26-07-2012, 12:16 PM
PNEUMATIC SYSTEMS
Pneumatics.pdf (Size: 3.97 MB / Downloads: 300)
Aircraft Pneumatic Systems
Aircraft Pneumatic Systems power Instruments, landing gear, flaps, air conditioning, windows, doors and more
Aircraft Pneumatic Systems
•Sometimes called vacuum pressure systems
•Similar to hydraulic system but with air instead of fluid
–Difference
•Air is compressible
•Fluid is notcompressible
•In light Aircraft, Suction Pressure Gauge shows Vacuum System Pressure
Components:
Advantages of Pneumatics
•Simple
•Reliable
•Light weight
•Safe
–(if properly maintained)
Pneumatics Use in Small Aircraft
Pneumatic systems in GA aircraft are pretty straightforward:
• Air Pump
• Vacuum Regulator
• Inlet Air Filter
• Overboard Vent Line
• Gauges:
– Attitude Indicator
– Heading Indicator
• System Indicators
– Suction Gauge
– Gyro Flag
– Annunciator Lights (AL)
• Not all aircraft have ALs
How Pneumatic Systems Works
•Filtered Air is pulled through system by vacuum pump
•Evacuated air passes through instrument case causes gyro to spin
•Spinning gyros provide “rigidity in space” for instrument references
•Air exhausts through Gyro Pressure Gauge exhaust port
–Gauge measures system pressure
•Failure Warning Systems
Pneumatic Air Filter
•Prevent system contamination
•Remove air particulates
•Clean air is essential to good operation
Pneumatic Pressure Regulator
•Prevents system over pressurization
•Insures proper calibration
Air Pump
Heart of pneumatic system is pressure or vacuum air pump(Usually engine driven)
•Two basic types :
•Wet air pumpsuse engine oil to lubricate pump internally
•Dry air pumps-more common –have graphite vanes inside pump casing -self-lubricate as pump rotates