The AFCS YAW and COLLECTIVE channels are powered only from which DC bus?

• A. Right main DC bus only
• B. Left main DC bus only
• C. Both main DC buses
• D. Battery bus

Answer: (A)

Power to the AFCS yaw and collective channels is provided from a single DC source to ensure stable, isolated control power for these critical flight functions. They are fed by the right main DC bus only, which keeps them independent from the left main bus and from the battery bus. This avoids cross-feeding between buses and reduces the risk that a fault on one bus could compromise these essential autopilot channels. The battery bus is reserved for emergency or essential items, not for normal AFCS control channels, so it isn’t used to power yaw and collective.