Pneumatics Flashcards
What are the three sources of air on the ground?
External, APU and engine air
What’s another name for 5th and 8th stage air?
Mid and high stage
What’s the purpose of the pressure regulating shutoff valve?
Maintain a maximum bleed manifold pressure of approximately 40 psi
What’s the preferred source of air and why?
5th stage because it has a lower pressure and temperature
What’s the purpose of the 8th stage bleed valve?
To supply supplemental air to maintain bleed manifold pressure of 14 to 35 psi depending on configuration and existing conditions
What’s the caution associated with use of external air?
Do not connect air with electrical power off
What are the requirements for the APU load control valve to open in-flight?
Both engine bleed air switches, both pack switches, and both wing anti-ice switches must be in the OFF position
What’s the purpose of the isolation valve?
In the normally closed position, it isolates the left and right bleed air manifolds
Other than using the ISOLATION valve switch, how else can the isolation valve be opened?
APU air switch with weight on wheels, or engine MASTER START or CRANK
If the isolation valve cannot be opened electrically, how else can it be opened?
It incorporates a manual wrenching device
Why does one pack shut down after selection of MASTER START or CRANK, and another shut down with selection of L or R ENG START?
This shutdown is designed to prevent large pressure bump during start by initiating two smaller ones that shouldn’t be as noticeable
What’s the caution associated with use of engine bleed air and APU air?
They shouldn’t be selected ON at the same time
What computers control operation of the bleed air system?
Bleed Air Controllers (BAC’s)
What are BAC’s responsible for?
Regulation of bleed air manifold temperature and supply pressure (i.e. responsible for min pressures and all temperatures)
What wing temperature is maintained during wing anti-ice operation?
Approximately 130°F
