Fuselage Welding

[Blade]

I have some repairs to do to the fuse. Since the old 1940 B models were gas welded, do repairs on the fuse need to be done the same way or can TIG welding be used?

[Mark Julicher]

Re: Fuselage Welding

TIG is fine.
Just make good welds. An experienced welder is the key to success, not the equipment used.

[Ragwing nut]

Re: Fuselage Welding

TIG welds must be post heated to prevent embrittlement. not as bad of an issue on prewars since they are 1025 and not 4130

[astjp2]

Re: Fuselage Welding

Pre and post heat for tig, I would rather gas, less requirement for tight fitment of the joints. Tim

[Forrest Barber]

Re: Fuselage Welding

Hi Mark , I answered your direct e-mail , certified Taylorcraft repairs require Oxy-Acet . It is up to your A&P and IA if he ( they) wants to deviate, when the weld fails and causes a death I may be on the side of the deceased parties family . pre and post is correct. I always wonder why, just do it with the torch in the first place.

[astjp2]

Re: Fuselage Welding

Forrest, the weld is so small and the heat is so intense that you need to pre and post heat to spread out the expansion and contraction....I have seen4130 crack adjacent to tig welds, Tim

[rail]

Re: Fuselage Welding

Please research the materials and processes you are welding!

I have welded in the Aircraft and Racing industries for the past 23 years. I have not read a (WPS) Welding Process Specification that required pre and post heating of thin wall "mild" 1020 & 1025 steel and "normalized" 4130 alloy steel!

If any one can provide or produce the Taylorcraft dwg and process spec. that requires pre and post heat, I will stand corrected!

Charles

.030" sheet steel teardrop step welded to .065" aero tubing!

[astjp2]

Re: Fuselage Welding

Ac43.13

[rail]

Re: Fuselage Welding

Cracked aluminum cast valve covers!

[rail]

Re: Fuselage Welding

Ac43.13

What paragraph from section 5 ?

Charles

[astjp2]

Re: Fuselage Welding

I am trying to find it, I do know it was there before....

[bashibazouk]

Re: Fuselage Welding

4-1

c. Normalizing is heating steel to approximately 150 °F to 225 °F above the steel’s critical temperature range, followed by cooling to below that range in still air at ordinary temperature. Normalizing may be classified as a form of annealing. This process also removes stresses due to machining, forging, bending, and welding. After the metal has been held at this temperature for a sufficient time to be heated uniformly throughout, remove the metal from the furnace and cool in still air. Avoid prolonging the soaking of the metal at high temperatures, as this practice will cause the grain structure to enlarge. The length of time required for the soaking temperature depends on the mass of the metal being treated. The soaking time is roughly 1⁄4 hour per inch of the diameter of thickness (Ref: Military Tech Order (T.O.) 1-1A-9).

[rail]

Re: Fuselage Welding

4-1

c. Normalizing is heating steel to approximately 150 °F to 225 °F above the steel’s critical temperature range, followed by cooling to below that range in still air at ordinary temperature. Normalizing may be classified as a form of annealing. This process also removes stresses due to machining, forging, bending, and welding. After the metal has been held at this temperature for a sufficient time to be heated uniformly throughout, remove the metal from the furnace and cool in still air. Avoid prolonging the soaking of the metal at high temperatures, as this practice will cause the grain structure to enlarge. The length of time required for the soaking temperature depends on the mass of the metal being treated. The soaking time is roughly 1⁄4 hour per inch of the diameter of thickness (Ref: Military Tech Order (T.O.) 1-1A-9).

4-1, par. c is in Section 1, Identification Of Materials. Section 5 of chapter 4 is the process.

4-1 c. states, heated uniformly throughout in a furnace; avoid prolonging at high temps, causes grain structure to enlarge.

[Guest]

Re: Fuselage Welding

On page 1 of ac43.13-1b you will see that Richard Finch is given credit. He participated in the welding section of chapter 4.

Chapter 4 recognizes gas, mig, tig, stick and resistance welding as acceptable methods with no mention of pre/post heat.

Richard Finch is also the author of many welding books, google him and welding and you will see.

In his book called "Performance Welding" on page5, page 56 and page 75 he refers to the pre and post heating practice as "erroneous", "old wives tails" and "mistakes" respectively.

Additionally on page 5 he mentions his work on ac43.13.

I read that book around 2003.

I report you decide.

Dave

[Hank Jarrett]

Re: Fuselage Welding

From a practical perspective only two things matter; will your A&P/IA say it's legal and do YOU think it is safe.
This is a great discussion for the second (and more important) part. If your A&P/IA won't accept it, it is illegal, it doesn't matter if it is safe/correct or not. Just try and find an A&P/IA who will over ride another one!
The more important part (once your mechanic says it is OK) is for YOU to be well informed and make the final decision if YOU will accept it.
I avoided the whole problem and gas welded all the repairs.
Hank