4.3 Pneumatic Systems Flashcards
From where is the Pressurized air supplied?
Engine Bleed Air
- from intermediate pressure stage of the engine compressor / high pressure stage of the compressor
Auxiliary Power unit bleed air supply
- can be used for a pneumatic engine start
Ground Air
- APU or ground source would supply the pneumatic system prior to engine start
What pneumatic system loads are there?
Air conditioning and pressurization
Wing and engine anti ice
Engine start
Thrust reverser actuating
Hydraulic reservoir pressurization
Air driven hydraulic pumps ADP
Active flow control AFC
What types of Valves are there?
Pressure Regulating Shut-off Valve (PRSOV)
- controls bleed air by varying the discrete positions of the butterfly disk and shuts of the bleed air supply if needed
Shut off Valve (SOV)
- shuts of supply bleed air to dedicated pneumatic systems
Check Valve or Non-Return Valve (NRV)
- used for reverse flow protection, to keep up the system pressure and prevent backflow
What are the main functions of the APU?
On ground:
- independent from ground power supply
- apu bleed air is used for pneumatically starting of the main engines
- electrical power is generated by one or two generators driven by the load gearbox
In flight
- pressurized air for environmental control system (ECS) packs and engine restarting
- electrical power supply has priority over pressurized air supply
- unloading of main engine as power source
What are all-engine out causes?
fuel exhaustion
fuel contamination
volcanic ash damage
multiple bird strikes
human error
What are the main functions of the Ram Air turbine?
heart of an aircrafts emergency power system
deploys from the aircrafst wing or fuselage and rotates to generate sufficien power from the airsteam to control and land the aircraft
provides the aircraft with:
- hydraulic power for powered actuation or flight control surfaceses
- Electrical power for flight control computers, essential instruments, radio, cockpit lighting, windshield and pitot tube de-icing
