RV-6A Wing spar bolt sizes

[chriscencula]

I'm starting work on my RV-6A fuselage.
In looking at the plans (DWG 59), I see reference to some AN4 bolts that hold the landing gear weldments to the lower spar barstock... My spars came pre-drillled, but all the holes (with the exception of the most inboard holes and two in a 'spreader' piece of ~3/4x3/4 barstock) are 3/16th.

I'm wondering if anyone else had this discrepancy???

If so, what did you do about it?

My wings were received in 1996 and were some of the earliest pre-punched (skins only); they weren't 'ordered' as pre-punched, they just came that way as a 'surprise'...

Not sure how to post the 'scanned' .PDF of my drawing 59...

Thanks,
Chris

 

[flion]

No discrepancy. Check drawing 15; those holes are initially drilled for AN3 bolts. An RV-6 doesn't have the landing gear mounts there and does not use those AN-4 bolts. The instructions in section 8 under the heading FITTING THE RV-6A LANDING GEAR MOUNTS has the following several paragraphs down: (emphasis mine)

A total of 16 holes are needed in the spar contact flanges of each gear mount weldment. Twelve of these holes (refer to DWG 59) are to be 3/16" and are to be pilot drilled in this manner. Four holes in each of the mounts must be enlarged to 1/4". These can be drilled at this time. First, drill 3/16" from the rear, forward through the steel plates. Then, from the front side (which is more accessible) enlarge the holes to 1/4" diameter.

Rather than following Van's instructions to use a bushing, I enlarged the appropriate holes in the spar to 1/4" and then used pilot drills I got from Avery to drill the pilot holes in the mount. Then remove the mount and enlarge the pilot holes slightly undersize. Finally, replace the mounts and jig everything up again and use a reamer to finish the holes to match the spar.

 

[chriscencula]

Hi Patrick,

Thanks for the reply!
Guess I better take a look again through the text portion of the manual...

I'm a *long* ways from taking this step, but I noticed the hole size discrepancy while 'looking ahead' in the plans... There are so many 'gotchas' on the RV6 assembly in terms of things that might not fit well or interference issues trying to drill/rivet etc that I'm trying to look ahead as much as possible so as not to get in a corner and have to do something either : A) Poorly because of access or B) Where I have to disassemble in order to make forward progress.

Thanks,
Chris

 

[Bob Axsom]

You Have the Correct Perspective

Hi Patrick,

Thanks for the reply!
Guess I better take a look again through the text portion of the manual...

I'm a *long* ways from taking this step, but I noticed the hole size discrepancy while 'looking ahead' in the plans... There are so many 'gotchas' on the RV6 assembly in terms of things that might not fit well or interference issues trying to drill/rivet etc that I'm trying to look ahead as much as possible so as not to get in a corner and have to do something either : A) Poorly because of access or B) Where I have to disassemble in order to make forward progress.

Thanks,
Chris

I cannot imagine how you got prepunched holes in a 1996 skin anywhere on the airplane. I picked up my kit with a rented Budget 24' truck on November 11, 1996. There were no prepunched holes and it would worry me a lot about the accuracy - those were more primitive times and you could only be sure of what you did yourself. Don't get me wrong it was a wonderful kit and airplane but you REALLY have to look ahead and force yourself to understand the purpose of any irreversible action BEFORE you take it. It is worth the effort - I have been flying ours for 7 years now. Photo of the Blue Bird in cruise configuration:

Bob Axsom