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RV-3 Spar Mod

M

mmcdonald

Active Member
Working on Van's CN-2 spar mod on an RV-3 with 1/8" rivets.


The mod requires replacing some of the 1/8" rivets with 3/16 rivets on the lower spar section. I do not have wing tanks so access to the back of these rivets with a 4 lb bucking bar is limited.

Can you substitute an AN-3 bolt, washer and nut (of proper length) for the 3/16" rivets where access is limited?

Any help greatly apprciated.
 
Call Vans in the morning. The CN-2 mod is their engineering, it would be best to get their opinion.

In my opinion. :)
 
Take what Van's tells you with a grain of salt-- the person I talked to at Van's was sure there is only ONE mod, but in reality there are TWO mods for each wing type that need to be done-- one for the main spar and one for the root rib/rear spar attach. I think Paul Dye commented once that the only person at Van's who's built a 3 or knows much about them anymore is Van himself.

I'm sure you must have read all this, but if not:
http://www.romeolima.com/RV3hq/Info/info.html#WingTypes

Sure would appreciate some in-process photos of your mod! :D
 
You do have to talk to the right folks at Van's when it comes to the -3. Most have no experience with it (as Katie says), but a few of the more thoughtful folks can at least give you some guidance to see if your ideas are valid. The -3 does share similarities to the -6, so it is not completely foreign. If you take the stance that you are not lookign for a "Factory Position", but just some discussion on principles, you'll do better!

Paul
 
Vans Response, Do not use bolts

Had e-mailed Ironflight to take this thread down since I was able to properly
install all 3/16 rivets in lower spar.

Recieved E-mail from Joe at Vans with the following:


Mark,

In this case you should not substitute a bolt where a rivet is called
out.

It is the better to use rivets throughout because they will fill the holes
completely, even somewhat imperfect holes. Use of a bolt that is installed with
anything
other than a drive fit allows for some clearance and this clearance is the problem.

If there is any clearance in a bolt hole of a joint in which both rivets
and bolts are used the rivets would take the entire load before the bolts see any
(shear) at
all, that is until there is some give in the structure (not desirable) to
close up the clearance.

Having said this, we could make an exception for a drive fit of the bolts.
A drive fit is an interference fit where the shaft diameter is in this case about
.001
larger than the hole diameter.

Keep in mind that if the hole is drilled too large and it is not necessary
to drive the bolt into the hole then a 3/16 rivet must be used. Do not use bolts
larger than
3/16.

Perhaps another option which would still allow for the use of rivets would
be to peel back the lower surface of the nose skin to access the front face of the
spar,
like what was done on the main skin.

I hope this helps.

Thanks

Joe Blank
Builder Support
Vans Aircraft Inc.
 
KatieB said:
Take what Van's tells you with a grain of salt-- the person I talked to at Van's was sure there is only ONE mod, but in reality there are TWO mods for each wing type that need to be done-- one for the main spar and one for the root rib/rear spar attach. I think Paul Dye commented once that the only person at Van's who's built a 3 or knows much about them anymore is Van himself.

I'm sure you must have read all this, but if not:
http://www.romeolima.com/RV3hq/Info/info.html#WingTypes

Sure would appreciate some in-process photos of your mod! :D
Click to expand...

The person I talked to at Van's (don't recall the name) was aware of the two mods and I specifically asked for CN-2 as I already have all the information on CN-1. I have not received the packet as yet so I will let you know if it's the right stuff. I will try to post some pics if I can.
 
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