CS 25.973 Fuel tank filler connection

Each fuel tank filler connection must prevent the entrance of fuel into any part of the aeroplane other than the tank itself. In addition –

(a)Reserved

(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 aeroplane;

(c)Each filler cap must provide a fuel-tight seal; and

(d)Each fuel filling point must have a provision for electrically bonding the aeroplane to ground fuelling equipment.