Pneumatics questions and answers
graded A+ updated
Subsystems of pneumatic system - correct answer ✔✔Bleed air, air conditioning, pressurization,
supplementary cooling, auxiliary heat systems
Which subsystem supplies airflow required to operate the various other systems, including AC &
PX systems? - correct answer ✔✔Bleed air system (from either engines or ground cart)
Where does the engine bleed air system supply the pre cooled & px-regulated air? - correct
answer ✔✔To the wing manifold
AC provides required conditioned air for... (2 things) - correct answer ✔✔1. Crew comfort 2.
Equipment cooling
How does the px system maintains airplane px? - correct answer ✔✔Regulating the rate at
which the AC air is discharged overboard
Which stage of high pressure compressor (N2) is the primary air source? - correct answer
✔✔5th stage
When does the other stage (not primary one) open? Which stage is this? - correct answer
✔✔When 5th stage px is low (typically below 50% N1), the 9th stage bleed valve opens to
supply air
Bleed air flow structure from engine bleed air to wing manifold - correct answer ✔✔5th/9th
stage >> check valve >> bleed air regulating valve >> precooler (cooled by fan discharge) >>
bleed air shutoff valve >> wing manifold
, What does the bleed air px regulating valve do? - correct answer ✔✔Controls the px of air
entering the pre cooler
Are the bleed air px regulating valve mechanically or pneumatically operated? Do they have
external controls? - correct answer ✔✔Pneumatically operated. No external controls
What do the bleed air px regulating valve do when engine is shutdown? What about the 9th
stage valve & 5th stage check valve? - correct answer ✔✔Regulating valve - Open when engine
shutdown; stage valves - close
How is the bleed air px regulating valve controlled? - correct answer ✔✔Controlled by bleed air
flow modulator. Measures the px drop across the precooler. Goal is to regulate the bleed air
load so they are equal across all engines
What regulates the amount of fan discharge air used for cooling? - correct answer ✔✔Pre
cooler control valve
If the precooler control valve fails, what position does it go to? - correct answer ✔✔Full open
What does the bleed air shutoff valve do? - correct answer ✔✔Protects the wing manifold from
overtemp or over pressure (depending on how it was closed either automatically or manually)
How can the bleed air shutoff valve be closed? - correct answer ✔✔Pneumatically or manually.
Pneumatically: if there's an overpx
Manually: if bleed valve is pushed closed on OH panel or via fire switch pulled
If px is lost, does the valve opens or close automatically? - correct answer ✔✔Opens
graded A+ updated
Subsystems of pneumatic system - correct answer ✔✔Bleed air, air conditioning, pressurization,
supplementary cooling, auxiliary heat systems
Which subsystem supplies airflow required to operate the various other systems, including AC &
PX systems? - correct answer ✔✔Bleed air system (from either engines or ground cart)
Where does the engine bleed air system supply the pre cooled & px-regulated air? - correct
answer ✔✔To the wing manifold
AC provides required conditioned air for... (2 things) - correct answer ✔✔1. Crew comfort 2.
Equipment cooling
How does the px system maintains airplane px? - correct answer ✔✔Regulating the rate at
which the AC air is discharged overboard
Which stage of high pressure compressor (N2) is the primary air source? - correct answer
✔✔5th stage
When does the other stage (not primary one) open? Which stage is this? - correct answer
✔✔When 5th stage px is low (typically below 50% N1), the 9th stage bleed valve opens to
supply air
Bleed air flow structure from engine bleed air to wing manifold - correct answer ✔✔5th/9th
stage >> check valve >> bleed air regulating valve >> precooler (cooled by fan discharge) >>
bleed air shutoff valve >> wing manifold
, What does the bleed air px regulating valve do? - correct answer ✔✔Controls the px of air
entering the pre cooler
Are the bleed air px regulating valve mechanically or pneumatically operated? Do they have
external controls? - correct answer ✔✔Pneumatically operated. No external controls
What do the bleed air px regulating valve do when engine is shutdown? What about the 9th
stage valve & 5th stage check valve? - correct answer ✔✔Regulating valve - Open when engine
shutdown; stage valves - close
How is the bleed air px regulating valve controlled? - correct answer ✔✔Controlled by bleed air
flow modulator. Measures the px drop across the precooler. Goal is to regulate the bleed air
load so they are equal across all engines
What regulates the amount of fan discharge air used for cooling? - correct answer ✔✔Pre
cooler control valve
If the precooler control valve fails, what position does it go to? - correct answer ✔✔Full open
What does the bleed air shutoff valve do? - correct answer ✔✔Protects the wing manifold from
overtemp or over pressure (depending on how it was closed either automatically or manually)
How can the bleed air shutoff valve be closed? - correct answer ✔✔Pneumatically or manually.
Pneumatically: if there's an overpx
Manually: if bleed valve is pushed closed on OH panel or via fire switch pulled
If px is lost, does the valve opens or close automatically? - correct answer ✔✔Opens
