What is the primary purpose of the transfer pump?

The primary purpose of the transfer pump is indeed to assist in both landing gear retraction and cargo door/ramp closing. This pump is critical in maintaining the hydraulic system's effectiveness, enabling various essential operations within the aircraft's systems.

In the context of landing gear operation, the transfer pump helps provide the necessary hydraulic pressure to retract and extend the landing gear smoothly and reliably during takeoff and landing cycles. For the cargo door and ramp, it ensures that the hydraulic mechanisms function correctly, allowing for the seamless opening and closing of the cargo areas, essential for load operations.

The integration of these functions reflects the complex hydraulic system within the C-17, where multiple components rely on the transfer pump's ability to deliver adequate hydraulic pressure. By fulfilling these dual roles, the transfer pump plays an essential part in ensuring both safety and efficiency during flight operations.