Fuselage Welding

[astjp2]

Re: Fuselage Welding

Boeing actually welded aluminum with a torch Oxy/Hydrogen until 1996 when the flux was considered toxic and not cost effective. Go look at the tin mans website, what he can do with a torch is amazing on Aluminum.

Dave, It used to be there, but with all things FAA, it might have fell by the wayside. I need to find my copy of cam 18 and see what it says. I have a friend that teaches high school and university aircraft welding and he told me to pre and post heat too. It seems that depending on what expert you talk to, will give you thier version....

[rail]

Re: Fuselage Welding

Nope, the requirement is the same, the prewar's did have a few pieces of 4130, so I will treat it all as 4130 to be safe, if you use the torch, you are 100% ok if the welds are sound, if you tig, pre and post heat to a dull red and air cool, even on .028 wall. Tig is so hot in such a small area that the weld wont crack, but it can in the transition area between the heat affected zone and the rest of the tube. I actually bought a victor j-40 and a J-28 and a guy on metal meet had adapters to use a meco midget tips on a victor. I really enjoy the 40 because I have carpal real bad and my hands cramp after a few hours. Tig is beautiful and approved for NHRA and NASCAR, but Torch is the approved method for aircraft, unless you have approved data that says otherwise.

Kit fox migged their fuselages and I have see 2 that have crashed/ground looped and both had major structural failures at or near cluster welds. Some will argue but I am going to limit my liability and stick with torch for most of my repairs. I have a tig but its 1970's technology with no foot or thumb control so I limit what I weld with it. Tim

The base material and filler material melt at the same temps with Tig or gas.

I guess Boeing welds its components on a 57 million dollar aircraft with a gas torch?

Charles

[rail]

Re: Fuselage Welding

Wow,

I would assume the gentleman that worked for Vultee during WW2 conveyed false information to me about welding!

I would assume the Boeing, Douglas, Grumman and Lockheed aircraft Welding Process Specifications are incorrect!

I would assume Miller and Lincoln has incorrect data!

I would assume the major manufacturers of 4130, chemistry's data is incorrect!

I guess all the drivers that walked away from a 190+ mph crash never happened!

I would assume the AWS Welding Metallurgy book is incorrect!

I would assume SFI specifications are incorrect! (Chassis Construction)

I would assume that one of the gentleman that consults for AWS taught me bogus practices!

I should not get up in the morning and go the the R&D shop and build jet aircraft the fly at 400+ knots!

All of this has just been a practice in vain, all of the training from the certified schools are invalid, my experience is plain out worthless!

I am a practical person with an ability to learn from every person that I come in contact with. All of this information has came from experience and practice not theory!


"Lets talk about thin wall "normalized 4130" tubing, not 4130 heat treatable tubing and plate!"

Charles

Re: Fuselage Welding

Tim,

So why isn't this mentioned in 43.13-1B? (referring to TIG actually)

Dave

[astjp2]

Re: Fuselage Welding

Nope, the requirement is the same, the prewar's did have a few pieces of 4130, so I will treat it all as 4130 to be safe, if you use the torch, you are 100% ok if the welds are sound, if you tig, pre and post heat to a dull red and air cool, even on .028 wall. Tig is so hot in such a small area that the weld wont crack, but it can in the transition area between the heat affected zone and the rest of the tube. I actually bought a victor j-40 and a J-28 and a guy on metal meet had adapters to use a meco midget tips on a victor. I really enjoy the 40 because I have carpal real bad and my hands cramp after a few hours. Tig is beautiful and approved for NHRA and NASCAR, but Torch is the approved method for aircraft, unless you have approved data that says otherwise.

Kit fox migged their fuselages and I have see 2 that have crashed/ground looped and both had major structural failures at or near cluster welds. Some will argue but I am going to limit my liability and stick with torch for most of my repairs. I have a tig but its 1970's technology with no foot or thumb control so I limit what I weld with it. Tim

Re: Fuselage Welding

Hi Tim,

We small old airplane folks don't normally deal with heat treated parts or heavy sections or high strength issues.

Most work is on non heat treated and is thin wall.

Splices, patches, assemblies and weldments that are light, small and Sut<95Ksi.

That changes the process requirement doesn't it?

Dave

[astjp2]

Re: Fuselage Welding

The difference between a race car welder or industrial welder is his a$$ is not liable for the welds, as an a&p, mine is and that is why aircraft are pre and post heated in my shop.

If the part will be heat-treated after welding to achieve very high strength, a matching chemistry filler metal to the 4130 should be employed. Because of the relatively high carbon, a minimum of 200 degrees C, (400 degrees F) preheat and very slow cooling after welding should be used to avoid cracking. After welding, the part can be heated to 870 degrees C (1600 degrees F), quenched in oil or water then tempered back to say 370 degrees C (700 degrees F). A complex cycle, but this will result in a tensile strength of approximately 1380 MPa (200,000 psi). Since the weld is the same chemistry as the base material, it and the heat-affected zone will have the similar properties as the base material when heat-treated. All critical welds of this type should be inspected for internal soundness to assure they are free from cracks.

I have been an A&P for 23 years along with a full career in the aviation and racing industries; fabricating, machining, shaping, spinning, welding and heat treatment of structural metal components.

AWS certified in welding pressure vessels in the aircraft industry! Trained to Boeing, Douglas, Grumman and Lockheed (WPS) Welding Process Specification!

Welded chassis and pressure vessels for Toyota Racing Development to there engineering specs.

Please do not pre and post heat the aircraft structure no matter what process you use!!! No matter if it is mild steel 1020 & 1025, normalized 4130 or heat treated 4130!

All you are doing is inducing "shrinkage" into the structure!

As for A&P's, they should be smart enough to know when to rely on a welder in the industry, not some preconceived antiquated practice!

Attached is a picture of a few of the welding references I use in decision making about welding. None of these advise the practice of pre and post heat of thin wall tube aircraft structures!!!

[astjp2]

Re: Fuselage Welding

2 minutes on google...found this

http://www.netwelding.com/Welding%204130.htm

During the WW II era 4130 high strength steel was used for some aircraft components. At that time oxy-acetylene was the welding process of choice for many of these items. The preheat and slow cooling inherent with that process made welding the nominal 0.30 carbon steel relatively straight forward (assuming one could oxyacetylene weld!). However with more modern welding process like TIG and MIG, the cooling rates can be much faster and care must be taken to avoid forming high hardness and brittle Martensite on cooling transformation. On heavier sections preheat and post weld heat treatment should be used. With the proper post weld heat treatment strengths of 200,000 psi can be achieved with reasonable toughness by tempering the Martensite that forms in the heat treating process. However when welding race car tubing, preheat is not often used nor are the parts post weld heat treated.

Most of the tubing used for race car construction is referred to as normalized. This refers to the heat treatment and cooling rate the tubing was subjected to in manufacture. Most normalized tubing will range in tensile strength from 95,000 to 110,000 psi. This can be welded with the proper filler metals to achieve similar strengths. Although there are more weldable grades of steel (those with lower carbon content from 0.06 to 0.15) in the 100,000 to 115,000 psi tensile strength range readily available for plate and sheet, 4130 remains a commonly used grade for tubing. Just be sure to take the precautions noted when welding.

The following is extracted from an article I wrote for the American Welding Societies technical journal called "The Welding Journal". It has additional information to that presented in the publication. You can Click This Link to see the article:
taken from link below....

[astjp2]

Re: Fuselage Welding

I have seen pics of the oven that Stinson used, they post heated the entire fuselage in one piece.

An elderly ex IA in my area used to weld for Stinson during the war years and tells me they used to stick weld most of them.Also,I dont how reliable this is,but I was also told that Maule uses mig welding.A couple years ago I repaired a fuselage that a hangar had fallen on,and some of the welding had the bb,s and a few peices of wire at the weld that were not cleaned off.Maybe old repair,I dont know.Anyway,the way these aircraft are used in bush country i,ve never heard any horror stories about broken welds.Just my worthless two cents worth.I myself prefer and use the ox/acet method.

[rail]

Re: Fuselage Welding

I have been an A&P for 23 years along with a full career in the aviation and racing industries; fabricating, machining, shaping, spinning, welding and heat treatment of structural metal components.

AWS certified in welding pressure vessels in the aircraft industry! Trained to Boeing, Douglas, Grumman and Lockheed (WPS) Welding Process Specification!

Welded chassis and pressure vessels for Toyota Racing Development to there engineering specs.

Please do not pre and post heat the aircraft structure no matter what process you use!!! No matter if it is mild steel 1020 & 1025, normalized 4130 or heat treated 4130!

All you are doing is inducing "shrinkage" into the structure!

As for A&P's, they should be smart enough to know when to rely on a welder in the industry, not some preconceived antiquated practice!

Attached is a picture of a few of the welding references I use in decision making about welding. None of these advise the practice of pre and post heat of thin wall tube aircraft structures!!!

[mike lutz]

Re: Fuselage Welding

An elderly ex IA in my area used to weld for Stinson during the war years and tells me they used to stick weld most of them.Also,I dont how reliable this is,but I was also told that Maule uses mig welding.A couple years ago I repaired a fuselage that a hangar had fallen on,and some of the welding had the bb,s and a few peices of wire at the weld that were not cleaned off.Maybe old repair,I dont know.Anyway,the way these aircraft are used in bush country i,ve never heard any horror stories about broken welds.Just my worthless two cents worth.I myself prefer and use the ox/acet method.

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:

Hi Tom,

Yes Tom this is a good point indeed.

But one must also remember that while choosing this way it does allow you to select an acceptable method it does not prove that the alternate method is not also acceptable.

Its sort of why try to find the answer to an unncessary question. One might remain in a static state of welding technology with this method. That's not necessarily bad though.

Dave

[astjp2]

Re: Fuselage Welding

Forrest, what page of the type certificate says the welding must be Oxy/Acte? I have never see that once in any type certificate. Tim

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

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.....

Yes it is. You indicted electric welding process then as we discuss TIG you change the subject to MIG and reference a lot of anecdotal information.

There is nothing ridiculous about asking how one determined the root cause of a problem or giving valid technical references.

I suspect that all modern aircraft manufacturers use TIG on their chrome moly engine mounts and do not pre/post heat. I suspect that because I was told that by Miller Electric.

[Ragwing nut]

Re: Fuselage Welding

Do to the chromium content in 4130, concentrated heat will cause stress risers (embrittlement) in the grain of the metal and under proper circumstances such as an accident, it will fail along those stress risers unless the material is stress relieved. pre-heat is not as vital on thin wall materials, but post heat is an absolute.

1025 does not have chromium in it, so it is not as suseptible to embrittlement, but the issue becomes that you can make such a small pretty bead with TIG, there is not enough weld material to maintain structural integrity of the joint.

I build airplanes, custom cars, etc, and have gas torch, MIG, and TIG in the shop. However when I am working on aircraft, I always use the gas torch.