11.16 PNEUMATIC AND VACUUM👌🏼 Flashcards
Pneumatic systems are used as power sources for aircraft systems with high or low pressure
High
What are the power sources for pneumatic systems
- Engines
- APU
- GPU
What are the 4 basic categories for a pneumatic/vacuum systems
- vacuum
- Low p
- Medium P
- High p
Explain a low pressure pneumatic system
- supply of warm low p air (approx 1-10psi)
- e.g. for anti-icing (LE of wing or THS)
Explain a medium pressure pneumatic system
- typically 50-150psi and draws air from compressor section of turbine engine
Engine bleed air is used to pressurise the reservoirs of hydraulic systems (T or F)
True
Explain a high pressure pneumatic system
- stored in metal bottles at pressures between 1000-3000 psi
- usually 2 valves —> one is a charging valve
Explain the cross bleed system
- allows transfer of air through crossover ducts and cross bleed valves
Pneumatic duct is divided into 3 parts
- left wing pneumatic duct
- right wing pneumatic duct
- crossover duct
What should you do before working on any pressurised systems
- depressurise system fully
How does engine bleed air function
- turbine engines have pressurisation systems, where pressurised air is taken from compressor section (low or high)
When is Low pressure bleed port used in a engine
- take off
- climb
- cruise
When is High pressure bleed port used
- when LP air supply is inadequate
- usually during low speed flight, descent, low engine power
Bleed air is available when APU is running above ——%
95%
Where is the ground air supply supplied to
- pneumatic manifold
How can you de-energise pneumatic manifold
- supply cart powered down and remove hose
High pressure systems is typically in a range of
1000 - 3000 psi
What are the 2 main types of vacuum pumps
- wet type
- dry type
Explain wet type
- made from steel
- lubricated from engine low pressure oil system
Explain dry pumps
- self lubricating using air (no need for oil)
- pump element made by carbon
Explain pressure relief valves
- used in pneumatic systems to prevent damage
- prevents excessive pressure
- If air pressure becomes high, it opens to relieve excess pressure
Explain check valve
- air compresses light string, forcing check valve flap to open, allows air to exit outlet port
- one direction flow control valve
Explain restrictor valve
- reduces volume of airflow, airspeed delivered to the user system
Pneumatic systems can be controlled automatically and manually (T or F)
T
What temperature must the pneumatic system remain within
- between 160c - 200c
What does a leak in an air duct cause
- overheating
