What is system priming and why is it performed in ALRE maintenance?

• A. Priming fills the hydraulic system with fluid and purges air to ensure reliable operation.
• B. Priming calibrates sensors.
• C. Priming tests electrical circuits.
• D. Priming observes color of hydraulic fluid.

Answer: (A)

System priming means filling the hydraulic system with fluid and removing trapped air so the pump has a flooded, air-free suction path. In ALRE maintenance, this is essential because the launch and recovery gear depend on precise hydraulic actuation. Air in the lines can cause cavitation, erratic valve movement, delayed responses, a spongy or noisy feel, and uneven actuator performance, all of which can jeopardize aircraft launch or recovery and risk component damage. Priming ensures the pumps can develop proper suction, fully pressurize the lines, and keep actuators moving smoothly under load, especially after maintenance when air might have entered during draining or circuit openings. It also helps bleed air from accumulators and vents so the system remains ready for reliable operation. Calibrating sensors, testing electrical circuits, or merely checking fluid color are separate tasks and do not establish the ready-to-operate condition that priming provides.