Pneumatics Flashcards
What are the three sources of air on
the ground?
External, APU and engine air
What’s another name for 4th and 8th
stage air?
Mid and high stage
What’s the purpose of pressure
regulating shutoff valve?
Regulates bleed manifold pressure to
44 +/- 8 psi. Under normal conditions,
bleed manifold pressure shouldn’t exceed
52 psi.
What’s the preferred source of air and why?
4th stage because it has lower pressure and
temperature
What’s the purpose of 8th stage bleed valve?
To supply supplemental air to maintain
minimum bleed manifold pressure
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’s the purpose of the isolation
valve?
Isolate left and right bleed air manifolds
Other than using ISOLATION valve
switch, how else can isolation valve
be opened?
Selection of APU BLEED AIR switch
with weight on wheels, or selection of
ENGINE START or Crank switches
If the isolation valve cannot be opened
electrically, how else can it be
opened?
It incorporates manual wrenching device
What computers control operation of
the bleed air system?
Bleed Air Controllers (BAC’s)
What are BACs responsible for?
Regulation of bleed air manifold
temperature and supply pressure (i.e.,
responsible for min pressures and all
temperatures)
What happens to high stage bleed
pressure when a PACK switch is
selected to OFF?
It resets to 22 or 34 psi depending on
altitude
What temperature would you expect
at precooler inlet during wing anti-ice
operation?
Maximum of 700°F depending on power
lever position
What precooler outlet temperature
would you expect under normal
operating conditions?
400°F
What’s the maximum temperature of
bleed air at the precooler outlet during
wing anti-ice operation with single
ENG BLEED switch selected to ON?
500°F
