Powdery Rot ..... call it what you want, it's simply Corrosion. The same white powder will show on any Aluminum object that corrodes, just as rust forms on steel . Just as real aircraft are prone to this, so are many late model cars and trucks with aluminum body panels. Some Ford models here in the US have been notorious for poor prep of the aluminum hoods (or Bonnets as they would call them across the pond
). My sons '05 Ford Mustang had this issue, white powder "Corrosion" perforating the hood in many spots. OTOH.... i wasn't aware Phoenix made models of Aluminum as i don't own any, they must be pretty light.