Major screw up...

So, I think I might have really screwed up, and I'm still not sure what I did wrong...

I went to start putting the F-970 side skins on the fuselage today, and they do not line up with the F-904H.

It appears that the 904-H is not symmetrical, and I somehow missed that in the crappy directions, and of course got it upside down.

Since I drilled the holes backwards on the 904 spar they now don't match the skin.

Really at a loss on how to even begin to fix this one...

Thoughts?

-Dan

Apparently I've stumped (at least temporarily) Vans...

Talked with them this morning and they said they have never had this happen before (??), and they are thinking maybe I got the wrong parts (for the seven versus the nine).

I "think" I would have caught them having the wrong part number on them, but I wouldn't swear to it, and I did just have to get the F-939 and F-940 replaced because they sent me F-739 and F-740 by mistake..

Anyone else have any similar problems, suggestions, etc?

This one has me really worried. If I screwed up the center spar somehow, I'm not sure how to recover from that.

-Dan

I remember doing mine and thinking how easy it would be to make that exact mistake; I'm surprised that this has not come up before, and the instructions don't make note of it. What tipped me off was seeing that those pieces would not quite line up with the spar carry through in the opposite orientation.

I am guessing that you will need to start with some new 904-H's, and then possibly fabricate doublers for areas of the bulkhead flange that will require new holes if there are edge distance issues. Obviously as this is an important structure it will need to go through Vans, as you are doing, but like almost everything, I would be fairly confident there is a fix. Please keep this updated as I guarantee you won't be the last to do this!

Chris

Hi Dan, don't feel bad, I did the exact same thing on one side. To fix it I ordered a new 904H and I also had to order a new 904C/D. I then had to drill out the rivets to remove the 904C/D. Not bad but the new parts do not come with the spar bolt holes drilled so you need to drill those and that was the hard part. If you look at my blog post on the issue you will see what I mean.

http://www.darinanderson.com/2013/11/groan.html

Zuldarin said:

Hi Dan, don't feel bad, I did the exact same thing on one side. To fix it I ordered a new 904H and I also had to order a new 904C/D. I then had to drill out the rivets to remove the 904C/D. Not bad but the new parts do not come with the spar bolt holes drilled so you need to drill those and that was the hard part. If you look at my blog post on the issue you will see what I mean.

http://www.darinanderson.com/2013/11/groan.html

Click to expand...

Thanks Darin,

For some reason the guy I spoke with at Van's this morning kept insisting that this wasn't possible, and that the 904H is symmetrical...

I've got to send him some pictures when I get home in a bit, but it sounds like I'm going to be drilling out some rivets and replacing those parts...

So how did you wind up drilling the new holes for the spar bolts?

-Dan

been there, done that +1

Van's is correct that the 904H fits on either side, however, there is a front edge which has a slight bevel at the top of the plate. The hole patterns for the front column of rivets is not the same as the rear column, so if the beveled corner is pointed the rear when the 904H is drilled to the 904C & D's, the side skins won't match. I' ve never found this mentioned anywhere in the plans.

I had to replace the 904C & D's. Bolt the center section bulkheads tight and plenty of clecos in 904C & D's when carefully drilling the spar bolt holes so as not to damage bulkheads.

Good luck!

I think what I did was cleco it into place and then marked the hole positions through the spar. Then I removed and drilled it undersize followed by a session of filing the holes by hand to get them to the correct size. Sorry I don't have more detail.

I didn't want to run a drill bit through the spar because I was afraid I would bugger up the precision machined holes. I don't trust my perpendicular drilling skills.

Drill bushing

A drill bushing from mcmasters might be the way to get a smaller hole centered on spar holes. Then remove and drill out to full size.

Michael

Major screw-up

Hi Dan

To match up the bolt holes in the 904D, etc.,
- cut the top off the original 904D
- flatten the flange on the remaining piece
- cleco this to the correct new 904D (904D-R to 904D-R)
- use the original holes as drill/file guides

It will match the centre section perfectly. This way, you cannot damage the machined holes in the centre section. Also you put to good use the screwed-up piece and it won't be any good for anything else anyway.

Hope this helps.
Cliff RV9A - slooooooooow build
Chase, BC