Identify two main sources of electrical power for normal operation on a narrowbody aircraft.

• A. Battery only.
• B. Engine-driven generators and an APU or external ground power unit.
• C. Solar panels.
• D. Hydraulic pumps.

Answer: (B)

Normal operation on a narrowbody aircraft is powered by engine-driven generators supported by an auxiliary power source when needed. The generators attached to the engines supply most of the electrical energy in flight. On the ground, or when extra power is required, the auxiliary power unit can provide electrical power, and there’s also the option to connect an external ground power unit to supply power without starting the engines. Batteries are mainly for starting and backup for essential loads, not for continuous normal operation due to limited capacity. Solar panels aren’t used for primary power on these aircraft, and hydraulic pumps are part of the hydraulic system driven by the aircraft’s power sources, not a primary source of electrical energy.