IV fuselage repair - measurements

[motortommy 31]

I have a crashed and repaired fuselage. Although the plane has been in service flawlessly for years since then, I don`t like the workmanship of previous owner. Welding is awful, no splices and metric tubes were used. Further additional `improvements´ were made
Goal is to get the fuselage back in original state as much as possible referring to AC43.13

1. What is correct tube size (green) of the longerons. OD is 1/2", but unsure about wall?
2. Does anybody have a bare, undamaged IV fuselage handy and could help me with some measurements in case? No rush!

[1avidflyer 1983]

Tubing is .035" wall thickness.  JImChuk

[motortommy 31]

Thanks!
Unfortunately 4130 tubing is sold out at the moment (Germany)...have to wait.

Like more pics? Here is the bent mess...

previous repairman added triangle braces and steel stringers side and bottom, maybe to strengthen his welding skills

[Jimbo Bob 0]

I'm planning on measuring up my fuselage in the next few weeks. Mines badly repaired and has some corrosion. If it's not repairable I may build a new one from scratch. I'll post my drawings when I have them. 

[motortommy 31]

would be great to have some measurements as a cross reference…

Thanks!

[motortommy 31]

anybody out there with a genuine (not crashed) fuselage?

I want to replace some parts of the lower longerons due to improper repair. Questions:

- are the longerons one piece till the tail?

- is the longeron shape gently bowed (like #1) below or is the longeron divided in sections with straight tubes angled (like#2)

Hope you got what worries me... 

  

[1avidflyer 1983]

here are a couple of pics that probably show what you want.  JImChuk

[motortommy 31]

hmm, thanks!

Looks like a combination of bowed part in the middle and straight ends, tail and baggage area...

[akflyer 1427]

Bent tubes are pretty easy to straighten with a block of wood and a mallet.  Use a hard wood block and a router to shape the block to the tube OD.  A few good smacks with a mallet and its good to go.

[motortommy 31]

thanks for any help

Unfortunately I have to replace some sections due to wrong dia./poor welding...   

[Supermotive 49]

This guide may be helpful

Repair of Steel Tubing Aircraft Structure by Welding.pdf

[motortommy 31]

Thanks, great! I will study. Looks like a more modern abstract of

http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_43.13-1B_w-chg1.pdf