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Check those AFT Spar bolts
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 |
Just to clarify, you're talking about the bolt connecting the spar to the fuselage "fork"?
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Vic |
and if they are not drilled perfectly square put a set of spherical washers on them.
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Nuts
Mine has fiber nuts with torque seal no movement.Will watch.
Bob |
Plans
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Chris |
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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! :) |
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Why wouldn't you replace it with the correct combination? Takes about 10 minutes per side. Vic |
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?
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Drawing 20, area F-1 shows: AN3-10A bolt AN960-10 Washer AN365-1032 Is not an AN365-1032 have a fiber insert? |
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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, |
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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! ) |
Always a drilled bolt for the -6
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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. |
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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..... |
Bolt orientation
My DAR questioned the orientation of the bolt but I showed him in the plans how Van's had it oriented.
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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...:) |
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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. |
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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..:) |
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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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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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Again, thanks for posting all the safety items you discover in the many RV's you inspect. |
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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 |
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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. |
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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. |
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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. |
Torque it up a bit more...
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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/...Chapter_07.pdf |
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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.
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