the nylon insert. Your torque drive will need to overcome this small amount of friction before you are actually measuring the torque of the nut you're tightening. For example, if you have to torque something to 25 in-lbs and the friction of that nyloc takes 3 in-lbs to overcome, you need to tighten the nyloc to 28 in-lbs. Makes sense? I just used the high end of the Vans published torque ranges to account for this.

Ah! David beat me to it.

If it's a plastic insert type lock nut, there's a certain amount of torque required to turn it before it starts clamping. That torque needs to be added to the published torque spec. For instance, let's say you have an AN3 and the torque spec says 20-25 in-lb. If your torque wrench reads 5 in-lb. just turning the nut onto the shaft, then your final torque should be 25-30 in-lb.

Thanks guys...I feel silly not knowing that. I must have missed that somehow in the manual or table. I'll go back and check all my previous torque values. Using the higher end of the torque value sounds like a good plan. I can't imagine a nyloc requiring more than 3-5 in-lbs and if memory serves the range would easily cover that. Great information much appreciated!

Steve

Good plan Steve

Good plan Steve!
After building 2 airplanes I have yet to figure out how people use torque wrenches to attach control surfaces???
A rule of thumb applied to lock nuts is 2 threads showing at the exit end of the nut.
This of course requires the correct length of bolt and washers for the attachment. You can be sure that a new lock nut will not back out if 2 full threads are showing, no matter what the torque. It also provides a visual clue as to the condition of the attachment.
If you do succeed in using a torque wrench by all means use it.

I hope people aren't confused. Having two or more threads showing insures the nylock is engaged and won't back off. Having proper torque insures the bolt has the proper pre-load, to maximize strength while minimizing fatigue. Be careful if not using a torque wrench - it is very easy to over torque an AN3 bolt.

Others have mentioned accounting for the drag on lock nuts. You need to be more careful with all metal lock nuts; some of them have a lot more running drag.