Which device prevents hydraulic fluid loss after a rupture?

• A. Hydraulic fuse
• B. Check valve
• C. Sequence valve
• D. Sensor valve

Answer: (A)

A hydraulic fuse automatically shuts off flow to prevent fluid loss when a line ruptures. It detects the sudden pressure change caused by a rupture and moves a valve to seal the line, isolating the ruptured section. In normal operation the fuse stays open, but the moment a rupture causes downstream pressure to drop, it reacts quickly to stop further leakage. This is crucial in aviation hydraulic systems to minimize fluid loss and reduce the risk of damage or fire. Other devices serve different purposes: a check valve prevents backflow but won’t automatically stop a rupture, a sequence valve controls the order of actuator pressures, and a sensor valve monitors conditions and signals rather than automatically isolating a leak.