I have to laugh at the findings about Moorabbins proximity to the bay being an issue. The fleet I was involved with had spent 20+ years parked in the open at Moorabbin, and I never heard of a brake disc corroding to pieces, that included much time parked on the grass as well. That being said a few of the fleet rotated through point cook, and salt corrosion was very evident on electrical wiring that was exposed on those aircraft, but still no serious corrosion of things like brake discs.
The aircraft had been fitted with an unapproved aftermarket brake disc.
This sounds more like the reason. PS sounds like they were approved parts, just not for that aircraft, and sounds like they may not have had sufficient barrier coating, or at least the coating eroded fairly quickly in operation.
The operator’s aircraft were parked outside on concrete pads, surrounded by gravel and grass. Rain reportedly pools on and around these pads.
So the brakes often spent time partially immersed in water? I think that may be where the problem lies.
I feel like this agrees with what we were talking about on another page. People who operate light aircraft with little to no understanding of machines, and wonder why they go broke in a few years. Lets just park our investment worth a few hundred thousands dollars in a pool of mud and water.