737 Systems: Pneumatics Flashcards
What sources supply air to the Bleed Air System?
Engines, APU, or ground cart (LP or HP)
What causes the engine bleed valve to automatically close? Which lights indicate this has occurred?
High Temperature or High Pressure
Will cause the BLEED TRIP OFF light, AIR COND annunciator, and MASTER CAUTION to illuminate
Which conditions will the TRIP RESET switch reset?
The BLEED TRIP OFF, ZONE TEMP, or PACK lights, if the exceedances no longer exist
What will cause the automatic closure of the APU Bleed valve?
When the APU is shut down regardless of switch position
Normally, what is the position of the Isolation Valve with the Isolation Valve switch in AUTO?
Closed
What will cause the Isolation Valve to open automatically with the Isolation Valve switch in AUTO?
Placing the Engine BLEED Air or AC PACK switches to OFF
What does a DUAL BLEED light indicate?
When the APU Bleed Air Valve is OPEN and:
-ENG 1 Bleed Switch ON
And/or
-ENG 2 Bleed Switch ON with the Isolation Valve OPEN
What is the primary source of conditioned air in the Flight Deck?
Left PACK
A single PACK in High Flow mode can maintain pressurization up to what altitude?
Up to the Maximum Certified Ceiling
What conditions would cause a PACK to change from Normal to High Flow with both PACK switches in AUTO?
If Airborne, with Flaps UP, both PACK switches in AUTO, and ENG Bleed Switches to ON, if on PACK fails, an engine fails, or a PACK switch selected OFF, the remaining PACK switches to high air flow.
What is indicated by the amber PACK light on the Bleed Air Panel?
Indicates a failure of the primary and standby pack controls for the same pack.
What provides cooling air for the heat exchangers in the PACK system?
Ram Air
What is indicated by a bright blue RAM DOOR FULL OPEN light?
Whenever a Ram Air Door is fully open
What is the purpose of the recirculating fans?
To reduce:
-Bleed Air Load (efficiency)
-Engine Bleed Air (increase relative humidity)
-Airborne participles and micro-organisms (higher circulation in HEPA filters)
What does the illumination of the ZONE TEMP light indicate?
An associated overheat of the supply duct and the closing of that associated Trim Air Valve
(CONT included a failure of BOTH the primary and standby temperature controls)
What limitations, if any, are there when using external conditioned air?
PACK switches should be positioned off
What is the purpose of the Equipment Cooling System?
To cool the electronic equipment in the Flight Deck and the E/E Bay
Which, if any, of the Cargo Compartments are heated by the Equipment Cooling System exhaust fans?
The FWD Bay
What does the Equip Cooling OFF light indicate?
Loss of airflow due to the failure of the respective Equipment Cooling Fan
How is the alternate Cabin Pressurization Controller selected?
By positioning the Pressurization Mode Selector to ALTN
What are the indications that an active Cabin Pressurization Controller has failed?
AUTO FAIL amber light and ALTN green light. Ascended of the ALTN light indicates a DUAL Cabin Pressure controller failure
What causes the illumination of the OFF SCHED DESCENT light?
If the aircraft appears to descend without having reached the present cruise altitude selected in the FLT ALT window
At approximately what altitude will the CABIN ALTITUDE light and the Cabin Altitude Warning Horn activate? Can the horn be silenced?
Either Cabin Altitude Pressure switches sense the Cabin. Altitude exceeds 10,000ft +/- 1000ft
Yes you can silence it with the ALT HORN CUTOUT button on the Cabin Altitude Panel
