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-   -   RV-6 Wing Screws (https://vansairforce.net/community/showthread.php?t=97924)

Scott Hersha 03-27-2013 08:58 PM

The screws that are missing are #8 screws. There should be #8 plate nuts in the inboard edge of the lower inboard wing skin to accept the screws attaching the belly skin. You could just install the screws if the plate nuts are there. The question is, what structural loads have been imposed by the lack of these screws? If the plate nuts are not there, something important was missed by the builder. Maybe you should keep looking. BTW - good job noticing this omission and investigating it.

Snowflake 03-27-2013 09:00 PM

Quote:

Originally Posted by ChiefPilot (Post 756823)
No, underneath it stops just aft of the tanks.

Now that you mention it, I should know that because that's where I have trouble keeping the free end of the rubber filler strip in place... I remember it's right beside the fuel drain.

I can't remember ever seeing screws under there on mine, either, but i'll definitely be checking it the next time i'm at the airport...

az_gila 03-27-2013 09:04 PM

The joint (overlap) should be bolted per the previous link. http://www.vansairforce.com/communit...99&postcount=7

You might be able to use dome head #8 screws and self locking nuts installed from the top if you remove the upper wing/fus. fairing strip.

If this is possible, you might be able to drill the holes and insert nuts/bolts without taking the wings off.

Check with Vans to see if this is acceptable - it probably is.

fehdxl 03-27-2013 09:11 PM

Quote:

Originally Posted by az_gila (Post 756828)
You might be able to use dome head #8 screws and self locking nuts installed from the top if you remove the upper wing/fus. fairing strip.

Gil,

What's the shear strength of a dimpled screw joint versus just a hole with a dome head screw and nut? My gut says the dimpled is stronger, which is what is called for by Van's in the plans. Sure, anything is better than nothing, but if one wants the full 6 positive G capability...

I suppose some sort of dimple extension/riveter apparatus could be fabricated to make dimples without removing the wing...sounds tough though.

Fly safe,

-Jim

JonJay 03-27-2013 09:13 PM

Quote:

Originally Posted by az_gila (Post 756828)
The joint (overlap) should be bolted per the previous link. http://www.vansairforce.com/communit...99&postcount=7

You might be able to use dome head #8 screws and self locking nuts installed from the top if you remove the upper wing/fus. fairing strip.

If this is possible, you might be able to drill the holes and insert nuts/bolts without taking the wings off.

Check with Vans to see if this is acceptable - it probably is.

I am sure it would be Gil but that opening is tigheeeet. Unless you have eyes on your forehead or are really good with a mirror it would be tough at best.

roee 03-27-2013 09:29 PM

Quote:

Originally Posted by JonJay (Post 756800)
It is not a service or airframe issue, it is a construction issue. Who knows what impact it may or may not have on the strength of the wing.

...
Quote:

Originally Posted by JonJay (Post 756800)
I would be more concerned with what else the builder felt was "unnecessary".

Exactly. This kind of omission in construction makes the entire airplane suspect. And if the builder was trying to brush off this issue with nonsensical talk about service bulletins (a red herring), that again makes the airplane and the builder even more highly suspect.

FitzRX7 03-27-2013 09:44 PM

Well, this wasn't the builder that mentioned the bulletin thing. The guy who's name is on the aircraft as the builder actually passed away 10ish years ago.

It seems like I've got the right idea then, that these are completely necessary for the plane to perform as advertised. Hopefully it gets fixed soon.

Thanks for everyone's inputs, I really appreciate it.

One last thing, how easy would it be to get the FAA examiner person to sign off an aircraft as airworthy with a problem like this? Why wasn't it caught at whatever kind of inspection gets done for that? Please excuse my ignorance on this, hopefully one day I'll build a plane!

roee 03-27-2013 10:34 PM

Quote:

Originally Posted by FitzRX7 (Post 756842)
One last thing, how easy would it be to get the FAA examiner person to sign off an aircraft as airworthy with a problem like this? Why wasn't it caught at whatever kind of inspection gets done for that? Please excuse my ignorance on this, hopefully one day I'll build a plane!

Good question. Easy, depending on who did the inspection. A good DAR who is familiar with RV's and did a thorough technical inspection would have caught this problem. If, on the other hand, the inspection was done by a FSDO guy without any real familiarity with RV's, then something like this could easily slip through the cracks. The legalities of the airworthiness inspection are mostly bureaucratic. It is up to the builder to make sure the airplane is actually airworthy, and that includes choosing the right DAR to do a thorough and meaningful inspection. Not everyone does.

So if you're still interested in buying this airplane, you should seriously consider having it inspected from head to toe by a qualified person familiar with the type. Not for legalities, since it has already been deemed legally airworthy, but for your own peace of mind, to know what if any other major deficiencies in construction may be lurking in there. With something as blatant as what you've found, there's bound to be more.

az_gila 03-27-2013 11:39 PM

Quote:

Originally Posted by fehdxl (Post 756831)
Gil,

What's the shear strength of a dimpled screw joint versus just a hole with a dome head screw and nut? My gut says the dimpled is stronger, which is what is called for by Van's in the plans. Sure, anything is better than nothing, but if one wants the full 6 positive G capability...

I suppose some sort of dimple extension/riveter apparatus could be fabricated to make dimples without removing the wing...sounds tough though.

Fly safe,

-Jim

Yes... the dimpled joint would definitely be stronger in shear.

Thats exactly why I said to check with Vans first...:)

It would be difficult to get fingers, tweezers, swivel sockets extra down in the narrow gap as JonJay says... but if you can get in there, it will be less work than wing removal on a -6, and even less if it's a -6A.

Mel 03-28-2013 07:00 AM

I have to go along with everything said to this point.
I would not consider buying this aircraft without a complete condition inspection by someone very familiar with the RV-6.
I have found things that 99.9% of FSDO inspectors would have missed simply because they are not familiar with a particular model.
The most important thing that I've found on an RV-6 is 2 missing steel splice plates where the 2 wings mate. This is very critical and would never be noticed by someone not familiar with the RV-6.
The missing screws you mention are necessary for safe operation of the aircraft.
Good job on noticing this discrepancy. There are probably others. Make sure they are found.


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