Under which conditions does the System B engine-driven pump operate to supply hydraulic fluid for the landing gear transfer unit?

• A. The aircraft is on the ground, landing gear lever is positioned down, no. 1 engine RPM is above limit value
• B. The aircraft is airborne, landing gear lever is positioned UP, either main landing gear is not up and locked, and no. 1 engine RPM drops below a limit value
• C. The aircraft is airborne, landing gear lever is positioned UP, main landing gear is up and locked, and no. 1 engine RPM is above limit value
• D. The aircraft is on the ground, landing gear lever is positioned UP, either main landing gear is not up and locked, and no. 1 engine RPM is below limit value

Answer: (B)

The correct choice indicates that the System B engine-driven pump operates under specific conditions that ensure the hydraulic fluid is available for the landing gear transfer unit when the aircraft is airborne. In this scenario, the landing gear lever is positioned UP, which is crucial because it typically indicates that the pilot has raised the landing gear and is in the process of retracting it after takeoff.

Furthermore, the pump's operation is dependent on the condition that either of the main landing gears is not up and locked. This situation requires hydraulic fluid to help secure the landing gear properly, ensuring safety during flight. Lastly, the stipulation regarding the number one engine's RPM dropping below a limit value signals that the system is prepared to activate to provide backup hydraulic pressure when normal operation parameters are not met.

Overall, these conditions align with operational safety protocols that dictate when additional hydraulic system support may be necessary to facilitate landing gear management during flight, especially if there is a potential issue with gear locking.