Hardware Check Reminder

[DBeaulieu]

For those eager (including me) builders of quickbuild wings heed the advice regarding checking hardware associated with the wings as received. First wing was gone over and all I needed to do was swap out a few washers under a couple of nuts to get better thread count (none of the flap or aileron brackets fasteners were altered) Just started the second wing yesterday and discovered unseated bolt and completely missing bolt on the false spar aft of the fuel tank cavity. Minor inconvenience but pay attention! Did I mention I love the quickbuilt kit...nutplates not so much?

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[spinningwrench]

Also recommend checking strut attach hardware for correct torque. My AN3 bolts were torqued to 70 in-lbs which is probably close to their failure point. I replaced all the hardware on the strut attach fittings for piece of mind.

[Nev]

My AN3 bolts were torqued to 70 in-lbs which is probably close to their failure point

To clarify, are these the bolts inside the wing ? I'll have to check the plans for mine (4B) but I seem to recall they are AN4. I wonder if yours were torqued to the AN4 recommended torque..

[spinningwrench]

Yes these are the interior bolts on the strut straps bolted to the front spar. There are four AN3's and one AN4 on the Patrol. Your explanation makes sense,

[TJ_Slice]

Instead of creating a new thread, I decided to add to this old one, because it is similar.

I have gotten to the point where I am now installing the aileron cable pulleys. I haven't yet checked any of the wing bolts for torque.

I am curious if people have just dedicated time to check them all at once, or have you been doing them as you go along and are working in the area they are located?


Then we get to actually checking the torque. I have read up on it, but it seems like it would require a digital torque wrench. Am I missing something?

[jaredyates]

I prefer a micrometer click-type of torque wrench. I keep a quarter inch that handles up to 150 inch pounds and a 3/8 that handles up to 200 foot pounds, though I think the most we use on the plane is probably 100 or so. I suppose a digital one may be an option too, in any case consider calibration if it hasn't been done recently.

[TJ_Slice]

I prefer a micrometer click-type of torque wrench. I keep a quarter inch that handles up to 150 inch pounds and a 3/8 that handles up to 200 foot pounds, though I think the most we use on the plane is probably 100 or so. I suppose a digital one may be an option too, in any case consider calibration if it hasn't been done recently.

I have them, but exactly how do you check the torque of an already tightened fastener? Is it a matter of incrementally increasing the torque setting until you get movement?

[Viking]

The safe way to verify torque on fasteners is to loosen them and then re-torque. The torque required to break the friction of an assembled fastener is greater than the “running torque” applied when the fastener is already turning if that makes sense. So loosening the fasteners with a torque wrench won’t give a terribly accurate indication of what you’re dealing with, and once the fastener has been loosened, it needs to be re torqued anyway, so it’s easiest just to back them down a bit and retorque them. If you have serious concerns about over torque, to the point of the bolts being damaged, best to just replace them.

[TLyon]

Instead of creating a new thread, I decided to add to this old one, because it is similar.

I have gotten to the point where I am now installing the aileron cable pulleys. I haven't yet checked any of the wing bolts for torque.

I am curious if people have just dedicated time to check them all at once, or have you been doing them as you go along and are working in the area they are located?


Then we get to actually checking the torque. I have read up on it, but it seems like it would require a digital torque wrench. Am I missing something?

Tube of paint makes it easy to keep track. https://www.aircraftspruce.com/catal...09-25810-1.php

I went through them all over a coupe work sessions. On the first wing, -4s were about right, enough of the -3s were tighter than I was comfortable that I decided to swap them out.
Just for kicks I broke a few off to see what they went to. I didn't write the numbers down, but I think it was around 100+/-5 in-lbs for a -3. Probably would have been fine, but it's one less thing.

My plane won't be perfect, but I figure I might as well control/improve the cheap easy things that I can control. It's been an interesting learning experience to sort through all the opinions on "right" as it relates to airplane construction.

The quote "You'll be fine" that's the builder painted on the canopy rail of my RV has a whole new meaning now. ;-)

[TJ_Slice]

Thanks, I have the torque seal in hand. I'm still wondering what the best way to measure the torque is. I'm thinking of just incrementally increasing the torque setting on my wrench while trying to loosen the fastener until I get some movement, and then just re-torque them.

[jaredyates]

If you aren't concerned about possible permanent damage to the fasteners due to over-torquing, I would just loosen one and then use your torque wrench to tighten it. If you're concerned that it might have been tightened so much that it is damaged, replace it with new hardware and then torque that.