I知 repairing a flap on my 1959 PA-22/20 and I'm trying to identify the kind of aluminum piper used. I know the industry changed the way they identified sheet aluminum alloys from a 2 digit identifier to a 4 digit identifier somewhere along the way. I知 looking for a cross reference of some kind that would help me translate the old identification to the newer alloy identification.

The only markings I can make out on the original part are;

3S

H14 (hardness)

24S-1

.02 (thickness)

Daryl