Fuselage Twist Tolerance Question

[snoopyflys]

Anybody experienced this while working on the aft fuselage?

Prior to drilling the SB aft fuse components, the overall twist measurement between the F-706 and F-712 bulkheads was dead on center with the tooling holes. Now after drilling, disassembling, deburring, dimpling...(the stuff we all love to do), I reassembled and a final twist check revealed a slight twist for and aft. I can remove this "new twist" with slight very light hand pressure or shimming the fuse left-side near the F-706 bulkhead and on the right-side of the F-712 bulkhead.

Since the plans call for no twist in the fuse prior to drilling, will this "new twist" just work itself out while riveting or lock it in place? Is there a level of acceptable post-drilling twist tolerance or am I worrying about something that the top skin will correct when its rivited in place?

FUD (Fear, Uncertainty, Doubt) has struck again .

 

[alpinelakespilot2000]

Not sure exactly what stage you are at, Dan, but so long as you haven't drilled your aft deck yet, you're probably OK. When you clamp that for drilling you'll be able to take out most, if not all, of the twist that remains. Then, once you rivet that aft deck in place, everything is fixed forever, for good or ill. Hope this helps.

 

[AltonD]

Mine had a pretty good twist in it that was givin me fits to take out. I finally cleco'd the aft skin in place and it was almost perfect. I pulled it out and clamped the aft deck for a perfect zero.

 

[jjconstant]

I found that I would occasionally cleco something together multiple times for whatever reason and some of these times it would fit better than others. I established that on large parts, the order you put the clecos in affected the fit so I figured out the best order of clecoing for fit on any given part.

Just my experience.

Jeremy Constant
Rv7A 110 hrs

 

[snoopyflys]

Thanks for the feedback.

I am at the stage of riveting the aft fuselage together and I am making my final checks before I commit. The plans call for the riveting sequence to start from the aft end of the fuselage. I have been clecoing from forward-to-aft end of the fuselage. Clecoing sequence has played a role in things lining up for me in the past. So that may be be playing some part here.

Since my original posting, I decided to cleco (loosely) the F-775 top skin to the aft fuselage assembly to see how much, if any, of the twist would be removed. While cautiously optimistic, clecoing the aft top skin in place did in fact take most of the twist out .