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Check those AFT Spar bolts

vic syracuse

vic syracuse

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It seems that about 40%-50% of the RVs on which I perform CI's or prebuys have the wrong bolt/nut combination on the aft spar. The aft spar actually has some movement on it during flight loads, and can move. Therefore it requires a drilled bolt, castellated nut, and cotter key. Most of the ones I see have a fiber locking nut on them. Some even have the fiber nut on the drilled bolt!

I'd post a picture but I think it is pretty self-explanatory. Most of the RV's can be checked with a flashlight by crawling underneath and looking past the flap. It is also very easy to remove the last two screws on the wing root fairing and peel it back to inspect.

Vic
 
and if they are not drilled perfectly square put a set of spherical washers on them.
 
Plans

vic syracuse said:
It seems that about 40%-50% of the RVs on which I perform CI's or prebuys have the wrong bolt/nut combination on the aft spar. The aft spar actually has some movement on it during flight loads, and can move. Therefore it requires a drilled bolt, castellated nut, and cotter key. Most of the ones I see have a fiber locking nut on them. Some even have the fiber nut on the drilled bolt!

I'd post a picture but I think it is pretty self-explanatory. Most of the RV's can be checked with a flashlight by crawling underneath and looking past the flap. It is also very easy to remove the last two screws on the wing root fairing and peel it back to inspect.

Vic
Click to expand...

My 7a plans clearly show bolt, washer, nut and cotter pin.
 
wirejock said:
My 7a plans clearly show bolt, washer, nut and cotter pin.
Click to expand...

I think the plans have always had it, but my guess is that a lot of people get to that point in the build, and have gained enough confidence that they stop consulting the plans for a lot of things...I know I caught a few mistakes of my own after going back and looking at the plans that I had earlier just skimmed over.

Chris
 
my guess is that a lot of people get to that point in the build, and have gained enough confidence that they stop consulting the plans for a lot of things
Click to expand...

This may sound like OCD, or maybe it's just a side effect of the rigorous engineering we do at work, but...

Prior to the DAR inspection, I photocopied all of the preview plans, and then went over them and verified that each and every item on every page, including each of the detailed drawing, hardware callouts, etc., had been done IAW the plans (or there was a very good reason for a variance), checking off on paper every item.

If I missed anything, it wasn't for lack of trying to verify every item! :)
 
Thanks

Thanks for the Tip...or Heads Up VIC!
It was a pleasure to meet you in LKU for the RV-7 pre-buy!
I learned things from your visit!
Look forward to seeing you at a fly-in.
 
Electronic drawings show a fiber insert nut, no?

vic syracuse said:
Therefore it requires a drilled bolt, castellated nut, and cotter key. Most of the ones I see have a fiber locking nut on them. Some even have the fiber nut on the drilled bolt!
Vic
Click to expand...

Did this last night. Looking at the electronic drawing file:
Drawing 20, area F-1 shows:
AN3-10A bolt
AN960-10 Washer
AN365-1032

Is not an AN365-1032 have a fiber insert?
 
BenNabors said:
Did this last night. Looking at the electronic drawing file:
Drawing 20, area F-1 shows:
AN3-10A bolt
AN960-10 Washer
AN365-1032

Is not an AN365-1032 have a fiber insert?
Click to expand...

That is just part of the F-705 bulkhead assembly. The discussion is regarding the actual wing rear spar attachment. See Drawing 38, Section H-H, Zone A4.
 
Hey Ben,
Check out #38 section H-H. The bolt that he's referring to is the one that connects the rear spar of the wing to the fuselage.
 
At least on the vintage for my 6, the bag contents for this hardware was an AN365 and A bolt. That is what the factory provided. They didn't provide a drilled bolt. This might explain why so many are this way.
What is in the current kits inventory sheet for this bolt? Do they supply the correct bolt and nut?

I check mine at each CI, and while it makes sense that this bolt can move, mine has always remained torqued. So, each time I get there in my CI, with full intent of changing it out, I check it and move on.
I am not arguing this shouldn't be a drilled and safety'd assembly, but, the factory didn't seem to care at the time.

I think this falls into the category of "good practice", rather than a true safety concern. I have never heard of any issues related to using a nyloc here, but I am not saying it isn't a good idea, and it is what the plans show.
 
And we're not just talking about the -7/7A, right? So, on the -9/9A, on drawing 38 Section G-G, it lists:

AN5-10 Bolt
3x AN960-516 Washer
AN310-5 Nut
MS24665-208 Cotter Pin

These attach the W-907 Rear spar assembly to the F-705 bulkhead assembly.

Cheers,
 
sbal0906 said:
And we're not just talking about the -7/7A, right? So, on the -9/9A, on drawing 38 Section G-G, it lists:

AN5-10 Bolt
3x AN960-516 Washer
AN310-5 Nut
MS24665-208 Cotter Pin

These attach the W-907 Rear spar assembly to the F-705 bulkhead assembly.

Cheers,
Click to expand...

Yes, but what does Van's supply you with? I am curious.
 
JonJay said:
Yes, but what does Van's supply you with? I am curious.
Click to expand...

Are they supplied with the wing kit or the fuselage kit? If it's the wing kit, I'll have to check when I get home. I don't have the fuse kit yet. I did do the inventory for the wing kit so if those parts are listed in the inventory list then I can say they are included.
 
sbal0906 said:
Are they supplied with the wing kit or the fuselage kit? If it's the wing kit, I'll have to check when I get home. I don't have the fuse kit yet. I did do the inventory for the wing kit so if those parts are listed in the inventory list then I can say they are included.
Click to expand...

Thanks, but I am not saying Van's didn't include the parts. Did they include the correct parts?
I do not know what kit they supplied them in. Perhaps someone currently at this stage can comment.
If Van's has continued to supply the "wrong" hardware, or different than the plans, what Vic is seeing would have a common thread.

( typing while someone was answering. Good to know they supplied the correct hardware with that kit - Thanks Raymo! )
 
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Always a drilled bolt for the -6

JonJay said:
At least on the vintage for my 6, the bag contents for this hardware was an AN365 and A bolt. That is what the factory provided. They didn't provide a drilled bolt. This might explain why so many are this way.
What is in the current kits inventory sheet for this bolt? Do they supply the correct bolt and nut?

......
Click to expand...

That may be what they provided, but the -6 plans on sheet 46 have always specified a drilled bolt.

The early plans called for a AN5-7 bolt, AN310-5 nut and a AN960-519 washer.

A later edit in 1997 changed it to a AN5-10 bolt and added the cotter pin.

In 2001 the number of washers call out was increased to 3.

A drilled bolt has always been specified for that location on the -6.
 
az_gila said:
That may be what they provided, but the -6 plans on sheet 46 have always specified a drilled bolt.

The early plans called for a AN5-7 bolt, AN310-5 nut and a AN960-519 washer.

A later edit in 1997 changed it to a AN5-10 bolt and added the cotter pin.

In 2001 the number of washers call out was increased to 3.

A drilled bolt has always been specified for that location on the -6.
Click to expand...

.... I said that Gil. But if they kept supplying the wrong hardware, in the right bag, it makes sense why Vic see's so many of these installed. I have a hard time believing that so many would simply substitute without a reason if the right hardware was in the kit. Assumptions would be made....
It was a long time ago, but I questioned the factory on this. Since it was a long time ago, and said person no longer there, I will just let rest what they told me. It is a simple thing to follow the plans and no reason not too. Thanks to Vic for his post.
Moving on now.....
 
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Bolt orientation

My DAR questioned the orientation of the bolt but I showed him in the plans how Van's had it oriented.
 
JonJay said:
.... I said that Gil. But if they kept supplying the wrong hardware, in the right bag, it makes sense why Vic see's so many of these installed. I have a hard time believing that so many would simply substitute without a reason if the right hardware was in the kit. Assumptions would be made....
It was a long time ago, but I questioned the factory on this. Since it was a long time ago, and said person no longer there, I will just let rest what they told me. It is a simple thing to follow the plans and no reason not too. Thanks to Vic for his post.
Moving on now.....
Click to expand...

The -6 hardware provided was frequently of the wrong length. Even the bolt in question had it's length changed in a revision...:)

I dumped all of my kit hardware in trays and just picked what fit, using the plans to specify the type of hardware. Putting the wrong hardware in without checking the plans is a big boo-boo. :rolleyes:

If original -6 builders simply went by bag labels there will be many bolts too short...:)
 
az_gila said:
The -6 hardware provided was frequently of the wrong length. Even the bolt in question had it's length changed in a revision...:)

I dumped all of my kit hardware in trays and just picked what fit, using the plans to specify the type of hardware. Putting the wrong hardware in without checking the plans is a big boo-boo. :rolleyes:

If original -6 builders simply went by bag labels there will be many bolts too short...:)
Click to expand...

Too long, too short, absolutely agree. Also, substitutions where made in the early days. Some of those substitutions where hardware.

If you found the wrong hardware, and called the factory, and they told you it was fine.... just sayin...., Is that still a big boo-boo? :rolleyes: hmmmm..... maybe.

I love a mystery, and again, there is a reason Vic is finding this a common place that the hardware doesn't match plans and it isn't by chance.
 
JonJay said:
....
I love a mystery, and again, there is a reason Vic is finding this a common place that the hardware doesn't match plans and it isn't by chance.
Click to expand...

Yes, it's a mystery...:)

But I think it's because early -6 builders somewhat gave up on the plans by the time the wings got attached and simply used "standard" hardware without looking at the plans to see if a specific locations called for "special/different" hardware..

Did anyone really check bags of hardware that far along in the build process..:)
 
az_gila said:
Yes, it's a mystery...:)

But I think it's because early -6 builders somewhat gave up on the plans by the time the wings got attached and simply used "standard" hardware without looking at the plans to see if a specific locations called for "special/different" hardware..

Did anyone really check bags of hardware that far along in the build process..:)
Click to expand...

Of course we didn't read the plans. We needed them to start fires in our caves.
 
The bolt specified in the plans for all RV kits is an AN5 with a castellated nut and cotter pin.

AN5 bolts are only used in a few places in an RV. The rear spar attach and the landing gear legs are the only ones I can think of right now so short AN5A bolts would have never been intentionally supplied.

The RV-6A I completed in 1993 was supplied with castellated nuts and drilled AN5 bolts and they were called out in the plans.

All new designs since the RV-6 have specified and supplied the same bolt (I think it is in the finish kit hardware).
 
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rvbuilder2002; said:
....short AN5A bolts would have never been intentionally supplied.
Click to expand...

I believe you Scot, and was hopeful you would chime in.
I am still dumbfounded why so many keep showing up, and I know what was supplied to me.... Others would have to intentionally order the wrong hardware as AN5A's typically aren't just laying around. Why would someone do that?
No matter. If my kit was the only one in the fleet, others are just being careless.

I didn't mean to derail Vic's safety post. It does'nt matter why the wrong hardware is being used.
 
Not a shipment issue

OK, sorry, been busy all day and haven't had time to check this. The bolts are supposed to be drilled and castellated. Just yesterday I removed 2 more from the AFT spar in an RV-8 and they WERE drilled bolts(AN5) but yet had fiber nuts on them. I see many that way.
My guess is that at the airport when final assembly occurs, everyone forgets that it is supposed to be castellated and doesn't check because the plans are left at home.

And I hear you on "they haven't moved so I leave them," but I don't think that is the right approach. My opinion. :)

Vic
 
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vic syracuse said:
And I hear you on "they haven't moved so I leave them," but I don't think that is the right approach. My opinion. :)
Vic
Click to expand...

Your right Vic. Not just an opinion. Good practice is just that.

Again, thanks for posting all the safety items you discover in the many RV's you inspect.
 
az_gila said:
I dumped all of my kit hardware in trays and just picked what fit, using the plans to specify the type of hardware. Putting the wrong hardware in without checking the plans is a big boo-boo. :rolleyes:
Click to expand...
I did the same, and if I couldn't find the hardware specified on the plans, I put in a quick order to ACS. The rear spar/fuselage junction is supposed to allow for a small amount of rotation...so don't torque it down!
 
az_gila said:
Why would he question it? The bolt is in "standard orientation" with the head forward.
Click to expand...

Gil,

That's just it - on the 9/9A plans for DWG 38 Section G-G the bolt head is aft - this may be due to flap clearance. I can't find a revision on Van's site telling me the orientation should be otherwise.
 
Bolts

Getting ready to change mine on my RV6.
Should they be torqued to proper numbers or snug the plans show the correct way to install bolt?Im pretty sure from the torq seal I have in place there is no movement going on .
Bob
 
6 Gun said:
Getting ready to change mine on my RV6.
Should they be torqued to proper numbers or snug the plans show the correct way to install bolt?Im pretty sure from the torq seal I have in place there is no movement going on .
Bob
Click to expand...

Yes. However, with any castellated nut, you have to get lucky that you can get the cotter key in at a precise torque value. You can experiment with combinations of standard and -L washers. Get it close.
I don't know what the plans show, but on the 6 you can easily put the bolt in the proper orientation.

I don't think there is much if any movement at this joint, but per plans is the proper way to do this and kind of a standard for rear spar connections in other airplanes I have seen. Van was an excellent engineer and he would have done it the way he deemed best regardless.
 
Fearless said:
Gil,

That's just it - on the 9/9A plans for DWG 38 Section G-G the bolt head is aft - this may be due to flap clearance. I can't find a revision on Van's site telling me the orientation should be otherwise.
Click to expand...

In AC43.13 where "standard" fastener orientation is addressed, it also adds "unless specified otherwise by the manufacturer". There are numerous instances in RV's where a deviation from the standard is recommended.

Having said that, in this particular case I am not sure why the bolts are specified to be reversed because there would be no interference if the nut was on the aft side. It is possible that it is because of a late design change in the flap leading edge but I don't recall one. So in the case of the RV-9 it would be acceptable to install the bolt in the normal orientation.




Regarding movement of this joint and people seeing no evidence of it.......

It all depends on the loads the wing has experienced!

I assure you that if the wings are loaded to limit load values, there is significant flex/deflection in the wings (witnessed during many different static load tests) which translates to some amount of movement at the aft spar attach point.
 
rvbuilder2002 said:
Regarding movement of this joint and people seeing no evidence of it.......

It all depends on the loads the wing has experienced!

I assure you that if the wings are loaded to limit load values, there is significant flex/deflection in the wings (witnessed during many different static load tests) which translates to some amount of movement at the aft spar attach point.
Click to expand...

Very good point Scott.
This also leads into checking the screws of the overlap of the fuselage bottom skin to the wing. I have found these need to be tightened up a bit over time. I think many do not think to check them.
 
Last edited:
Torque it up a bit more...

JonJay said:
Yes. However, with any castellated nut, you have to get lucky that you can get the cotter key in at a precise torque value. You can experiment with combinations of standard and -L washers. Get it close.
I don't know what the plans show, but on the 6 you can easily put the bolt in the proper orientation.

......
Click to expand...

AC43.13 allows quite a spread of torque allowance to get the cotter pin holes to line up.

While a AN5 bolt is usually listed at 100-140 in lbs, the torque can be increased to the maximum if needed to get the alignment, which is 225 in lbs.

As usual, add the "drag torque" to the above numbers, but this is pretty minimal for a non-locking nut.

f. When installing a castle nut, start
alignment with the cotter pin hole at the minimum
recommended torque plus friction drag
torque.
NOTE: Do not exceed the maximum
torque plus the friction drag. If the
hole and nut castellation do not align,
change washer or nut and try again.
Exceeding the maximum recommended
torque is not recommended.

https://www.faa.gov/documentLibrary/media/Advisory_Circular/Chapter_07.pdf
 
this bolt acts as pin. if you apply torque to the nut to apply a clamp load and the joint moves it will fret and then it will lose the clamp load over time. I snugged mine up hand tight.
 
Tank attachment to the fuse

While on the subject of wing attachment bolts and I hope this is not a drift from the topic, the plan calls for a nut plate for the bolt on the inner tank attachment bracket to the fuse which I never understood why. I used a standard locknut but I wonder why a nut plate since one has full access to both side (bolt and nut)
 
Bolts

So far I learned that the bolts just a pin and some install hand tight .Also some spars move and some don't.Others torque up to a max of 225 in pd to line up cotter key and if its to tight and moves it will gall the metal.
Ok now I know what I need to do.
First I need to grease up joint with high pressure grease to make sure it don't gall.
Then I need to tighten somewhere between hand tight and max.
I can install as called out in plans with nut to the rear unless I have a 9 then put it in backwards.
Or the ones with fiber nuts are working so just leave it alone.
Not picking on anyone and its been a fun read.This is how I do most things anyway.
Bob
 
Bavafa said:
While on the subject of wing attachment bolts and I hope this is not a drift from the topic, the plan calls for a nut plate for the bolt on the inner tank attachment bracket to the fuse which I never understood why. I used a standard locknut but I wonder why a nut plate since one has full access to both side (bolt and nut)
Click to expand...

Did you follow the installation instructions for that fastener? It does not get fully torqued so that the tank brackets can easily separate without rupturing the tank in a wing-shear event such as an off-field landing. A standard lock-nut is not appropriate for this and a drilled-head bolt must be used and safety wired. A nutplate is probably specified because it would be somewhat difficult to install a cotter pint with a castle nut in that location.

Skylor
 
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skylor said:
Did you follow the installation instructions for that fastener? It does not get fully torqued so that the tank brackets can easily separate without rupturing the tank in a wing-shear event such as an off-field landing. A standard lock-nut is not appropriate for this and a drilled-head bolt must be used and safety wired. A nutplate is probably specified because it would be somewhat difficult to install a cotter pint with a castle nut in that location.

Skylor
Click to expand...

I did follow the instructions and mine is not torqued for the very reason that you have mentioned. But still it does not make it any more clear as why a nut plate and not a standard locknut. If there is one bolt/nut that you have full unrestricted access to it, it would be this one ;)
 
Bavafa said:
While on the subject of wing attachment bolts and I hope this is not a drift from the topic, the plan calls for a nut plate for the bolt on the inner tank attachment bracket to the fuse which I never understood why. I used a standard locknut but I wonder why a nut plate since one has full access to both side (bolt and nut)
Click to expand...

Not singling you out because this happens all the time, but deviating from what the plans specify and then admitting that you don't have any idea why the plans say what they do is not a good idea.

A nut plate is used for a very specific reason.

In some crash situations the wing may deflected aft which causes the fuel tank to move outboard away from the fuselage.
The design of the joint is to allow the bracket on the tank to pull away from the support bracket on the fuselage instead of the root rib being pulled out of the tank. The nutplate is used to help minimize the likelihood of the of the fastener being able to tilt sideways and jamb up instead of allowing the clevis on the fuel tank to freely slide out. So it is also important to orient the nutplate laterally as shown in the drawings and to tighten the bolt as described in the plans/manual.
 
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6 Gun said:
So far I learned that the bolts just a pin and some install hand tight .Also some spars move and some don't.Others torque up to a max of 225 in pd to line up cotter key and if its to tight and moves it will gall the metal.
Ok now I know what I need to do.
First I need to grease up joint with high pressure grease to make sure it don't gall.
Then I need to tighten somewhere between hand tight and max.
I can install as called out in plans with nut to the rear unless I have a 9 then put it in backwards.
Or the ones with fiber nuts are working so just leave it alone.
Not picking on anyone and its been a fun read.This is how I do most things anyway.
Bob
Click to expand...

My only comment to this is to refer to my comments in my previous post and then ask "do the plans say only tighten the bolt finger tight"?
 
Bavafa said:
While on the subject of wing attachment bolts and I hope this is not a drift from the topic, the plan calls for a nut plate for the bolt on the inner tank attachment bracket to the fuse which I never understood why. I used a standard locknut but I wonder why a nut plate since one has full access to both side (bolt and nut)
Click to expand...

If you have a flop tube in the tank (mine is in the left), you will likely find that the threaded end of the bolt interferes with the line installation.
 
6 Gun said:
So far I learned that the bolts just a pin and some install hand tight .Also some spars move and some don't.Others torque up to a max of 225 in pd to line up cotter key and if its to tight and moves it will gall the metal.
Ok now I know what I need to do.
First I need to grease up joint with high pressure grease to make sure it don't gall.
Then I need to tighten somewhere between hand tight and max.
I can install as called out in plans with nut to the rear unless I have a 9 then put it in backwards.
Or the ones with fiber nuts are working so just leave it alone.
Not picking on anyone and its been a fun read.This is how I do most things anyway.
Bob
Click to expand...
Funny Bob -
I think I have contributed to this,...
The fact that there is such a wide array of what is done here, and there has never been an incident, accident, or whatever that I am aware of may tell us something...
Still, Scott is our best resource and I follow whatever he tells me, even if I don't readily see the light. Scott was a hangar mate years ago for a short time, and in his day job, well... this is what he does for a living, and he has done it for a long time, and done it well.
So, the things I learned;
The rear spar can move, at least when heavily g loaded. The fact that some, like mine, show no evidence of it, doesn't mean anything.
Follow the plans.

Whenever anyone I respect like Vic posts a safety concern, I listen. But... I also want to know exactly why. Sometimes this keeps a thread going. I am not sure that is bad thing if we can keep away from the misinformation that many, including myself, might be guilty of spreading. However, any discussion about safety can't be bad.
 
6 Gun said:
So far I learned that the bolts just a pin and some install hand tight .Also some spars move and some don't.Others torque up to a max of 225 in pd to line up cotter key and if its to tight and moves it will gall the metal.
Ok now I know what I need to do.
First I need to grease up joint with high pressure grease to make sure it don't gall.
Then I need to tighten somewhere between hand tight and max.
I can install as called out in plans with nut to the rear unless I have a 9 then put it in backwards.
Or the ones with fiber nuts are working so just leave it alone.
Not picking on anyone and its been a fun read.This is how I do most things anyway.
Bob
Click to expand...

make sure the grease does not promote corrosion. I have seen some strange corrosion on steel from special high pressure grease.
 
rvbuilder2002 said:
Not singling you out because this happens all the time, but deviating from what the plans specify and then admitting that you don't have any idea why the plans say what they do is not a good idea.

A nut plate is used for a very specific reason.

In some crash situations the wing may deflected aft which causes the fuel tank to move outboard away from the fuselage.
The design of the joint is to allow the bracket on the tank to pull away from the support bracket on the fuselage instead of the root rib being pulled out of the tank. The nutplate is used to help minimize the likelihood of the of the fastener being able to tilt sideways and jamb up instead of allowing the clevis on the fuel tank to freely slide out. So it is also important to orient the nutplate laterally as shown in the drawings and to tighten the bolt as described in the plans/manual.
Click to expand...

I don?t mind to be singled out if it is done with good intention and constructive criticism.

I had talked to VANS just to make sure my deviation is not of a great concern and they confirmed that as long as it is properly safety wired/cotter pinned. FWIW, my thoughts on the use of a nut plate was due to the fact that since this is not a properly torqued bolt, it has a greater chance of coming loose, hence both the bolt and nut needs to be fixed. I think it is also important to note that the safety wire ought not to go to the slotted bracket, just for the reason you have stated.

On other notes, if my memory serves me right, Vans suggested normal torque value for the aft bolt and not finger tight.
 
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