Identify the role of external power in the UH-60 electrical system.

• A. External power provides an alternate source when engine-driven generators are unavailable.
• B. External power is never used.
• C. External power powers only avionics.
• D. External power automatically powers the rotor.

Answer: (A)

External power provides an alternate electrical source when engine-driven generators are unavailable. In the UH-60, power normally comes from generators driven by the engines, but on the ground or if those generators are not supplying power, a ground power unit can connect to the aircraft to feed the electrical buses. This lets you run lights, avionics, radios, instruments, and starting equipment without draining the battery or needing the engines running. It does not power the rotor or drive it electrically—the rotor is powered by the engine and hydraulic systems, not by external electrical power. External power is used as a general backup source for the aircraft’s electrical needs, especially during ground ops or maintenance.