If the hydraulic system pressure increases above 4200 psi, what is the recommended action?

The recommendation to depressurize all PRI, SEC, and AUX hydraulic pumps when the system pressure exceeds 4200 psi is based on safety and equipment protection considerations. Operating at pressures above specified limits can lead to system failures or damage to hydraulic components. Depressurizing all pumps simultaneously helps to quickly normalize the pressure across the hydraulic system and prevents potential risks associated with high pressure, such as leaks or ruptures.

This action is vital to maintain operational integrity and ensure that the hydraulic system functions within its designed pressure range. It is essential for the safety of the aircraft and its systems, allowing for a swift recovery from an overpressure situation. The decision to address all hydraulic pumps collectively reflects best practices in aviation maintenance and safety protocols, prioritizing the overall health of the hydraulic system.