Washer Stackup on Rear Spar Bolt

s24789 · #1 09-25-2011, 05:26 AM

Hope someone can help. I have not called Van's about this yet. Ready to install the real (final) rear wing spar bolts on our 7A. The plans show three washers on the nut side of the spar (forward) but none on the bolt head side (rear). This seems a little strange that in this highly loaded area that a washer under the head is not used to keep the bolt head from digging into the wing spar. Thoughts ?
Thanks
phelps

RV6AussieNick · #2 09-25-2011, 08:19 AM

Hi Kevin,

For most airframe applications the max number of washers is 1 under the head and 2 under the nut, maybe VAN's can explain why the drawing shows 3 under the nut, I'd be interested to know why it's drawn that way.

Cheers,

ArVeeNiner · #3 10-19-2011, 11:45 AM

Any word on this? The 9 also shows 3 washers under the nut and zero under the head.

Also, the head of the bolt is show pointed aft on the 9 drawing and forward on the 7. It probably doesn't make a difference but you have to wonder why it's different.

az_gila · #4 10-19-2011, 12:07 PM

Quote:

Originally Posted by s24789

Hope someone can help. I have not called Van's about this yet. Ready to install the real (final) rear wing spar bolts on our 7A. The plans show three washers on the nut side of the spar (forward) but none on the bolt head side (rear). This seems a little strange that in this highly loaded area that a washer under the head is not used to keep the bolt head from digging into the wing spar. Thoughts ?
Thanks
phelps

It's highly loaded but the bolt is really acting as a hinge and not as a clamp...

ArVeeNiner · #5 10-19-2011, 05:00 PM

I just talked to Van's. They said you can put one of the three under the head if you want. I like this much better.

alpinelakespilot2000 · #6 10-19-2011, 05:27 PM

Quote:

Originally Posted by ArVeeNiner

Any word on this? The 9 also shows 3 washers under the nut and zero under the head.

Also, the head of the bolt is show pointed aft on the 9 drawing and forward on the 7. It probably doesn't make a difference but you have to wonder why it's different.

Which drawing shows these Kelly? The drawing I see (DWG 38) shows 3 washers but doesn't specify under head or washer. Also, it shows the nut on the aft side which makes sense since (a) that's the only side from which you can torque it and (b) that's the only way you can inspect the cotter pin on preflight, unless you take the wing root fairings off. FWIW, my rears spar bolts have one head under the washer, 2 under the nut.

s24789 · #7 10-19-2011, 05:48 PM

You will end up playing a game with washers to get the nut to line up for the cotter key.
Phelps

ArVeeNiner · #8 10-19-2011, 07:44 PM

Quote:

Originally Posted by alpinelakespilot2000

Which drawing shows these Kelly? The drawing I see (DWG 38) shows 3 washers but doesn't specify under head or washer. Also, it shows the nut on the aft side which makes sense since (a) that's the only side from which you can torque it and (b) that's the only way you can inspect the cotter pin on preflight, unless you take the wing root fairings off. FWIW, my rears spar bolts have one head under the washer, 2 under the nut.

Yes, drawing 38, zone C3. You can see the nut facing forward (180 degrees from what is called out on the RV-7 drawing) and all the washers stacked under the nut. I may have a later rev of the drawing at the hangar which I'm going to in a few minutes so I'll double check.

alpinelakespilot2000 · #9 10-19-2011, 08:07 PM

Quote:

Originally Posted by ArVeeNiner

Yes, drawing 38, zone C3. You can see the nut facing forward (180 degrees from what is called out on the RV-7 drawing) and all the washers stacked under the nut. I may have a later rev of the drawing at the hangar which I'm going to in a few minutes so I'll double check.

Yeah, I have the same drawing, Kelly. Hadn't noticed that little part in C3. Good catch.

However, if you look at the G-G blowup, you'll notice they're showing you the left side which means you're viewing it from the rear. Castle nut and cotter pin clearly shown, not the bolt head. Thus, it appears that the "Wing attach top view" and the "Section G-G" contradict each other. Am I reading that right?

Unless Van's does really mean for the bolt head to be aft, I would think common practice and, more importantly, ability to inspect the cotter pin, would dictate the nut being on the aft side of the spar. Did you happen to talk to Van's about this issue?

ArVeeNiner · #10 10-19-2011, 09:17 PM

Quote:

Originally Posted by alpinelakespilot2000

Yeah, I have the same drawing, Kelly. Hadn't noticed that little part in C3. Good catch.

However, if you look at the G-G blowup, you'll notice they're showing you the left side which means you're viewing it from the rear. Castle nut and cotter pin clear shown, not the bolt head. Thus, it appears that the "Wing attach top view" and the "Section G-G" contradict each other. Am I reading that right?

Unless Van's does really mean for the bolt head to be aft, I would think common practice and, more importantly, ability to inspect the cotter pin, would dictate the nut being on the aft side of the spar. Did you happen to talk to Van's about this issue?

You know, I forgot to ask them. I caught it today when I compared my 9 drawings to my friend's 7 drawings. Strength wise, it makes no difference but you make a good point about checking the nut side during inspections. That is how I will install it.