Flashcards in Air Systems, Anti-Ice and Rain Deck (22):
Positions and Function of CKPT/CABIN TEMP Selector Switches:
AUTO and MANUAL
• AUTO - Temperature automatically adjusts toward HOT or COLD when selector is moved left or right of index mark.
• MANUAL (COLD/STOP/HOT)
- Spring loaded to stop.
- Momentarily moving selector to HOT or COLD opens or closes temp. control valve.
- Displayed on L/R VALVE TEMP CONTROL indicator.
Blue AUTO 1 INOP and AUTO 2 INOP lights on the pressurization panel:
• INOP (2) (blue) - Illuminates when that system fails. Stby system automatically controls pressurization.
Meaning of amber AUTO INOP light on pressurization panel:
AUTO INOP (amber) - Both automatic systems failed. Pressurization is manually monitored and controlled.
FLOW Light (amber)
- Closed outflow valve
- Cabin climb rate is detected
Function of the air conditioning shutoff switch:
• OVRD - Deactivates auto shutdown of a/c packs.
• AUTO - Automatically shuts down packs if either engine fails during takeoff (cabin differential pressure of less than 1.3 psid.)
NOTE: Excessive thrust during one engine taxi may activate this automatic shutdown circuit and shut off both packs. Subsequent thrust reduction will restart the packs.
Function of the L/R pneumatic X-FEED valve levers (Open):
OPEN - Opens respective X-FEED valve.
Ground: Supplies APU bleed air or air from pneumatic ground source for operation of one or both a/c packs and for engine start.
In flight: Supplies bleed air requirements for airfoil ice protection.
Function of the L/R pneumatic X-FEED valve levers (Closed):
CLOSED - Closes respective X-FEED valve.
Ground: Shuts off APU bleed air or air from a pneumatic ground source used for operation of one or both a/c packs, or for engine start.
- Shuts off bleed air supply for airfoil ice protection system and for opposite engine pneumatic starts.
- A/C Pack pneumatic supply is from its respective engine only.
Function of the CABIN ALT Control Wheel:
• When cabin altitude control is selected to auto, control wheel rotates as cabin air outflow valve automatically adjusts to maintain cabin altitude.
• When cabin altitude control is selected to manual, control wheel is locked in position. To adjust cabin altitude, push down on the control wheel and rotate in the desired direction. Outflow Valve Position Indicator will indicate the position of cabin air outflow valve
Difference between the AUTO and HP BLD OFF positions of the air conditioning L/R SUPPLY Switches:
• AUTO – If low stage pneumatic supply pressure is too low, aug. valve opens to supply high stage bleed air
• HP BLD OFF - Closes augmentation valve inhibiting utilization of high stage bleed air
Operation of RADIO RACK Switch:
• VENTURI - Turns off radio rack fan. Opens venturi valve.
• FAN - Turns on primary radio rack fan and closes venturi valve to cool radio rack and heat forward cargo compartment. If primary fan fails in flight, standby radio rack fan automatically comes on.
NOTE: On the ground, both primary and standby radio rack fans are on, and the venturi valve is closed.
(88, 90) Function of TAIL De-Ice Pushbutton:
• Push - (Air foil system in-use) Closes shutoff valve to wing and opens the shutoff valve to tail to allow 2.5 minutes of tail de-ice. System automatically reverts to wing anti-ice function following the 2.5 minutes of tail de-ice function.
(88) How is air foil ice protection activated?
• AIR FOIL switch ON
- and -
• Crossfeed valve(s) OPEN
(88, 90) Effect of moving Ice Protection Panel METER SEL & HEAT select switch out of off position:
• Moving selector to any position except OFF energizes all heater circuits, except RAT(88)/TAT(90) probe while on the ground.
(90) Function of Ice FOD Alert system:
• Active only on the ground
• Alerts pilots to presence of wing upper surface ice caused by cold-soaked fuel or environmental icing.
• Overwing ice sensors, located near inboard aft corner of each main wing tank, detect ice buildup in these areas.
• L/R ICE FOD ALERT, when displayed on OAP, indicate presence of ice build-up on the wing upper surface.
• ICE FOD RESET/TEST switch (spring-loaded to center) located on overhead panel, tests and resets system.
(88,90) Function of WINDSHIELD ANTI-ICE switch:
- OFF - Deactivates windshield anti-ice system.
- ON - Provides electrical heat to outside of CA's, Center, and FO's windshields.
(88, 90) Describe the airfoil anti ice protection cycle:
• Air foil ice protection is only available in-flight.
• System activated by selecting AIR FOIL sw. to ON and placing crossfeed valve(s) to OPEN. Provides a continuous cycle of heat
- Wing leading edges (slats) and forward strakes for fifteen minutes, followed by
- 2 1/2 minutes of heat to horizontal stabilizer.
- Ram air inlet is heated during both cycles.
• Automatic cycle can be overridden by TAIL button which, when pushed, provides for 2 1/2 minutes of horizontal stabilizer de-icing, after which a new wing cycle starts.
(88) Positions and function of OVERWING HEATER Switch:
- Provides electrical power to wing heater control units when the airplane is on the ground.
- Switch normally guarded to ARM
OFF - Removes electrical power from heater control units.
(88) Function of Overwing Heater system:
• Prevents buildup of ice (from condensation cooled by super cooled fuel) on inboard corner of upper wing.
• Neither de-ices entire wing nor provides anti-ice or de-ice capability for environmental icing conditions.
How does engine anti ice function? What are indications on OAP when engine anti-ice is in use (MD-88)?
• When selected ON, amber (L/R) ENGINE VALVE message will appear on OAP indicating valves are in transit and disagree w/ switch position.
• When at least 1 valve is fully open, blue (L/R) ENGINE ANTI-ICE ON light on OAP illuminates.
• When all 3 valves are fully open, amber message extinguishes and blue light remains illuminated indicating normal system operation.
How does engine anti ice function? What are indications on OAP when engine anti-ice is in use (MD-90)?
When selected ON, engine ignition is activated and 7th stage valve opens providing air for engine anti-icing to cowl only.
- Electrical heat for fuselage strakes is activated.
- Amber (L/R) ENGINE VALVE msg appears on OAP, indicating that engine anti-ice valve position disagrees w/ ENG anti-ice switch position.
- Blue (L/R) ENG ANTI-ICE ON indicates engine nose cowl and fuselage strake anti-ice selected.
NOTE: On MD-90, rubber coated tip is mounted slightly off-center to prevent ice buildup on spinner.
(88, 90) What conditions require use of engine anti-ice while on the ground?
• Ground: Must be on after start when ambient temp ≤6°C(42°F) w/ any of the following conditions
- Visible moisture is present. (Visible moisture may be fog, rain or snow. Fog is considered visible moisture when it limits visibility to 1 mile or less.)
- A 3° or less temp/dewpoint spread exists.
- Runways and taxiways are wet