United 737 Air Systems/Pneumatics/AC/Pressurization Flashcards
On the cabin pressurization panel, what has occured if both the Amber AUTO FAIL light and the green ALTN light is illuminated?
A single channel controller failure has occured
The OFF SCHED DESCENT light indicates the aircraft began descent before having reached the planned cruise altitude. What does the controller program the cabin to?
To land at the takeoff field elevation without further pilot inputs
Which stages of the compressor section is bleed air obtained from?
5th and 9th
The ___ high stage valve modulates open to maintain proper pressure when 5th low stage pressure is insufficient
9th
The engine bleed air valve is normally ______ operated and DC power activated
Pneumatically
What does the illumination of the BLEED TRIP OFF light idicate?
Engine bleed air temperature or pressure exceeds a predetermined limit
When the BLEED TRIP OFF light illuminates, what effect does this have on the engine bleed air system?
The respective engine bleed air valve closes automatically
The isolation valve is ____ when the isolation valve switch in AUTO, both engine bleed air switches ON, and both air conditioning pack switches AUTO or HIGH.
CLOSED
The isolation valve is ____ when the isolation valve switch is in AUTO, if either an engine bleed air switch or a pack switch is positioned OFF
OPEN
Turning the APU bleed air switch OFF with the PACK switches in AUTO will cause the isolation valve to open
FALSE
The APU bleed air valve is ____ operated and ___ activated
pneumatically; DC
Engine thrust must be ___ with the DUAL BLEED light illuminated
Limited to Idle
___ causes a WING BODY OVERHEAT condition.
A bleed air duct leak
Which WING BODY OVERHEAT light will illuminate if a leak in the bleed duct from the APU occurs?
LEFT
The isolation valve____ if either engine BLEED air or air condition PACK switch is positioned OFF with the ISOLATION VALVE switch in AUTO
Automatically Opens
Conditioned air from which PACK, upstream of the mix manifold, flows directly to the flight deck?
Left Pack
Air from the left pack, air from the right pack, and air from the recirculation system is combined within the ___
Mix Manifold
On the ground, the APU can supply air for ___for all operations
2 packs
With the Air Conditioning PACK switches in AUTO and both packs are operating
the packs provide “Normal air flow”
When one pack is operating, _____ with the air conditioning PACK switches in AUTO
the operating pack provides HIGH AIR FLOW!
Anyime the pack valve closes on the 737 700 the air mix valves are driven to the ____ position automatically
FULL COLD
In the automatic temperature mode on the 737 700 the _____ are operated by the automatic temperature controller
Air Mix Valves
The automatic temperature controller is bypassed when the temperature selector is positioned to ____ on the 737 700.
Manual
The ram air system is used to provide cooling for what part of the air conditioning systems?
Heat Exchangers
A DUCT OVERHEAT light causes the appropriate air mix valve to drive ______ on a 737 700
FULL COLD
When a PACK TRIP OFF light illuminates, the pack valve ______ on the 737 700.
Automatically closes and the mix valve drives full cold
In a 737 800 ___ if an amber ZONE TEMP light illuminates.
the MASTER CAUTION light will illuminate and the trim air valve closes
The recriculation fan system ____ the engine bleed air demand and air conditioning load
REDUCES
What does the TRIP RESET switch reset?
- DUCT OVERHEAT on the 737 700 or the ZONE TEMP on the 737 800
- BLEED TRIP OFF, PACK TRIP OFF
On the 737 800 what is indicated by the PACK light?
A pack trip off
or
Failure of both primary and standby pack controllers
Cabin air outflow controlled by
Outflow Valve and the Overboard Exhaust Valve
On the Cabin Pressurization Panel, what does an illuminated amber AUTO FAIL light indicate?
Automatic Pressurization system failure is detected
Manually positioning the outflow valve to OPEN will cause cabin altitude to ___
Climb
The main outflow valve is the overboard exhaust exit for the majority of the air circulated through the passenger cabin and is actuated by one of the ___ DC motors
THREE
On the cabin altitude panel, the ___ on the CABIN altimeter/ Differential Pressure indicator indicates the cabin altitude in feet
INNER SCALE
On the Cabin altitude panel, the ___ on the CABIN Altimeter/Differential Pressure indicator indicates the differential pressure between cabin and ambient PSI
OUTER SCALE
The intermittent cabin altitude warning horn can be cut out ___
by pushing the ALT HORN CUTOUT Switch
At _____ cabin altitude the intermittent cabin altitude warning will sound
10,000’
Cabin rate of climb displayed ____
on the cabin rate of climb indicator
On the Cabin Pressurization Panel, ____ & ____modes automatically pressurize the aircraft.
AUTO & ALTN
What precools engine bleed air?
A precooler, or heat exchanger
Does the APU bleed air switch affect the isolation valve position?
NO
Does the APU bleed air valve automatically close when the APU is shut down?
YES
The Wing Body Overheat Test Switch ____
All answers are correct
Conditioned air for the cabin comes from ____
Air from the Aircraft AC or a preconditioned ground source
With the air conditioning PACK switch in HIGH ____
The respective pack provides high air flow
In a 737 700- a PACK TRIP OFF is caused by
A pack temperature exceeding limits
What makes the equipment cooling OFF light illuminate?
Loss of air flow due to failure of an equipment cooling fan
The Pressurization Mode Selector in the MAN mode, the outflow valve switch takes approx. _____ second to move the outflow valve in the full range of motion.
20 seconds
T/F 737 700: The pack valve will close if the cooling cycle overheats and is associated with a PACK TRIP OFF light
True
