MD-11 Flight Crew Operations Manual
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Ice and Rain Protection -
Description and Operation
Ice.10.3
Pushing the TAIL ANTI-ICE switch opens the horizontal stabilizer anti-ice valve.
ON illuminates on the TAIL ANTI-ICE switch when the horizontal stabilizer is
commanded open. DISAG illuminates on the TAIL ANTI-ICE switch when the
switch is OFF and flow is sensed, or when the switch is ON and flow is not sensed.
The TAIL A-ICE DISAG alert is displayed
On the ground, the TAIL A-ICE DISAG alert is displayed and the DISAG light
illuminates when an anti-ice valve is open, regardless of the switch position.
The ESC depressurizes pneumatic system 2 after 27 seconds if the anti-ice valve
disagree condition continues to exist, and anti-ice air flow exceeds normal flow
tolerances after duct pressurization and if a CAC manifold failure occurs. A tail
manifold fail signal is transmitted to the PSC, which sends a signal to the ESC for
annunciation and shutdown of pneumatic system 2.
The tail anti-ice shutoff valve fails closed if valve power fails.
Engine Cowl Anti-Ice System
The engine cowl anti-ice system uses hot engine bleed air (11th stage for GE
engines) incorporating a swirl system for cowl ice protection. Hot bleed air is
ducted to the nose lip, where it is discharged by a nozzle, producing a swirling
flow into the circumferential chamber (D-duct).
For engine 2 cowl anti-ice system, hot bleed air is ducted from the engine and
discharged into the D-duct. The hot air then enters into a double skin passage
through openings located in the inner skin. The anti-ice air is exhausted from the
double skin passage into the aft compartment and vented overboard.
Engine cowl anti-ice valves are open when the flight crew selects the respective
anti-ice system on. The engine cowl anti-ice valves are opened by pushing the
appropriate ENG 1/2/3 ANTI-ICE switch. The anti-ice valve ON light illuminates
on the switch when the valve is commanded open.
DISAG illuminates on the respective ENG 1/2/3 ANTI-ICE switch when the
valve position (open or closed) does not agree with the commanded position.
Momentary illumination of the DISAG light occurs while the valve is in transit.
The ESC inhibits an engine anti-ice DISAG annunciation while the FUEL switch
is selected OFF. The DISAG annunciation is also inhibited for up to 45 seconds
after the FUEL switch is selected ON (GE engines).
With the engine 2 anti-ice switch selected ON, if a leak is detected adjacent to
anti-ice ducting for engine 2, causing the valve to automatically close (KCE &
on), the alert ENG 2 A-ICE OFF is displayed.
With the engine 2 anti-ice on or commanded OFF and not verified off, if a leak
exists in the anti-ice ducting for engine 2, the alert ENG 2 A-ICE DUCT (KCA -
KCD) is displayed.
October 02, 2006
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