*
The airplane is on the ground

*
The heater is on for 25 seconds.

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D633W101-BEJ  Sep 05/2002 

ICE DETECTION SYSTEM -ICE DETECTORS

The detectors have circuits that monitor operation and give a fault signal if necessary. The detectors also have BIT circuits that become active by a push-to-test (PTT) signal from the ACIPS.
See the wing anti-ice section for more information about wing anti-ice (SECTION 30-11). See the engine anti-ice section for more information about engine anti-ice (SECTION 30-21).
Training Information Point
WARNING: THE PROBE OF THE ICE DETECTOR CAN CAUSE SERIOUS BURNS WHEN THE HEATER IS ON.
CAUTION: THIS EQUIPMENT CONTAINS DEVICES THAT CAN
BE DAMAGED BY ELECTROSTATIC DISCHARGE
(ESD). ESD HANDING PRECAUTIONS REQUIRED.
EFFECTIVITY BEJ ALL  30-81-00 
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D633W101-BEJ  Sep 05/2002 

777 AIRCRAFT MAINTENANCE MANUAL

ICE DETECTION SYSTEM -ICE DETECTORS

EFFECTIVITY BEJ ALL  30-81-00 
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D633W101-BEJ  Jan 05/2002 

777 AIRCRAFT MAINTENANCE MANUAL

THIS PAGE IS INTENTIONALLY LEFT BLANK

30-81-00

Page 8 D633W101-BEJ Jan 05/2002

ICE DETECTION SYSTEM -FUNCTIONAL DESCRIPTION

General
The ice detection system (IDS) has a left ice detector and a right ice detector. The detectors get 115v ac from the left or right main bus. The left detector has connections to the left EAI ACIPS control card. The right detector has connections to the right EAI ACIPS control card. These are the connections:
*
Fault signal (output)

*
Engine icing signal (output)

*
Wing icing signal (output)

*
Push-to-test (PTT) signal (input)

*
Air/ground signal (input).

These are the three ACIPS control cards:
*
Left engine anti-ice ACIPS control card

*
Right engine anti-ice ACIPS control card

*
Wing anti-ice ACIPS control card.

Each card connects to the other two cards through the systems ARINC 629 buses. The left and right EAI ACIPS control cards do these functions for the IDS:
*
Does a power-up test (automatic)

*
Does a periodic test (automatic)

*
Does the PTT (MAT, ground test)

*
Sets the mode of operation (ground or air)

*
Gives fault information to AIMS for indications

*
Resets latched faults (during pwr-up, gnd test, or after the IDS gives a fault signal).

EFFECTIVITY
BEJ ALL

See the wing anti-ice section for more information about wing anti-ice ACIPS control card (SECTION 30-11). See the engine anti-ice section for more information about engine anti-ice ACIPS control card and system test (SECTION 30-21).
Ground Operation
When the IDS operates in the ground mode (on the ground and airspeed < 0.180 mach), the wing and engine icing output signals are inhibited. The PTT input and the fault output signals are enabled. The ACIPS continuously does a check of the operation of the ice detectors.
The PTT input signal operates when these conditions occur:
*
ACIPS gets power

*
IDS gets power

*
IDS gives a fault signal

*
System test of the EAI system from the MAT.

The PTT makes the applicable ice detector and the ACIPS do a full check of the ice detector and its interfaces.
Air Operation
When the IDS operates in the air mode, the wing and engine icing and the fault output signals are enabled. The PTT input signal is inhibited.
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Page 9 D633W101-BEJ Sep 05/2002

ICE DETECTION SYSTEM -FUNCTIONAL DESCRIPTION

An engine icing signal or an engine and wing icing signal can come from either or both ice detectors. The signal from one detector goes directly to one EAI ACIPS control card. The card that receives the signal(s) directly, sends the signal(s) to the other two ACIPS control cards. The cards use the information about icing with other airplane conditions to calculate when to turn on the EAI and WAI systems. The cards also use the information about icing to control related EICAS messages for the EAI and WAI systems. See the wing anti-ice section for more information about the wing anti-ice system operation and messages (SECTION 30-11). See the engine anti-ice section for more information about the engine anti-ice system operation and messages (SECTION 30-21).
Faults
The detectors and the EAI ACIPS control cards can find faults. If there is a fault, the ACIPS sends the fault information to AIMS. AIMS shows a status message, ICE DETECTOR L (R) for the detector that has a fault. If both detectors fail, AIMS shows an advisory message, ICE DETECTORS. AIMS also shows maintenance messages that help you isolate the fault.
　
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