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Wing bolt intent (9A)

rjcthree

Well Known Member
I'm struggling with the lubing of the wing bolts prior to installation. As I see it, if the bolts are lubed in any way, there is no way that the lube won't find it's way between the spar faces, resulting in less friction at a given clamp load, as provided by the torqued bolts. It's likely this would get LESS over time (at least in the short term) with wicking. This leaves the attachment of the wing to center section tied to the shear of the bolts 'alone'. Not sure I'm good with the crude math I've done on that (BSME/PE), which admittedly was done on the 7/16" bolts alone.

Or am I overthinking this? Rick 90432 (hoping to test mount wings this weekend)
 
I'm struggling with the lubing of the wing bolts prior to installation. As I see it, if the bolts are lubed in any way, there is no way that the lube won't find it's way between the spar faces, resulting in less friction at a given clamp load, as provided by the torqued bolts. It's likely this would get LESS over time (at least in the short term) with wicking. This leaves the attachment of the wing to center section tied to the shear of the bolts 'alone'. Not sure I'm good with the crude math I've done on that (BSME/PE), which admittedly was done on the 7/16" bolts alone.

Or am I overthinking this? Rick 90432 (hoping to test mount wings this weekend)

Yes you are. Don't soak them.
 
Yes, you're overanalyzing (not overthinking - thinking is good).

3 for 3, bolt it on per plans and continue.

greg
 
Wing Bolt Lube

I suppose if you use LPS 3, it won't migrate as much since it is more viscous and it seems to harden or polymerize in time. It is designed for anti-corrosion applications. Some people use a wax like Boelube.
Leland
 
What every amount of strength that is gained from clamping pressure is miniscule compared to the shear strength available from the bolts... lubing to prevent damage during installation is far more important than any amount of reduction in clamping friction.
 
Above post has it right, bolts carry the load. But do clean all lube off the theads before you torque the nuts.
 
Rememebr that the RV-1 didn't have bolts holding the wings on - it just used taper pins. As others have said - the strength is all in the shear.
 
Just finished putting my wings on a few weeks back. I wiped the bolts clean, then just put a small dab of lube starting about half way back on the bolt.

The issue is how to get the nuts on the bottom bolts. I found out the hard way.

#1 - Start by putting in all 4 bolts so they are inserted through the spar, but not sticking out on the other end.

#2 - The outer most bolt, closet to the wing skin is tapped out to reveal about three threads on the bolt.

#3 - Do some upside down back bending, twisting and yogo to start the nut on the outside bolt. Tighten to firm

#4 - Follow the steps above moving one bolt at a time toward the interior of the plane.

#5 - Torque all from the bolt heads. Next to impossible to get the ft pound torque wrench on the nuts of the bottom row
 
On the -10 my close tolerance wing bolts were very hard to turn. If you must torque the bolt head make sure you measure the turning resistance (torque) and add it to the needed torque on the bolt. Otherwise they may be woefully under torqued.
 
With all-metal locknuts, a little lube on the threads won't hurt, and may even be good in some joints.

For maximum clamp-load for a given torque, you want lube on the threads and under the head and/or nut (whichever you plan to turn). If the clamp load is as high as it should be, the nut backing off is NOT going to be an issue, because of the extreme amount of friction under the head.

This isn't necessarily useful for these wing bolts, since it's an interference-fit shear joint and clamp load isn't really critical (like it would be in a tension or lose-fit shear joint).
 
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