The scupper is an aluminum cup that is riveted with soft aluminum rivets.The small hole is for the tank opening.The scupper is needed to make a proper refueling.

 

In the aft fuel tank the cap is covered by this metal door.

And here's how we've done the thing.The metal door was done and painted by Laverda, "BENZINA Lt.70 AVIO" means Aircraft gasoline 70 liters.. On the right side of the scupper there's an hole for draining the fuel that has gone on the scupper.