If your plywood fan deck looks like this it is going through a deterioration process called delamination.
Delamination is in progress when the top layers of plywood break down and peel off.
Delamination is caused by ultraviolet attack and is aided by overspray, wet/dry cycles, snow, ice and rainfall, etc.
After several layers have peeled away, replacement is often called for before this condition becomes a safety hazard.
