25.973—Fuel tank filler connection.
Each fuel tank filler connection must prevent the entrance of fuel into any part of the airplane other than the tank itself. In addition—
(b)
Each recessed filler connection that can retain any appreciable quantity of fuel must have a drain that discharges clear of each part of the airplane;
(d)
Each fuel filling point must have a provision for electrically bonding the airplane to ground fueling equipment.