Definition
The transmission and control of energy through a pressurized fluid — either liquid (hydraulics) or gas (pneumatics) — used to move components, apply force, or operate aircraft systems such as landing gear, brakes, flight controls, and flaps.
Plain English
Using pressurized liquid or gas to do work — like pushing, pulling, lifting, or holding parts of the aircraft in place.
Context Anchor
Seen in aircraft systems and maintenance discussions of hydraulic and pneumatic systems, especially brakes, landing gear, flaps, and flight controls.
Derivation
From Latin fluidus (flowing) and Old French poeir (to be able). The term captures the idea that a flowing substance under pressure can be made to do useful work.
Why Pilots Care
Most large-aircraft systems that move heavy components — gear, flaps, brakes — rely on fluid power. Understanding the term helps a technician or pilot recognize that hydraulics and pneumatics are two branches of the same underlying principle.
Intuition Check
Fluid power does not mean the fluid itself is the power source. It means pressure in the fluid carries force from one place to another.
Example Sentence 1
The aircraft's landing gear, brakes, and flaps all rely on fluid power to operate.
Example Sentence 2
Loss of fluid power in the landing gear required the crew to use the emergency extension handle.