Where does APU bleed air enter the pneumatic manifold?
Left of the isolation valve.
Where does the external pneumatic air enter the pneumatic manifold?
Right of the isolation valve.
What are all the sources that provide air for the pneumatic system?
External, APU, 5th and 9th stage engine bleeds
An -800 has three air conditioning control zones. The temperature controllers are in NORMAL and trim air is ON. The two packs will supply air at what temperature?
A termperature for the zone requiring the most cooling.
What happens when an engine bleed switch is placed to ON?
If engine bleed air and electical power are available, the valve opens.
What does an illuminated engine BLEED TRIP OFF light indicate?
Excessive engine bleed air pressure or temperature advisory, engine bleed valve remains open.
How is engine bleed air temperature regulated?
Controlled engine fan air circulates through a precooler.
Air for starting the enines is supplied from_______.
The left or right pneumatic manifold.
TRUE or FALSE
The pneumatic manifold pressure sensors are DC powered; located in left & right pneumatic manifolds.
FALSE. The pneumatic manifold pressure sensors are AC powered.
What do the duct pressure pointers indicate when one pack valve switch is placed to OFF with the APU providing bleed air and the isolation valve in AUTO?
APU bleed pressure shows on both pointers. 4 corners switch with isol valve in auto.
What occurs when the APU bleed air switch is placed to on?
DC power signals valve to open, APU bleed air opens the valve if RPM is above 95%.
What is the power source for the pneumatic isolation valve?
AC power
Describe the isolation valve function.
Isolates left & right sides of the pneumatic manifold and is closed during normal operation.
What action causes the pneumatic isolation valve to open when the switch is in the AUTO position?
Placing an engine bleed air switch or pack switch to OFF.
What is the function of the DUAL BLEED light?
To warn when the APU may be back pressured by engine bleed air.
Which valve and switch combination causes the DUAL BLEED light to come on?
APU bleed valve OPEN & right engine bleed switch ON, with the isolation valve OPEN.
What is the crew action for an illuminated DUAL BLEED light prior to engine start?
No action. DUAL BLEED light is normal during engine start with APU bleed air.
Which condition illuminates a WING-BODY OVERHEAT light?
Bleed air leak in the APU bleed air duct.
Bleed air leak in the wing leading edge or inboard of the engine strut.
Bleed air leak in the aircraft keel beam.
What engine stages provide bleed air?
The 5th and 9th stage
TRUE or FALSE
The 9th stage engine bleed air is the primary source of bleed air for pneumatics when the engine is at cruise thrust.
FALSE. 5th stage.
The engine bleed valves are located:
Downstream of the 9th stage modulations/shutoff valve.
How are the bleed valves operated?
Electrically controlled and pneumatically operated.
Excessive engine bleed air pressure or temperature will cause what condition to occur?
A bleep trip
TRUE or FALSE
If the APU bleed valve and switch are open, the valve will automatically close with APU shutdown.
TRUE
TRUE or FALSE
A right WING-BODY OVERHEAT light could indicate a bleed air leak in the keel beam area.
FALSE
What -500 minimum duct pressure is required to operate two air conditioning packs from one bleed source?
20-25 PSI
The potable water system pressurization line connect to which part of the pneumatic manifold?
The left side
The Engine Bleed Valve Trip pressure sensor is located______.
Before bleed air reaches the engine bleed valve.
The Engine Bleed Valve Trip temperature sensor is located______.
After the engine bleed air passes the engine bleed valve and pre-cooler.
What limitation is imposed when the DUAL BLEED light is illuminated?
No more than idle engine power is allowed.
External pneumatic air can be used to start the number 1 engine______.
If the isolation valve is open.
The APU provides bleed air directly to______.
The left side of the pneumatic manifold.
TRUE or FALSE
The engine bleed valve must be open for ENGINE anti-ice to available.
FALSE
What is the normal source of conditioned air for the flight deck with both packs operating? (300/500)
The left pack prior to the mix manifold.
What is the indication on the respective AIR MIS VALVE position indicator when a pack valve closes? (300/500/700)
Full COLD
Describe the flow of bleed air through a pack.
Bleed air flows through a heat exchanger, the ACM compressor, a second heat exchanger, then the ACM turbine.
When are the RAM DOOR FULL OPEN lights extinguished?
In cruise with low pack temperature.
On the ground, what is the proper indication of the ram door position lights?
RAM DOOR FULL OPEN lights illuminated
What is the function of the turbofan in the ram air duct? (500)
Augments ram airflow when a pack is operating on the ground or inflight with the flaps no up.
What is the purpose of the air conditioning system deflector doors?
The doors extend on the ground to prevent FOD ingestion.
What is the purpose of the recirculation fan?
Reduce pack loads & engine bleed demand.
Where is filtered RECIRC FAN air discharged?
Into the mix manifold
What happens to remaining pack when a single pack is operating with switch in AUTO and the other OFF inflight?
Remaining pack goes to high flow inflight when the flaps are UP.
With RECIRC FAN switch in AUTO, and both pack switches in AUTO, what does the recir fan do? (500)
Recir fan shuts down when either pack switch is placed to HIGH.
What does an illuminated DUCT OVERHEAT light indicate?(500)
Duct has overheated and mix valve have driven to full COLD.
How is hot air removed from the circuit breaker panels and the E&E compartment equipment?
By either the main or alternate equipment cooling fans.
When does the flow control vlave close? (500)
When cabin pressure differential reaches .25 psid
What does an illuminated EQUIP COOLING OFF light indicate?
NO airflow from the respective equipment cooling fan.
How is the forward cargo compartment heated when cabin differential pressure is above 2.6 psi with the forward outflow valve closed? (500)
The recirc fan maintains airflow around the outside of the compartment.
Which systems are reset by means of the TRIP RESET switch? (500)
DUCT OVERHEAT, PACK TRIP OFF & BLEED TRIP OFF
How are the pack & isolation valve switches positioned for a BLEEDS-OFF takeoff?
Pack switches AUTO, isolation valve switch CLOSE
During a bleed ON takeoff, the air conditioning pack switches and the isolation valve switch are positioned:
The right pack in AUTO, the isolation valve in AUTO, and the left pack in AUTO
Inflight, when both air conditioning packs are operating and the RECIRC FAN is in AUTO, placing a pack switch to HIGH: (500)
Turns the RECIRC FAN off
Causes the pack to operate at a higher than normal rate of air flow
Causes the forward outflow valve to open
With both packs operating, if air conditioning smok appears in the cockpit and in the cabin, the most likely source is: (500)
The left air conditiong pack
With the RECIRC fan switch in AUTO, the fan______. (500)
Operates if one pack is turned OFF and the other is in AUTO.
E&E compartment cooling airfow is normally provided by the:
Recirulating fan
Overheat temperature sensors that will cause a pack trip are located in the (500)
ACM compressor discharge duct, turbine inlet duct, and supply duct.
When parked at the gate, external conditioned air temperature______ controlled by the pack.
Is not
Bleed air for the pack is______as it passes through the primary heat exchanger.
cooled
Each pack has a temperature selector. The selector on the left controls the temperature for: (500)
Flight Deck
With the pack switch turned OFF, the pack valve closes and the mix valves: (500)
Move to full cold.
With aircraft airborne, when is the forward outflow valve closed? (500)
When the recirculation fan is operating.
Which cabin pressure control modes utilize the outflow valve DC motor? (non-digital controller)
STBY & MAN
When should the equipment cooling flow control valve close? (500)
At 2.50 psid
Which model 737 has a TRIM AIR switch on the overhead panel?
-800 model
Which 737 model has a Forward Outflow Valve?
-500 model
What occurs when the FLT GND switch is placed to FLT with aircraft on the ground, packs ON, doors CLOSED, and engine bleed air available? (500)
The main outflow valve modulates as necessary to maintain the aircraft at 200 feet below departure fiel elevation.
If the aircraft climbs above the altitude set in the pressurization controller FLT ALT window, the cabin pressure will remain constant until what psid? (500)
7.90 psid
The -700 has pressure relief valves that limit the cabin differntial to what value?
9.1 psid
What altitude is set in the STANDBY CAN ALT indicator when operating in AUTO during the receiving aircraft check?
200 feet below landing field elevation
What altitude is set in the STANDBY CAB ALT indicator during receiving aircraft check when operating the flight with the STANDBY pressurization system? (auto inop)
Takeoff field elevation minus 200 feet
What procedure is preferred for MANUAL control of pressurization? (500)
Use the MANUAL-CLOSE/OPEN switch & MAN DC for slower operation of the outflow valve.
What does an illuminated OFF SCHED DESCENT light indicate?
Aircraft descending without having reached the selected cruise altitude.
What does an illuminated AUTO FAIL light and STANDBY light on the pressurization panel indicate? (500)
Auto control has failed and automatically switched to STANDBY mode.
Which condition illuminates the pressurization AUTO FAIL light? (500)
Cabin rate of change has exceeded +or- 1800 fpm
Which lights should come on when AC electrical power is lost to the AUTO pressure control system? (non-digital system) (500)
AUTO FAIL & STANDBY
TRUE or FALSE
The outflow valve position indicator operates in all pressurization modes with AC power available.
TRUE
What is the purpose of the pressurization flight/ground switch GND position? (500)
Drives main outflow valve full open on the ground.
What occurs if the FLT/GND switch is not selected to FLT for takeoff? (500)
The aircraft will pressurize after takeoff.
TRUE or FALSE
The pressurization controller controls the ram air system ram door and exhaust louvers.
FALSE
What is the maximum differential pressure allowed by the System Safety Pressure Relief Valves? (500)
A differential pressure of 8.65
If the aircraft pressurization system is operating in AUTO on the ground, moving the FLT/GND switch from GRD to FLT will cause the aircraft to: (500)
Pressurize to approximately 200 feet below field elevation.
The forward outflow valve is closed when: (500)
The RECIRC FAN is operating
When is the RAM DOOR FULL OPEN light illuminated?
On the ground, or in flight with the flaps extended.
Illumination of the amber pressurization OFF SCHED DESCENT light indicates what situation?
The airplane is descending prior to reaching the selected flight altitude.
What is the maximum allowable differential pressure for takeoff?
.125 psid
TRUE or FALSE
The air condioning packs may be operated in HIGH during a bleed on takeoff.
FALSE
With the aircraft at the maximum certified altitude and one pack operating, what is the lowest cabin altitude that can be maintained?
