1/18/23 Air Systems Flashcards
What sources supply air to the Bleed Air System?
- The engines
- Auxiliary Power Unit (APU)
- (on the ground) an external pneumatic air cart/source.
What causes the engine bleed valve to automatically close? Which light(s) indicate this has occurred?
Excessively high bleed air temp
Excessively high bleed air pressure
The Bleed Trip OFF when illuminated, indicates that Bleed Trip Sensors have automatically closed the Engine Bleed Air Valve with excessively high engine bleed air temperatures (254°C) or excessively high pressures (220 psi). The illumination of the BLEED TRIP OFF light will cause the AIR COND annunciator, and MASTER CAUTION lights to illuminate.
Which conditions will the TRIP RESET switch reset?
Will reset the bleed trip, or zone temp, or pack lights condition if the exceedance(s) no longer exist.
What will cause the automatic closure of the APU Bleed Valve?
The valve closes automatically 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.
With the ISOLATION VALVE switch in AUTO, Engine BLEED Air and Air Conditioning PACK switch positions are used for positioning the Isolation Valve. In AUTO, the Isolation Valve will be closed when:
• both Engine BLEED Air Switches are ON, and
• both Air Conditioning PACK switches are in AUTO or HIGH
What will cause the Isolation Valve to open automatically with the Isolation Valve switch in AUTO?
Placing any one of the Engine Bleed or Air Conditioning Pack switches to OFF will automatically open the Isolation Valve.
- Isolation Valve position is not affected by the APU BLEED
What does a DUAL BLEED (amber) light indicate?
illuminates when the APU Bleed Air Valve is open,
and:
• Engine Number 1 Bleed Switch is positioned to ON, and/or
• Engine Number 2 Bleed Switch is positioned to ON with the Isolation Valve open
This configuration exposes the APU to engine bleed air back pressure should the APU Check
Valve fail.
(Looks only at ENG BLEED switch positions, Actual Isolation valve position and APU Bleed valve position)
What is the primary source of conditioned air in the Flight Deck?
A portion of conditioned air from the left pack.
A single pack in high flow mode can maintain pressurization up to what altitude?
41,000’ MSL
A single pack in high flow mode is capable of maintaining pressurization and acceptable temperatures throughout the aircraft up to the maximum certified ceiling.
What conditions would cause a pack to change to high air flow with both PACK switches in AUTO?
If one pack fails or one engine fails or a PACK switch is selected to OFF.
When the aircraft is airborne with flaps fully retracted (UP), both PACK Switches in
AUTO, and ENG Bleed Switches to ON, if one pack fails or one engine fails or a PACK switch is selected to OFF, the remaining pack automatically switches to high air flow to increase ventilation
What is indicated by the PACK (amber) light on the Bleed Air Panel?
- Primary and standby pack controls are failed.
- Pack overheat.
indicates failure of both the primary and standby pack controls for the same pack. The pack will continue to operate without control unless excessive temperatures cause the pack to trip off.
when illuminated, indicates an overheat condition exists
(provided by temp sensors located in the cooling cycle) and causes the Pack Valve to close (terminating the operation of the pack).
The illumination of the PACK light causes the AIR COND annunciator and MASTER CAUTION lights to illuminate.
What is indicated by a bright blue RAM DOOR FULL OPEN light?
Illuminates whenever a ram door is fully open.
- may remain illuminated for a short period of
time on the Takeoff Climb after flaps are retracted to UP during operations in extremely hot temperatures.
What is the purpose of the recirculation fans?
The Recirculation Fans increase air flow to the Passenger Cabin through the main distribution system.
What does the illumination of the ZONE TEMP (amber) lights indicate?
Indicates a supply duct overheat and the associated Trim Air Modulating Valve closes.
The illumination of the CONT CAB ZONE TEMP will cause the AIR COND annunciator and
MASTER CAUTION lights to illuminate.
What limitations, if any, are there when using external conditioned air?
PACK switches should be positioned to OFF
When using external conditioned air, the PACK switches should be positioned to OFF (air conditioning pack air pressure will reduce the efficiency of the external conditioned air cart).
Conditioned air temperature is controlled at the external conditioned air cart.
NOTE: Flight Deck air conditioning controls are ineffective to control and/or modify
external preconditioned air temperatures.
What is the purpose of the Equipment Cooling System?
Cools electronic equipment in the Flight Deck and the E/E bay
How is the Alternate Cabin Pressurization Controller selected?
Automatically when auto fail has occurred, and manually with the ALTN selected.
• ALTN –
- automatic pressurization control
- alternate mode of operation uses DC motor
- ALTN (green) light illuminated when ALTN selected with Pressurization Mode Selector or when auto fail has occurred (AUTO FAIL light is illuminated)
What are the indications that the active Cabin Pressurization Controller has failed?
The AUTO FAIL and ALTN lights will be illuminated
As a result of a single controller failure (Pressurization Mode Selector in AUTO), the ALTN light will illuminate with the illumination of the AUTO FAIL light indicating that the pressure control has automatically transferred to the other auto controller (ALTN mode).
Moving the Pressurization Mode Selector to the ALTN position extinguishes the AUTO FAIL light, however the ALTN light remains illuminated to indicate single channel operation.
What causes the illumination of the OFF SCHED DESCENT (amber) light?
If the aircraft begins to descend without having reached the preset cruise altitude
Example: a flight aborted in climb and returning to the departure airport. The AIR COND annunciator and MASTER CAUTION lights also illuminate
At approximately what altitude will the CABIN ALTITUDE (red) light and the Cabin Altitude Warning Horn activate? Can the horn be silenced?
10,000’ +/- 1000’ Cabin Altitude.
Yes, the horn can be silenced by pressing the ALT HORN CUTOUT switch.
The Cabin Altitude Warning Horn (intermittent horn) activates and the CABIN ALTITUDE warning lights illuminate when the cabin altitude exceeds 10,000 +/-1000 ft as sensed by either of the two Cabin Altitude Pressure Switches.
When the switch is pressed momentarily, the Cabin Altitude Warning Horn is silenced. However, the CABIN ALTITUDE warning lights will remain illuminated until the condition no longer exists.
WARNING! The Cabin Altitude and Takeoff Configuration warnings use the same aural tone (intermittent horn) when activated.
