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

1. (a) [Reserved]
2. (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;
3. (c) Each filler cap must provide a fuel-tight seal; and
4. (d) Each fuel filling point must have a provision for electrically bonding the airplane to ground fueling equipment.

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt. 25-40, 42 FR 15043, Mar. 17, 1977; Amdt. 25-72, 55 FR 29785, July 20, 1990; Amdt. 25-115, 69 FR 40527, July 2, 2004]