What typically activates the safety feature of hydraulic fuses?

The safety feature of hydraulic fuses is primarily activated by a sudden drop in pressure within the hydraulic system. Hydraulic fuses are designed to protect the hydraulic circuit by limiting the flow of hydraulic fluid if an unexpected pressure loss occurs, which could indicate a leak or other failure in the system. When the pressure drops significantly, the fuse will activate and block the flow to prevent further damage or loss of hydraulic function. This is crucial for ensuring the safety and operational integrity of aircraft systems, as maintaining hydraulic pressure is essential for controlling various flight and landing operations.

While other factors such as excess oil temperature, electrical short circuits, or manual overrides are important considerations in a hydraulic system, they do not directly trigger the activation of hydraulic fuses. Instead, the sudden drop in pressure is the key condition that initiates the safety action of these components, making it the correct answer.