Fuselage Welding

[Forrest Barber]

Re: Fuselage Welding

This getting ridiculous, I have first hand experience with the breaking right outside the weld on the mig welded stuff. Numerous experimentials that were done at home have had problems. The approved methods for the Taylorcraft are part of the TC ; the "new" factory had tried for deviations and I think a few of us have seen "those" struts and fuselages, what a mess. I am now out of the discussion and back to my torches for any repairs on 1025 or 4130 or the 1010 struts too!! I agree that MIG process in a controlled situation is very good, we have a lot of fab shops around us doing award winning motorcycles & cars , just don't use it for repairs on older aircraft. All this in MHO. Back to the big snow Event in NE Ohio.....

Re: Fuselage Welding

I have seen first hand the problems of not pre and post heating 4130 tubing. In the late 60's I was into circle track racing and a tube frame modified which looked beautiful lost control and rolled several times. Pieces of the frame came flying out of the dust cloud and the tube had broken like glass next to a lot of the welds. Enough of the cage remained intact that the driver was not seriously hurt but that is about all that was left of that car. He was lucky in that the welds that would have killed him did not fail. The welding was done with at that time state of the art electric tig or mig welding equipment. There are newer welding materials and equipment which work better without pre and post heating than the old gas welding without treatment but there is still nothing like doing it right.

Hi Lyn,

How did you determine that lack of pre/post heat was the root cause?

Dave

[mohawktipi]

Re: Fuselage Welding

After I posted my first response, it occured to me that this situation might best be solved by Occam's Razor "when you have two competing theories that make exactly the same predictions, the simpler one is the better."

Since we know that gas welding works and the TIG welding leaves many questions unanswered (in this situation) why not use the time proven gas method. :hammer:

[mohawktipi]

Re: Fuselage Welding

O.K. it's not a Tcraft but I just purchased the plans for a Sonerai II LS. In reading through the material, it stated that TIG welding would require that the 4130 tubing be heat treated to restore strength properties. They strongly advise gas welding.

[N96290]

Re: Fuselage Welding

According to manual 18, the bible.

Re: Fuselage Welding

I have seen first hand the problems of not pre and post heating 4130 tubing. In the late 60's I was into circle track racing and a tube frame modified which looked beautiful lost control and rolled several times. Pieces of the frame came flying out of the dust cloud and the tube had broken like glass next to a lot of the welds. Enough of the cage remained intact that the driver was not seriously hurt but that is about all that was left of that car. He was lucky in that the welds that would have killed him did not fail. The welding was done with at that time state of the art electric tig or mig welding equipment. There are newer welding materials and equipment which work better without pre and post heating than the old gas welding without treatment but there is still nothing like doing it right.

"Right" according to who?

[N96290]

Re: Fuselage Welding

I have seen first hand the problems of not pre and post heating 4130 tubing. In the late 60's I was into circle track racing and a tube frame modified which looked beautiful lost control and rolled several times. Pieces of the frame came flying out of the dust cloud and the tube had broken like glass next to a lot of the welds. Enough of the cage remained intact that the driver was not seriously hurt but that is about all that was left of that car. He was lucky in that the welds that would have killed him did not fail. The welding was done with at that time state of the art electric tig or mig welding equipment. There are newer welding materials and equipment which work better without pre and post heating than the old gas welding without treatment but there is still nothing like doing it right.

[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

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

[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.

[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).

[astjp2]

Re: Fuselage Welding

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

[rail]

Re: Fuselage Welding

Ac43.13

What paragraph from section 5 ?

Charles

[rail]

Re: Fuselage Welding

Cracked aluminum cast valve covers!

[astjp2]

Re: Fuselage Welding

Ac43.13