CASA is incapable of building an "adequate" maintenance program. Comprehensive? Expensive? Both yes. "Adequate"? No.
For me, an internal wash with epoxy primer is adequate, coupled with a design that is fail safe or now " damage tolerant" so that blind Freddy can see he has a problem before bits fall off.
To put that another way; remind me how many corrosion related catastrophic failures of welded tubular structures have we had compared with all the other sources of accidents?