GEAR SYS FAIL
(Caution)

The indication function or control function does not operate and when one or more of the conditions that follow occur:

• Two inputs from one or more pairs of landing gear downlock inputs have a failure. These inputs can be sensor faults or internal faults of the LGECU input signal-path. The two conditions, a sensor fault and an internal fault in related paths of the same pair of signal-paths, can cause these inputs.
• Two outputs from one or more pairs of landing gear downlock outputs have a failure. These outputs can be internal faults of the LGECU output signal-path or external faults. The two conditions, an internal fault and an external fault in related paths of the same pair of signal paths, can cause these outputs.
• WOW on-ground shows and one or more landing gear uplock inputs have a failure. These inputs can be sensor faults or internal faults of the LGECU input signal-path.
• WOW on-ground shows and one or both nose gear center inputs have a failure. These inputs can be sensor faults or internal faults of the LGECU input signal-path.
• WOW on-ground shows and one or more landing gear door open inputs have a failure. These inputs can be sensor faults or internal faults of the LGECU input signal-path.
• One or the two inputs of the landing gear control handle has a failure. The external faults or internal faults of the LGECU input signal-path can cause these inputs. An external fault and an internal fault in related signal paths can cause these inputs. If an input condition is incorrect, but not with a short-circuit or an open circuit, the LGECU will not know that this is an external fault. The LGECU makes the decision that it is an internal fault and a fault message is sent to CAIMS that incorrectly identifies the LGECU as the source of the failure.
• One or more of the outputs of the landing gear selector-valve has a failure. These outputs can be internal faults of the LGECU output signal-path or external faults. The two conditions, an internal and an external fault, can cause these outputs.
• One or more of the outputs of the landing gear door selector-valve has a failure. These outputs can be internal faults of the LGECU output signal-path or external faults. The two conditions, an internal and an external fault, can also cause these outputs.
• The side-brace control-valve output is in a fault condition. An internal fault of the LGECU output signal-path or an external fault can cause this output.

A fault condition of the landing gear downlock inputs will cause the related downlock indication function to fail. Also, a fault condition of the outputs of the landing gear downlock will cause the related downlock indication function to fail. An input and an output fault condition in related paths of the same pair of signal-paths will cause the related downlock indication function to fail.

An outputs fault condition of the landing gear selector-valve will cause the related landing gear control function to fail. Also, an outputs fault condition of the landing gear door selector-valve will cause the related landing gear control function to fail. An output fault condition of the side-brace control-valve will cause the related landing gear control function to fail.

• Nose Gear Downlock Proximity Sensors
• Main Gear Downlock Proximity Sensors (one pair, or the two pairs)
• Landing-Gear Electronic Control-Unit (LG ECU)
• Data Acquisition Units (DAU)
• Nose Gear Uplock Proximity Sensor
• Main Gear Uplock Proximity Sensor
• Nose Gear Center Proximity Sensor
• Nose Gear Door Open Proximity Sensor
• Main Gear Door Open Proximity Sensor
• Landing Gear Control Handle
• Landing Gear Selector Valve
• Landing Gear Door Selector Valve
• Side Brace Control Valve
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

1. Using the PMAT, access the Active Faults/Stored Faults as per AMM Tasks.
2. Select related CAIMS message below:
   Select an Item3230112EL - NOSE-GEAR CENTERED-LEFT SENSOR/WRG3230113EL - NOSE-GEAR CENTERED-RIGHT SENSOR/WRG3230114EL - NOSE-GEAR DOWNLOCK SENSOR A/WRG3230115EL - NOSE-GEAR UPLOCK SENSOR/WRG3230116EL - NOSE-GEAR DOOR-OPEN SENSOR/WRG3230120EL - R MAIN-GEAR UPLOCK SENSOR/WRG3230124EL - R MAIN-GEAR DOOR-OPEN SENSOR/WRG3230126EL - R MAIN-GEAR DOWNLOCK SENSOR A/WRG3230127EL - L MAIN-GEAR UPLOCK SENSOR/WRG3230131EL - L MAIN-GEAR DOOR-OPEN SENSOR/WRG3230134EL - LG ECU (CHAN A) INTERNAL FAULT3230193EL - LGECU A/WRG/LDG GR SEL VALVE #3 UP3230194EL - LGECU A/WRG/LDG GR SEL VALVE #3 DN3230195EL - LGECU A/WRG/SIDEBRACE CONTROL-VALVE3230196EL - LGECU A/WRG/GR DRS SEL VALVE(CLOSE)3230197EL - LGECU A/WRG/GR DRS SEL VALVE (OPEN)3230198EL - LGECU A/WRG/GR DRS SEL V (OPEN RTN)3230201EL - LG ECU CH A/WRG/LDG GR CTRL HDL-EXT3230202EL - LG ECU CH A/WRG/LDG GR CTRL HDL-RET3230211EL - LGECU A/WRG/LDG GR SEL VALVE #2 UP3230212EL - LGECU A/WRG/LDG GR SEL VALVE #2 DN3230214EL - LG ECU CH A (NLG DNLOCK IND) FAULT3230215EL - LG ECU CH A (R MLG DNLK IND) FAULT3230216EL - LG ECU CH A (L MLG DNLK IND) FAULT3230253EL - LDG GR SELECTOR VALVE #3/WRG (UP)3230254EL - LDG GR SELECTOR VALVE #3/WRG (DOWN)3230255EL - SIDE BRACE CONTROL-VALVE/WRG (OPEN)3230256EL - LDG GR DOOR SEL VALVE/WRG (CLOSE)3230257EL - LDG GR DOOR SEL VALVE/WRG (OPEN)3230258EL - LDG GR DR SEL VALVE/WRG (OPEN RTN)3230262EL - LDG GR SELECTOR VALVE #2/WRG (UP)3230263EL - LDG GR SELECTOR VALVE #2/WRG (DOWN)3230264EL - DAU 1/WRG (NLG DOWNLOCK A IND)3230265EL - DAU 1/WRG (R MLG DOWNLOCK A IND)3230266EL - DAU 1/WRG (L MLG DOWNLOCK A IND)3230273EL - LDG GR CTRL HDL/WRG-INPUTS DISAGREE3230290EL - L MAIN-GEAR DOWNLOCK SENSOR A/WRG3231111EL - NOSE-GEAR DOWNLOCK SENSOR B/WRG3231114EL - L MAIN-GEAR DOWNLOCK SENSOR B/WRG3231133EL - LG ECU (CHAN B) INTERNAL FAULT3231181EL - LG ECU CH B (NLG DNLOCK IND) FAULT3231182EL - LG ECU CH B (R MLG DNLK IND) FAULT3231183EL - LG ECU CH B (L MLG DNLK IND) FAULT3231212EL - DAU 2/WRG (NLG DOWNLOCK B IND)3231213EL - DAU 2/WRG (R MLG DOWNLOCK B IND)3231214EL - DAU 2/WRG (L MLG DOWNLOCK B IND)3231223EL - LG ECU CHAN A LOSS OF DC & BATT PWR3231230EL - R MAIN-GEAR DOWNLOCK SENSOR B/WRG