Aircraft fuel tank

Safety aspects of aircraft fuel tanks were examined during the investigation of the 1996 TWA Flight 800 in-flight explosion accident.

The weight of the tanks and fuel counteract wing bending loads during manoeuvres and reduce fatigue on the spar structure.

External tanks are commonplace on modern military aircraft and occasionally found in civilian ones, although the latter are less likely to be discarded except in the event of emergency.

[1] Drop tanks were originally designed to be jettisoned when empty or in the event of combat or emergency in order to reduce drag and weight, increasing manoeuvrability and range.

Modern external tanks may be retained in combat, to be dropped in an emergency and are often not designed for the stresses of supersonic flight.

[6] The aircraft engines are also capable of getting fuel via suction in the result of a failure in the backup pumps, though this produces less reliable thrust.

[7][6] The placement reduces the stress on the wings during takeoff and flight, by putting the heavy fuel directly inside the source of lift.

[7] Putting tanks in the main wings rather than near the tail or nose also reduces the amount of weight that is off-center from the plane's center of gravity, and which changes as it flies[7] and which would make the aircraft less efficient by requiring increased use of elevators.