Aircraft bypass pins are used to bypass hydraulic system steering on aircraft, allowing for steering to be controlled completely by the pushback tug. Failure to use a bypass pin when the hydraulic system is activated can lead to equipment damage and operator injuries, as well as damage to the aircraft. Since some aircraft cannot bypass hydraulic steering without shutting down the entire hydraulic system, a bypass pin saves time and makes towing easy.
F72735-13 is used on various 737 Classic aircraft as a safety lock pin to lock out all hydraulic pressure to the nose landing gear steering actuators during aircraft towing operations.