What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Aft canopy deck position along the longerons

Draker

Well Known Member
Happy new year everyone. Wish I could share in the happiness, but I just found what's possibly a catastrophic mistake I made on the RV, and wanted to share it. Obviously this is going to involve a long discussion with Van's, but I thought I'd start a discussion here to potentially prepare myself for the extremely bad news I have coming.

Long story short, it looks like I built the whole forward and mid fuselage around incorrectly bent and drilled longerons.

I'm at the point in the build where I'm disassembling the forward fuselage to prep the surfaces, dimple, and countersink them for riveting. While countersinking the longerons, something just didn't look right. The top holes I had drilled for the aft canopy deck were way too far aft. So I clecoed the longeron back to the mid-fuselage, and pulled out the F-721B aft canopy deck pieces. Lo and behold, the holes are indeed way too far back:

IMG_1408-XL.jpg


It looks like way back when I drilled the canopy deck to the longerons, I had the forward edge of it in the wrong position:

IMG_0931-XL.jpg


canopy%20deck-XL.png


How I made the mistake: The distance between "Beginning of Curve" and "End of Curve" is 30 27/32" which is almost exactly the length of the F-721B canopy deck piece, so I ASSumed that it was to be positioned between these marks.

So at the very least, I'm going to be ordering two more longerons, re-bending them both, and re-drilling them to the skins. As a side note, the holes in the longeron-facing aft fuselage skins are already dimpled so it's not going to be fun to re-drill those. But that's the least of my problems.

Unfortunately, as a result of incorrectly locating the canopy deck pieces, my longerons must have been bent in such a way that they align with the incorrect placement. As proof, when I lay the canopy deck piece against the longeron in the correct position, it does not match up with the curve of the longeron:

IMG_1412-M.jpg
IMG_1413-M.jpg


This means I have built the entire forward fuselage around incorrectly bent longerons. This may mean that I'm scrapping a fair bit of the front fuselage, too, likely at least the side skins.

To say I'm disappointed is an understatement. Please help me brace for the bad news from Van's. I'll be calling them pretty much as soon as they re-open from the holidays. And future builders, please learn from my carelessness.
 
Last edited:
Can you not "simply" replace the longerons? Most everything else is already match hole punched and should fit right back together.
 
Longerons

Agree. Everything else is prepunched. You may find the right size and type of angle at a local metal distributor. Check with Vans but I think it's 6061 T6 extruded angle. Note the curved inside vertex.
I have had to drill using a dimpled part before. Buy a section of brass tubing (1/16") that perfectly fits the dimpled hole. Use it as a drill bushing to keep the bit centered.#41 should fit.
Hope it works out.
 
Ryan and I spoke on the phone (we are both local NorCal builders) ... my assessment, too is it's just a longeron replacement. I'm hoping we can find a local supplier with stock so to nix the surely huge shipping charges...

We'll hear what Van's sez tomorrow.
 
Last edited:
Can you not "simply" replace the longerons? Most everything else is already match hole punched and should fit right back together.

Yea, I'm hoping that's it. If it's just new longerons I'm going to be relieved. All of the non pre-punched parts (lower longeron, aux. longeron, side skin stiffener angle, floor stiffeners) are in the forward area, which hopefully the incorrect bend does not affect.
 
Look at the bright side - bending the second set of longerons will be much easier than the first. Don?t ask how I know.
 
Ryan, I am sure you are in good company as there have been many mistakes made over the years in building many RV's. Someday you will look back and smile about it, I am sure. I have been where you are with other projects and honestly, the worst part was how bad I would beat myself up over it.

I do thank you for having the stones to stand up and show it. Just doing that will help some other guy down the road. That's what this forum is all about. Helping one another.

Good on ya! Ben
 
Yep I'm thinking just longerons too. Sorry to hear this happened. Keep us posted.
 
Ryan, I am sure you are in good company as there have been many mistakes made over the years in building many RV's. Someday you will look back and smile about it, I am sure. I have been where you are with other projects and honestly, the worst part was how bad I would beat myself up over it.

I do thank you for having the stones to stand up and show it. Just doing that will help some other guy down the road. That's what this forum is all about. Helping one another.

Good on ya! Ben

I represent the guy that this guy is talking about. I?ll note your experience to hopefully avoid the same mistake when I get to this part of the build. I?ve also chosen to order two extra longerons with my wing order because I don?t trust myself!
 
You might locate some from a builder who has a QB fuse but SB wings...the longerons are shipped with the wing kits, normally (as I recall). That'd perhaps save the mucho dinero it costs to ship them from Van's.

I ended up with 4 longerons because my buddy had done exactly that for his 8...fortunately, only need 2, but we had another set lying around in case.

Check around with your local builders, see who has what.
 
Finding new longerons is relatively easy. It's common 6061T6, just the length is a little annoying. I bought new longeron stock from my local Metals Supermarket (metalsupermarket.com) from what I remember. I ended up having the same situation as one of the others, where my countersink pilot nub broke and embedded into the longeron. That was heart-stopping for a few days while I sourced the new angle stock. But all is fine afterwards. Good luck.
 
Thanks for the tips, folks.

With the help of a fellow VAF builder I've located several local sources of 6061-T6 angle, so that's great. Turns out I bought an extra longeron while ordering the wing kit in case I screwed one up, so I only need to get one more. Too bad I didn't have 2.

Van's hasn't gotten back to me yet with a recommendation, but I bet their support team has a backlog of E-mails from over the holidays to get through.

I guess many of us have had one of those heart stopping "Oh s*** I screwed up my airplane" moments. Helps to step away, breathe, and do something else. We don't fly while stressed. Personal minimums apply while building too.
 
Finding new longerons is relatively easy. It's common 6061T6, just the length is a little annoying. I bought new longeron stock from my local Metals Supermarket (metalsupermarket.com) from what I remember. I ended up having the same situation as one of the others, where my countersink pilot nub broke and embedded into the longeron. That was heart-stopping for a few days while I sourced the new angle stock. But all is fine afterwards. Good luck.

Just to note for others on here who might not be aware...make sure it's *structural* aluminum angle, with the radiused inner angle, not square (non-structural). Lots of discussion about this on the forums if you search for it.
 
Van's confirmed: Just replace the longerons and bend/drill them correctly. Thanks, folks!

Mods, feel free to shorten the thread's title removing the "Potentially catastrophic mistake"--turned out not to be a big deal.
 
Just an update, in case anyone's curious. This story has a happy ending:

IMG_1547-M.jpg


The new longerons are bent, drilled, and ready to rivet! Thanks so much (yet again) for the input and encouragement. This community rocks!
 
Back
Top