Part 8 Air Systems

  1. What systems are powered by the air system?
    Air conditioning packs, pressurization, airfoil anti-ice, cargo heating/ventilation, cargo loading, and potable water system.
  2. What is the status of air system when the "SELECT" and "MANUAL" lights are both illuminated in the air system SELECT switch?
    • 1. The air is in the manual mode but the switch is not in manual.
    • 2. Both automatic controllers have failed.
  3. What happens when the air system SELECT MANUAL switch is cycle to MANUAL and then back to AUTO?
    Environmental System Controller switches to the other channel.
  4. What does the BLEED AIR "PRESS" light indicate when illuminated?
    Bleed air pressure is low.
  5. What is the function of the BLEED AIR "PRESS" and BLEED AIR "MANF" / "TEMP HIGH" switches?
    Either switch can be used to open or close the associated bleed air valve when the Air Systems is in the manual mode. (Switches have no effect when the system is in auto mode).
  6. How is a failed bleed air manifold depicted on the AIR synoptic page?
    The affected manifold lines are displayed in RED.
  7. What does the BLEED AIR "TEMP HI" indicate when illuminated?
    The bleed air temperature is excessively High Downstream of the precooler. In the automatic mode the bleed air valve will close and the manifold will be re-pressurize from an alternate source.
  8. What happens to the air system when a MANIFOLD FAIL "MANF" light illuminates?
    The automatic controller will shut down the failed manifold by closing the bleed air valve and isolation valve(s).
  9. What is the function of the isolation shut off valves (ISOL 1-2 and ISOL 1-3)?
    To allow air from one system to another when needed if less than three engine bleed sources are operable. The isolation valves may be opened to supply air pressure to components of the inoperative system.
  10. What does an isolation valve "DISAG" light indicate?
    Valve position disagrees with commanded position; or if in the MANUAL mode, valve is in transit. Light is inhibited for 10 seconds in the AUTO mode.
  11. With the Apu operating, what happens to the isolation valves when the APU switch is placed "ON"?
    If the air is in AUTO both isolation valves will open automatically. If the air system is MANUAL, the isolation valves must be opened manually.
  12. During engine start, when will the packs automatically shut down?
    The packs will shut down when an ignition system is selected (for 2 minutes).
  13. Explain the function of the ECON switch?
    • ON = Packs in low flow
    • OFF = Packs in normal flow
  14. How many packs can be supplied by one engine?
    One engine can be used to supply air to a maximum of two packs, or one pack and both wings anti-ice.
  15. What is the default configuration of the packs for takeoff?
    Packs Off.
  16. When will the bleeds and packs turn on during a packs off take off?
    At climb thrust above 1500 AFE or 4500 AFE if climb thrust is not selected.
  17. When is the manifold fail detection system automatically tested?
    When the annunciator light test is performed. (Button held for more than 10 seconds when the aircraft is on the ground). Light test in flight has no effect on manifold control system.
  18. Which air conditioning system provides trim air?
    Systems # 1 and # 3.
  19. Describe what happens to the air system during a normal engine start, commencing with # 3, # 1 then # 2.
    During engine start, the packs are shut off when ignition is selected. The 1-3 isolation valve will close after engine # 3 starts and #3 pack is turned on. After #1 engine starts, the 1-2 isolation valve closes and the # 1 pack is turned on. After #2 engine is started the APU bleed valve must be closed before the #2 pack will be turned on.
  20. When does the cabin altitude light illuminate?
    Approximately 10000 ft.
  21. What is the function of the NO MASK switch and light?
    The light illuminates when cabin altitude exceeds about 15,000 ft, and any/all masks have not deployed. The switch is also used as an alternate method of deploying the masks.
  22. What is the function of the PACK switches?
    Controls the respective pack flow control valves when the air system is in the MANUAL mode. (Switches have no effect when the system is in the AUTO mode.)
  23. What does the PACK "FLOW" light indicate, when illuminated?
    The FLOW light indicates an insufficient flow when the pack is commanded ON, or airflow is present when the pack is commanded OFF.
  24. External air can supply which pneumatic systems?
    # 1 and # 2. Connect to duct # 1 if a large air cart is used used. Connect to duct # 1 and # 2 if two small carts are used.
  25. How is the APU air removed after engine start?
    Place the APU air switch to OFF.
  26. What does the USE ENGINE AIR portion of the APU Air switch indicate when illuminated?
    APU Air is ON and the pressure differential is greater than 1.5 PSI
  27. When is the # 2 pack turned on during engine start?
    After the flight crew closes the APU isolation valve.
  28. What does the "AVNCS OVHT" light indicate when illuminated?
    An overheat condition is sensed in the avionics compartment.
  29. What happens to the air system when "AVIONICS OVERHEAT" condition exists?
    The trim air system is automatically turned OFF.
  30. What are the conditions that will cause the "FLOW" light in the AVNCS switch to illuminate?
    • A. Cooling air through the avionics or center accessory compartment is below normal.
    • B. Cabin inflow is insufficient for pressurization.
    • C. Cabin altitude is greater than 10,000 feet.
  31. What is the function of the OVRD mode of the AVNCS FAN switch?
    Closes the Venturi shutoff valve and turns ON the avionics exhaust fan.
  32. What is the function of the CABIN PRESS SYSTEM SELECT switch?
    Push once selects manual control of the primary CPC. Push twice activates the back up automatic controller.
  33. Which areas of the MD-11 are pressurized?
    Flight Deck, main and lower deck cargo compartments, center accessory compartment, and the avionics compartment.
  34. What is the normal maximum scheduled cabin differential pressure?
    8.6 psid
  35. What is the maximum cabin differential pressure?
    9.1 psid
  36. What is the maximum cabin differential pressure during takeoff and Landing?
    0.5 psid
  37. What is the maximum cabin rate of climb or descent commanded by the pressurization controller when in the auto mode?
    750 fpm climb and 350 fpm to descent.
  38. How many controller modes are there for the pressurization system?
    Two identical AUTO modes and one electric MANUAL mode.
  39. Where is the pressurization outflow valve position indication displayed for takeoff?
    On the AIR synoptic page and on the pressurization panel.
  40. When is aircraft pre-pressurized in preparation for takeoff?
    When the slats are extended.
  41. How is the aircraft protected from excessive differential pressure?
    By three positive pressure relief valves.
  42. What does the "SELECT/MANUAL" light on the pressurization control panel indicate, when illuminated?
    Automatic control and the system has switched to manual. The switch must be pressed to disconnect the automatic drive circuits.
  43. Explain the function of the ditching switch?
    When the ditching switch is pressed:

    • A. Inhibits the GPWS.
    • B. Maintains existing cabin pressure differential.
    • C. Packs shut off at 2500 feet RA or cabin differential pressure is less than 0.5 psid whichever occurs first.
    • D. Closes Venturi shut off valve, ram air door (if open) and closes the outflow valve.
  44. How is the landing field elevation derived when the pressurization system is operated in the automatic mode?
    Automatically derived from the FMS database when destination airport is entered.
  45. How is the landing field elevation derived when the FMS data is not available?
    Set manually by the pilot by rotating the CABIN PRESS MANUAL LDG ALT knob more than 120 degrees (pressurization system must be in AUTO) and setting the landing field elevation on the AIR synoptic Page.
  46. Which air systems are normally used for airfoil anti-ice?
    • Air system 1, left wing
    • Air system 2, tail
    • Air system 3, right wing
  47. Which synoptic page is used to verify the position of the airfoil anti-ice valves?
    The Air synoptic Page.
  48. For how long must the "NO MASK" switch be held for the oxygen mask to be deployed?
    3 to 5 Seconds.
Card Set
Part 8 Air Systems
MD11 Air Systems