Will need help... my BD-12 was affected by Milton

[Hank Jarrett]

Giving this a bit more thought, I believe there is a relatively easy solution (especially if you know someone with access to a CNC or even manual milling machine).

for the two standard hinges, duplicating the magnesium castings by machining from 2024T3 bar stock would be stronger, similar weight, and more corrosion resistant.

The aileron bellcrank/hinge assembly would be less straightforward but still a relatively easy candidate for CNC duplication.

I had considered making door handles from solid (using hand tools) but in the end found two acceptable ones.

All these magnesium parts are getting hard to find so machining from solid might be an option.
S

Only problem is getting the FAA to approve the material change. ESPECIALLY on a part in the control system! You will need a DER to do the engineering analysis and then he will need to convince the Feds to allow it. NOT going to be easy, especially compared to making one from welded steel using the pre war welded ones that are already approved for use on pre and post war planes.

Hank

[Scott]

Understand the problems with approvals if you go that route. My thoughts were just about owner produced parts.

2024T3 is a much stronger more durable material than cast magnesium. Common and acceptable practice to use a higher grade material to fabricate replacement parts. Using 4130 in place of 1025 for example, or 2024 in place of nicral, or 032" in place of 025" etc..

I would certainly have no problem signing off a certificated aircraft with owner produced parts duplicated as described.

The advantages over steel are clear - no jigs needed, more consistant parts, that are easier to produce once the cnc file is created, and weight similar to the original magnesium ones.

Anyway just a thought.
S

[braol]

Too bad we're not the Super Cub community...someone would have produced a titanium part by now...with a bushplane option of some sort I'm sure.

[Schlitt]

I'm a DER that does this sort of thing quire often for a living, but with more critical items on helicopters. Although a fixed wing mechanic, I lack the fixed wing DER rating to help you guys out here with a directly approved alternate; however, I can sometimes grease the skids with one of a few FSDO contacts for surrogate field approvals using the same level of data package that I would normally write within my delegation. Replacements for magnesium are some of the easiest to substantiate substitutes from 2024.... even if there are forging grain flows to consider. 6061 even better, for corrosion protection. Its probably not financially worth the while to develop a data package and champion a serialized approval, but perhaps instead a collective STC effort. Are there enough folks that want these parts? Maybe a collaboration can make this worth while. I no longer fly a BC-12, but can sympathize with keeping antiques alive. Anyone have pre-war Chief Shinn brake parts or a spare Corsair wing lying around that they would sell me?