A-1148 "Tailwheel Spring Upper Support"

[mhorowit]

Re: A-1148 "Tailwheel Spring Upper Support"

Here's the parts that went into the longeron repair on my airplane.... and the section that we replaced.

Terry - I've now welded that cluster two ways:
1. tacking all the tubing to the bracket, then welding and
2. tacking just the tubing to each other, welding except for the bottom (which if welded, would cause the tubing not to lie flat on the bracket). Welding the bracket to the tubing would be the second step.

The second method seems to allow me to more easily weld the cluster; I'm thinking less heat is being wicked away

How did you do yours? Any reason I shouldn't do this in two steps? - Mike

[barnstmr]

Re: A-1148 "Tailwheel Spring Upper Support"

Sounds like your 1st method is similar...
I recommend you position all the parts in place and hold all together with clamps first. Then slowly tack here and there while keeping things aligned. As you begin the serious welding you'll start getting a feel for how the assembly wants to move around while heated.. so alternate areas to even out (or counteract) the warpage. Take your time and don't allow things to heat soak too much. Weld... Stop.... check alignment... cool.... Weld... stop... check... cool...repeat....repeat
Are you using TIG or oxy-acetylene?

[mhorowit]

Re: A-1148 "Tailwheel Spring Upper Support"

Sounds like your 1st method is similar...
I recommend you position all the parts in place and hold all together with clamps first. Then slowly tack here and there while keeping things aligned. As you begin the serious welding you'll start getting a feel for how the assembly wants to move around while heated.. so alternate areas to even out (or counteract) the warpage. Take your time and don't allow things to heat soak too much. Weld... Stop.... check alignment... cool.... Weld... stop... check... cool...repeat....repeat
Are you using TIG or oxy-acetylene?

Oxy
This cluster is amenable to being approached as a series of different techniques, each of which can be practiced. For example - there are parts which are no more difficult to weld than a tubular "t" joint, then there are places where you have to increase the heat to get into the 'crotch' of the two longerons, then there is the really difficult weld where the longerons meet the floor of the bracket; the angles of the metal pieces are such that you need to get the torch in deep (maybe 1/2") and you don't want to overheat the sides. I can duplicate that situation with some more scrap so I don't have to reweld the whole cluster; just practice the technique I need for that 1" part.

Came home and welded a practice cluster, duplicating what I'll do for the tailpost, but leaving off the bracket. It was beautiful. Something went right and I'm really pleased with the results. Sure sign the next one will look like a dog's breakfast, but there is hope and these small triumphs keep me going. - Mike

[wmfife]

Re: A-1148 "Tailwheel Spring Upper Support"

The springs are wrapped with one continuous layer of "felt" (rubber baffle material on mine...) that's doubled at the top. I am completely re-doing the set on mine as it arrived with a mis-matched springs set (...and a shimmy that wouldn't quit! -Basically I had one spring carrying the load where two were supposed to be and NO FELT at the top...)
You need more at the top to absorb the landing load and protect the structure. The shop had replaced the felt with rubber but only put it on the BOTTOM!

[Forrest Barber]

Re: A-1148 "Tailwheel Spring Upper Support"

Actually it only on the top, leather works too!

[wmfife]

Re: A-1148 "Tailwheel Spring Upper Support"

"A-50A PAD 2 REQ."
-BC12D Service Man.

(...But Rob Lees' pics were so much sharper.)
Seems it did take a lot of washers to get it all to fit.
So I didn't need to change the AN bolts then. Hm.