Welding your own fusalage

[Rob Swain]

My point was just about insurance, not regulations.

I stand corrected!

[rszemeti]

In a previous life, I used to own a largeish laser cutting and fabrication business. All my welding staff were "coded" to various levels, so I have some knowledge of the general principles involved.

I don't have the exact CAA welder qualification details, but this YouTube video gives a good idea of what is typically involved in an aerospace welder qualification test:

https://www.youtube.com/watch?v=zJQR1IY3jKI

Basically you need to qualify for each material type and the position you need to weld in (harder positions usually automatically qualify you for the easier positions, with the exception of "vertical up" ) so if you want to do alloy, and cro-molly, and some of it is tube and some is flat sheet ... you may have to do quite a few tests ....

I have the gear, and I'd love to tig up my own fuel tanks (and I think my tig skills may even be up to it) but I suspect the time/cost of getting the qualification may be significant ...

[Bill McCarthy]

Weld fusibe inserts make tube root welds a dawdle, if you can get hold of the the correct QA material.

[Brian Hope]

I have the gear, and I'd love to tig up my own fuel tanks (and I think my tig skills may even be up to it) but I suspect the time/cost of getting the qualification may be significant ...

Hi Robin, it is worth talking to LAA Engineering about getting approval for welding your own tanks. In the past, and I believe still, members could submit samples which, provided they were satisfactory, could enable them to weld their own parts for their projects. Gas and tig are OK, mig may well be a problem. I believe also that CAA approved welders are only required for critical components. Best to check with Engineering though as things do change and it's a while since I last needed to know about welding rules.
Rgds, Brian

[rszemeti]

Ah, that may be more do-able then.

I was planning to buy the structural/critical welded items from the kit maker, to keep things simple. If it was possible to weld the tanks, without sinking in a sea of paperwork, that is one part I would love to have a go at. Welding the tanks would be easy enough, and I could certainly submit samples. I'll discuss it with my inspector / LAA Engineering when it is a little closer to my event horizon.

There is nothing particularly tricky about welding Aluminium, if you start off clean, with the right process variables no more difficult than steel. I think a lot of people fail because they do not appreciate just how clean it has to be and just how quickly oxides will form. The right electrode, rod and a readily-weldable choice of base material also help ... after that it is just a steady hand and good eye sight!

[Basil]

In a typical fuselage where you have positioned the longerons in some type of jig, you are then adding a diagonal and then a vertical and then another diagonal. Where the longerons meet a vertical and a diagonal it is not possible to weld all the edges that touch, e.g. you can only weld just over half the circumference of the vertical to the longeron. Load analysis would suggest this doesn't matter as there is not much load transfer from the vertical into the longeron but is this normal welding practice when building a fuselage?