PLASTIC COVERING ON 2024T3 SHEET 1

[1917Alby]

Can the plastic coating sheet alloy be left on the inside of a leading edge?
My thoughts are that it is not correct to destroy the aluminuium coating by scuffing it before treating it with alodine.
Alby

 

[kontiki99]

Is there bleed air deicing?

 

[rb1957]

? do you mean just for handling and forming, or for final installation ? i assume you're talking about clad Al. i'm not sure when in the part manufacturing process you'd "destroy the Al coating". in any case, Alodine application is an acceptable process for restoring the corrosion protection.

i think we remove the plastic film early in part manufacture, and alodine as required, and prime, and top coat as required. i'd be uncomfortable leaving the film on the component, mostly 'cause i think this is un-common practise (and has a bunch of unknowns).

 

[btrueblood]

Why didn't you put the coated (presumably better finished) side out?

 

[berkshire]

1917Alby (Aeronautics)
The plastic coating on aluminum sheet product (Blue Dragon or similar.) is there to protect the material during fabrication and material handling. It should be left on as long as possible to protect the sheets from scratching or over spray. It should be removed before installation.
It should not be exposed to sunlight, this will bond the film to the sheet making it just about impossible to remove. The material eventually goes brittle with age falling off in small pieces like old paint.
I would not leave it on a sheet in any place where its falling off would be a problem.
B.E.

 

[FieldTeam]

This is usually an acrylic coating that can be easily removed with an alkalyne stripper. Like berkshire noted, it can be very difficult to remove if left on. Heat turns it hard, crazed and does not look good. When it gets like this it provides no corrosion protection and is difficult to inspect as to what is going on underneath.

 

[kenvlach]

Worst of all, if left on, moisture eventually gets between the plastic and aluminum, and it doesn't take a rocket scientist to guess which one corrodes.

The film prevents marring the surface and corrosion during handling, storage and forming. Then remove it, and degrease, deox and Alodine the aluminum.