Hydraulic System

Hydraulic System uses pressurized fluid (typically Skydrol or MIL-PRF-83282 at 3,000-5,000 PSI) to power critical aircraft systems including flight controls, landing gear extension/retraction, brakes, nose wheel steering, thrust reversers, and flaps/slats.

Large aircraft have multiple independent hydraulic systems (typically 3) for redundancy. If one system fails, the remaining systems can still operate essential functions. Most modern fly-by-wire aircraft also have electric backup for critical flight controls.