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Slight Twist in the aft Fuse

Flyguytki

Flyguytki

Well Known Member
I started riveting the aft fuse today and hit a pretty big snag right at the end. Before Riveting I checked to make sure everything was straight and it was dead on. Now after about 75% of the riveting completed, I have a slight twist at the F-712 Bulkhead of about 2 degrees. I have tried to show this in the picture below but it is kinda hard to see. You can see the that bulkhead is twisted to the right which is giving it the 3 degrees down twist. I am confused for a few reason, Everything was straight before riveting, and everything was pre drilled, so where could the twist of come from? Next has anyone seen this before and how can it be fixed, Im not sure where to even start to fix this. The longerons do not run that far back to bring it back into square so will the Top deck be able too?? GRRR it was such a great day until this.


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Aft Fuselage Twist

I had a twist slightly worse than this on my 8 when I clecoed my fuselage together.

I looked at it from every angle and discovered that the aft bottom skin had been formed wrong and was causing the twist. Van's replaced it. Problem solved.

Cleco the deck in place and see if it fixes it...but don't be afraid to double check the parts.

Good luck,
Mike
 
I had trouble getting the twist out. I could not clamp the aft deck and keep it straight. I cleco'd on the aft top skin and it was almost perfect. clamped the aft deck and it was perfect.
 
OK.. I had the exact same problem only a few months ago working on my 7.. At first I thought it was the J Channel interfering with the aft most bulkhead in a weird way. Then I realized that wasn't the problem and it had to do more with the tail spring.. When you first drill the fuse the tail spring isn't there, then later it is there, then when you go to torque the bolts down and install the keeper rivets, it does some weird things because it isn't exactly straight.. Then to make things worse at this stage you can't take it out..

All in all, the way I finally solved it was to drill out my keeper rivets, then straighten everything out and re-drilled for larger diameter keeper rivets. After that my rear fuse was straight as an arrow.. You can read my two entries below, they somewhat explain what I went through. In particular the second Link below was my solution..

http://www.704ch.com/2010/08/tail-cone-troubles-with-fit.html

http://www.704ch.com/2010/09/tailcone-i-am-just-gonna-claim-victory.html
 
Flyguytki said:
...The longerons do not run that far back to bring it back into square so will the Top deck be able too??...
Click to expand...

What?!? On my RV-7 the longerons run all the way back.

I also had a slight twist, but I was able to take it out when drilling/clecoeing/riveting the top deck to the longerons.
 
Sparky said:
What?!? On my RV-7 the longerons run all the way back.

I also had a slight twist, but I was able to take it out when drilling/clecoeing/riveting the top deck to the longerons.
Click to expand...

I had the same thought.

Also, I would not be riveting anything at this phase without the longerons clecoed in place.
 
Ah your right about the longerons they do run full length I don't know why I was thinking they stopped at the 711 bulkhead. My first order of business will be to drill out the keeper rivets in the tailwheel mount since that was the only change in-between clecos and riveting. As far as not riveting until the longerons are in, I'm just following the instructions it says to rivet everything together up to the last j- channel so you can bend the skins back enough to get the longerons in. Thanks again for the help, I'll post back tonight with the results.

-David

Ps: OT anyone know how to add a word to an iPad dictionary? Every time it type longeron it changes it to longhorns if I don't hit the little x on it.
 
The Twist is GONE!!! The keeper rivets in the tailspring mount is what was holding holding the aft bulkhead a bit to the left. After they were drilled it the bulkhead immediately straightened out. I am going to hold off on enlargening the holes and putting new rivets in until I have the longerons and Top Aft deck clecoed in.

Thanks for all the help once again!
-david
 
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