If there is a loss of engine power, the primary system fails, or a failure of the battery bus the emergency hydraulic system is used to operate the _________________.

• A. Landing gear, main gear inboard doors, and flaps
• B. Landing gear, flaps, and speed brake
• C. Landing gear, landing gear doors, flaps, and speed brake
• D. Landing gear, main gear doors, nose gear doors, and flaps

Answer: (A)

When primary hydraulic power or electrical power is lost, the aircraft relies on a backup hydraulic source to keep the most critical systems available for landing. The emergency (standby) hydraulic system provides a limited but essential set of actuations, enough to extend or retract the landing gear, operate the main gear doors, and move the flaps as needed for a safe approach and landing. This combination ensures the aircraft can be configured for landing even with multiple system failures.

That’s why the components listed—landing gear, main gear inboard doors, and flaps—fit the emergency system’s responsibilities. Other functions like speed brakes or nose gear doors aren’t part of this backup circuit in many configurations, so they aren’t included here.