Definition
Aircraft systems that use pressurized air, typically bled from the engine compressor, to power or operate components such as deicing boots, pressurization, air conditioning, engine starting, and certain instruments or controls.
Plain English
Systems on the airplane that run on pressurized air. The engine pulls in and compresses air, and some of that compressed air is sent through ducts to operate other equipment around the aircraft.
Context Anchor
Seen in turboprop engine discussions when the handbook describes the systems driven or supplied by the engine.
Derivation
From the Greek 'pneuma,' meaning breath or air. A pneumatic system is, quite literally, an air-powered system — useful to remember because it distinguishes these systems from hydraulic (fluid-powered) and electrical systems.
Why Pilots Care
These systems enable reliable engine starting and accessory functions; loss of pneumatic pressure can affect engine operation and safety margins.
Intuition Check
Do not think of pneumatic only as something involving tires. In aircraft systems, pneumatic means air pressure is being used to operate equipment.
Example Sentence 1
After engine start, the pilot confirmed the pneumatic systems were supplying air to the deicing boots and cabin pressurization.
Example Sentence 2
The preflight checklist includes verifying that all pneumatic systems are pressurized and leak-free before flight.