In the Boeing 737 MAX, any monitored faults that affect airplane dispatchability will trigger a flight deck alert or a status message, accompanied by a corresponding correlated maintenance message. Status messages appear on the pilot’s status display. System faults displayed at the status level should be resolved by MEL compliance or maintenance action before engine start.

The Boeing 737 MAX Display System (MDS) includes the Maintenance Awareness System (MAS) which gives information directly related to airworthiness and system information. The system includes the Status Message Page, Maintenance Data Page, and Maintenance Control Page. The Status Message page is displayed after you select the MAINT button.

I have compiled all status messages in alphabetical order, along with their descriptions, the associated MEL, and other troubleshooting information for quick dispatch.

A • B • D • E • F • G • M • N • P • R • S • T • Y

A

  • AFT CARGO LOADER RLY
    • The PSEU system has detected a fault in the aft cargo loader.
    • MEL 50-21-01
  • AIR/GND SYS
    • The PSEU system has detected a failure of the Air/Ground sensing system.
    • NO MEL
  • ALTN NOSE STEERING
    • The PSEU system has detected a failed alternate nose landing gear steering switch.
    • NO MEL
  • APU DOOR
    • The APU inlet door is not in commanded position.
    • MEL 49-15-01
  • APU GENERATOR
    • The APU generator rotating diode is failed.
    • MEL 24-21-01
  • APU OIL QTY
    • The APU oil quantity is below normal levels or oil quantity sensing has failed.
    • MEL N/A
  • AUTOSLAT FAIL SMYD 1
    • SMYD 1 has a fault that has failed its control of the autoslat system.
    • MEL 27-83-01
  • AUTOSLAT FAIL SMYD 2
    • SMYD 2 detects that it cannot command the Autoslat System.
    • MEL 27-83-01
  • AUTOSLAT FAIL
    • SMYD 1 and SMYD 2 have failures that render the autoslat system inoperative.
    • NO MEL

B

  • BLD CTRL BACKUP PROTECT L
    • Left Air Supply Controller (ASC) has detected a protection function failure on its backup card.
    • MEL 36-11-01-05
  • BLD CTRL BACKUP PROTECT R
    • Right Air Supply Controller (ASC) has detected a protection function failure on its backup card.
    • MEL 36-11-01-05
  • BLD CTRL CARD L – ENG DATA
    • Left Air Supply Controller (ASC) has detected that engine data (PS3, T3) is not available when left engine is ON.
    • MEL 36-11-01-06
  • BLD CTRL CARD R – ENG DATA
    • Right Air Supply Controller (ASC) has detected that engine data (PS3, T3) is not available when right engine is ON.
    • MEL 36-11-01-06
  • BLEED CTRL – ISO VALVE
    • Left or Right Integrated Air Systems Controller (IASC) has detected a failure on isolation valve discrete input.
    • MEL 36-13-02
  • BLEED CTRL BACKUP L
    • Left Air Supply Controller (ASC) has detected a complete failure on its backup card.
    • MEL 36-11-01-03
  • BLEED CTRL BACKUP R
    • Right Air Supply Controller (ASC) has detected a complete failure on its backup card.
    • MEL 36-11-01-03
  • BLEED CTRL ICING INHIB L
    • Inhibit function from the Air Supply Controller (ASC) to Engine Anti Ice (EAI) system has failed.
    • MEL 36-11-01-02
  • BLEED CTRL ICING INHIB R
    • Inhibit function from the Air Supply Controller (ASC) to Engine Anti Ice (EAI) system has failed.
    • MEL 36-11-01-02
  • BLEED CTRL L – ASC HEALTH
    • Left Integrated Air Systems Controller (IASC) has detected a failure on ASC controller health relay.
    • MEL 36-11-01-04
  • BLEED CTRL LIGHT OUTPUT L
    • Left Bleed light on the P5-10 flight deck panel is no longer functional.
    • MEL 36-11-05
  • BLEED CTRL LIGHT OUTPUT R
    • Right Bleed light on the P5-10 flight deck panel is no longer functional.
    • MEL 36-11-05
  • BLEED CTRL PRESS IND L
    • Analog output from Air Supply Controller (ASC) to pressure gauge on P5-10 panel has failed.
    • MEL 36-21-01
  • BLEED CTRL PRESS IND R
    • Analog output from Air Supply Controller (ASC) to pressure gauge on P5-10 panel has failed.
    • MEL 36-21-01
  • BLEED CTRL PRIMARY L
    • Left Primary Air Supply Controller Channel has failedor Left ASC is inactive for 2 minutes to both DPCs. Control is switched to backup controls.
    • MEL 36-11-01-01
  • BLEED CTRL PRIMARY R
    • Right Primary Air Supply Controller Channel has failedor Right ASC is inactive for 2 minutes to both DPCs. Control is switched to backup controls.
    • MEL 36-11-01-01
  • BLEED CTRL R – ASC HEALTH
    • Right Integrated Air Systems Controller (IASC) has detected a failure on ASC controller health relay.
    • MEL 36-11-01-04
  • BLEED FAMV L
    • Air Supply Controller (ASC) has detected that Fan Air Modulating Valve (FAMV) has failed.
    • MEL 36-12-01-01
  • BLEED FAMV R
    • Air Supply Controller (ASC) has detected that Fan Air Modulating Valve (FAMV) has failed.
    • MEL 36-12-01-01
  • BLEED HPSOV CTRL L
    • Air Supply Controller (ASC) has detected a failure of High Pressure ShutOff Valve (HPSOV) torque motor (open/short circuit) or HPSOV driver failed off. HPSOV will operate in pneumatic mode.
    • MEL 36-11-04-02
  • BLEED HPSOV CTRL R
    • Air Supply Controller (ASC) has detected a failure of High Pressure ShutOff Valve (HPSOV) torque motor (open/short circuit) or HPSOV driver failed off. HPSOV will operate in pneumatic mode.
    • MEL 36-11-04-02
  • BLEED HPSOV L
    • Air Supply Controller (ASC) has detected that Left High Pressure ShutOff Valve (HPSOV) is mechanically failed closed or failed open or HPSOV driver on IASC is erroneously driving the HPSOV fully closed or HPSOV is regulating to higher pressure.
    • MEL 36-11-04-01
  • BLEED HPSOV R
    • Air Supply Controller (ASC) has detected that Right High Pressure ShutOff Valve (HPSOV) is mechanically failed closed or failed open or HPSOV driver on IASC is erroneously driving the HPSOV fully closed or HPSOV is regulating to higher pressure.
    • MEL 36-11-04-01
  • BLEED IASC SOFTWARE CONFIG
    • Incompatible Bleed IASC software configuration detected.
  • BLEED PI SENSOR L
    • Air Supply Controller (ASC) detected a complete loss of Intermediate Manifold (PI) sensor due to the following1. PI low sense fault (4 seconds FCT) 2. PI high sense fault (4 seconds FCT) 3. PI sensing electrical (short/open) failure (3 seconds FCT) 4. PI drifted beyond a set threshold (latched, 20 seconds FCT) 5. PI Zero pressure test failed (latched, 9 seconds FCT).
    • MEL 36-11-02-02
  • BLEED PI SENSOR R
    • Air Supply Controller (ASC) detected a complete loss of Intermediate Manifold (PI) sensor due to the following1. PI low sense fault (4 seconds FCT) 2. PI high sense fault (4 seconds FCT) 3. PI sensing electrical (short/open) failure (3 seconds FCT) 4. PI drifted beyond a set threshold (latched, 20 seconds FCT) 5. PI Zero pressure test failed (latched, 9 seconds FCT).
    • MEL 36-11-02-02
  • BLEED PM SENSOR 2 L
    • Air Supply Controller (ASC) detected a complete loss of PM2 sensor reading due to the following reasons:1. Wiring failure (open/short) (3 seconds FCT) 2. Sensing element failure (3 seconds FCT) 3. High/low sense (4 seconds FCT) 4. Sensor drift beyond a set threshold (latched, 20 seconds FCT) 5. Failed zero pressure fault (latched, 9 seconds FCT).
    • MEL 36-11-02-01
  • BLEED PM SENSOR 2 R
    • Air Supply Controller (ASC) detected a complete loss of PM2 sensor reading due to the following reasons:1. Wiring failure (open/short) (3 seconds FCT) 2. Sensing element failure (3 seconds FCT) 3. High/low sense (4 seconds FCT) 4. Sensor drift beyond a set threshold (latched, 20 seconds FCT) 5. Failed zero pressure fault (latched, 9 seconds FCT).
    • MEL 36-11-02-01
  • BLEED PRSOV L
    • Air Supply Controller (ASC) has detected that the Pressure Regulating Shutoff Valve (PRSOV) is failed closed, failed open or PRSOV solenoid is detected as failed.
    • MEL 36-11-03
  • BLEED PRSOV R
    • Air Supply Controller (ASC) has detected that the Pressure Regulating Shutoff Valve (PRSOV) is failed closed, failed open or PRSOV solenoid is detected as failed.
    • MEL 36-11-03
  • BRAKE TEMP SYS
    • The brake temperature monitoring system has detected a fault. The BTMS may have partial or total loss of temperature monitoring.
    • MEL 32-46-01

D

  • DISPLAY UNIT INTERFACE
    • A display unit has an internal fault, a fiber optic cable is failed, or A429 data path is failed. This fault may result in one or more failed display units. This fault will be set when a display unit is unpowered. The internal fault includes various voltage checks, LED/LCD power supply checks, several specific IC status checks, and other monitors that are factored into the internal fault status.
    • MEL 31-62-01-01-01 / 31-62-01-01-02
  • DISPLAYS CONFIG DATA
    • MDS detects a configuration fault or a disagreement in the NVM stored data for the Aircraft Config Data entered via maintenance page.
    • NO MEL
  • DISPLAYS SOFTWARE CONFIG
    • Incompatible Displays software configuration detected.
    • NO MEL
  • DOOR AFT CARGO
    • The PSEU system has detected a fault in the aft cargo door indication system.
    • MEL 52-71-01-02
  • DOOR AFT ENTRY
    • The PSEU system has detected a fault in the aft entry door indication system.
    • MEL 52-71-01-01
  • DOOR AFT SERVICE
    • The PSEU system has detected a fault in the aft service door indication system.
    • MEL 52-71-01-01
  • DOOR EE ACCESS
    • The PSEU system has detected a fault in the EE access door indication system.
    • MEL 52-71-01-02
  • DOOR EMER EXIT PRGM PINS
    • The PSEU has detected an invalid door programming pin setting. Fault reporting for the affected door is not available.
    • MEL 52-71-02
  • DOOR EQUIP IND
    • The PSEU system has detected a fault in the equipment door indication system.
    • MEL 52-71-01-02
  • DOOR FWD ACCESS
    • The PSEU system has detected a fault in the FWD access door (EQUIP light on flight deck) indication system.
    • MEL 52-71-01-02
  • DOOR FWD CARGO
    • The PSEU system has detected a fault in the FWD cargo door indication system.
    • MEL 52-71-01-02
  • DOOR FWD ENTRY
    • The PSEU system has detected a fault in the FWD entry door indication system.
    • MEL 52-71-01-01
  • DOOR FWD SERVICE
    • The PSEU system has detected a fault in the forward service door indication system.
    • MEL 52-71-01-01
  • DOOR L OVERWING FLTLOCK
    • This message is set when the PSEU detects the L OVERWING (AFT or FWD) flightlock is inoperative.
    • MEL 52-22-01
  • DOOR L OVERWING
    • This message is set when the PSEU detects an open overwing door (AFT or FWD) locked switch while in air, or or the L OVERWING door lights (AFT or FWD) are inoperative.
    • MEL 52-71-01-04
  • DOOR R OVERWING FLTLOCK
    • This message is set when the PSEU detects the R OVERWING (AFT or FWD) flightlock is inoperative.
    • MEL 52-22-01
  • DOOR R OVERWING
    • This message is set when the PSEU detects an open right overwing door (AFT or FWD) locked switch while in air, or the R OVERWING door (AFT or FWD) light is inoperative.
    • MEL 52-71-01-04
  • DPC 1 HOT BATTERY
    • Hot battery power is not available to DPC 1.
    • NO MEL
  • DPC 1
    • DPC 1 has a hardware component that has failed or is faulted.
    • NO MEL
  • DPC 2 HOT BATTERY
    • Hot battery power is not available to DPC 2.
    • NO MEL
  • DPC 2
    • DPC 2 has a hardware component that has failed or is faulted.
    • NO MEL
  • DPC CROSSTALK BUS
    • DPC Cross-Talk bus is failed.
    • NO MEL

E

  • ENG 1 BAI/SBV VALVE
    • Engine 1 Booster Anti-Ice (BAI) / Start Bleed Valve (SBV) position disagrees with the commanded position, or the BAI/SBV actuator torque motor is failed on the EEC Channel-in-Control, or the BAI/SBV VDT feedback signal is invalid on both EEC channels.
    • NO MEL
  • ENG 1 CONTROL
    • Engine 1 EEC is in a “No Dispatch” configuration. EEC may be operating with a limited set of engine control parameters and may not be capable of controlling all aspects of engine operation. or Engine 1 EEC is in a “No Dispatch” configuration. EEC may be operating with a limited set of engine control parameters and may not be capable of controlling all aspects of engine operation.
    • NO MEL
  • ENG 1 EEC COOLING SYS
    • Engine 1 EEC cooling system (blower 1 and blower 2) is failed.
    • MEL 75-23-01
  • ENG 1 EEC OVERHEAT
    • Engine 1 EEC channels A and B have internal temperatures that exceed their operating limits.
    • NO MEL
  • ENG 1 FAN COMP OVHT SENSOR
    • Engine 1 EEC has detected a failure of the duct leak temperature sensors.
    • NO MEL
  • ENG 1 FAN COMP OVHT
    • Engine 1 EEC has detected a fan compartment overheat.
    • NO MEL
  • ENG 1 FUEL FILTER SENSOR
    • Engine 1 differential pressure sensor for detecting an impending bypass of the engine fuel filter is failed.
    • MEL 73-34-01-02
  • ENG 1 FUEL FILTER
    • Engine 1 differential pressure across the fuel filter indicates an impending or actual filter bypass condition.
    • NO MEL
  • ENG 1 FUEL MAIN HX SENSOR
    • Engine 1 differential pressure sensor for detecting an impending bypass of the engine fuel cooled oil cooler (FCOC) heat exchanger is failed.
    • MEL 73-34-01-01
  • ENG 1 FUEL MAIN HX
    • Engine 1 differential pressure across the main fuel cooled oil cooler (FCOC) heat exchanger indicates an actual FCOC bypass condition.
    • NO MEL
  • ENG 1 FUEL SPLIT VALVE
    • Engine 1 Fuel splitting Pilot Metering Valve (PMV) is failed open or closed or the valve position sensor has failed in both channels or there is a torque motor fault.
    • NO MEL
  • ENG 1 FUEL STRAINER SENSOR
    • Engine 1 differential pressure sensor for detecting an impending bypass of the engine fuel strainer is failed.
    • MEL 73-11-01
  • ENG 1 FUEL STRAINER
    • Engine 1 differential pressure across the fuel strainer indicates an actual filter bypass condition or fuel strainer impending bypass condition.
    • NO MEL
  • ENG 1 HPTACC VALVE
    • Engine 1 High Pressure Turbine Active Clearance Control (HPTACC) Valve is failed open or closed or the valve position sensor has failed in both channels or there is a torque motor fault.
    • MEL 75-24-01-01
  • ENG 1 IGNITER L
    • Engine 1 failed to light using the left igniter or no power to the left igniter or dual EEC relay failed open.
    • MEL 74-00-01-01
  • ENG 1 IGNITER R
    • Engine 1 failed to light using the right igniter or no power to the right igniter or dual EEC relay failed open fault.
    • MEL 74-00-01-02
  • ENG 1 LPTACC VALVE
    • Engine 1 Low Pressure Turbine Active Clearance Control (LPTACC) Valve is failed open or closed or the valve position sensor has failed in both channels or there is a torque motor fault.
    • NO MEL
  • ENG 1 OIL DEBRIS SENSOR
    • Engine 1 oil chip detector sensor is failed.
    • MEL 79-21-01-01
  • ENG 1 OIL DEBRIS
    • Engine 1 oil chip detector contains a number of metal chips which exceeds the allowed cumulative or per flight thresholds, indicating the possible onset of a bearing problem.
    • MEL 79-21-01
  • ENG 1 OIL FILTER SENSOR
    • Engine 1 differential pressure sensor for detecting an impending bypass of the engine oil filter is failed.
    • MEL 79-35-01
  • ENG 1 OIL PRESS SENSOR
    • Engine 1 oil pressure sensor is failed. Results in loss of engine oil pressure flight deck display.
    • NO MEL
  • ENG 1 OIL TEMP SENSOR
    • Engine 1 oil temperature sensor is failed. Results in loss of engine oil temperature flight deck display.
    • NO MEL
  • ENG 1 OVERSPEED PROTECT
    • Engine 1 Electronic Overspeed (EOS) / Thrust Control Malfunction Accomodation (TCMA) protection system built in test or functional test has failed or neither of the tests have been performed.
    • NO MEL
  • ENG 1 PSS OVERHEAT
    • Engine 1 Pressure Subsystem (PSS) internal temperature has exceeded its operating limit.
    • NO MEL
  • ENG 1 REVERSER
    • ENGINE 1 THRUST REVERSER SYSTEM ANOMALY. Engine 1 thrust reverser control system has a reduced level of safety for preventing an uncommanded deployment, or has lost position indication.
    • MEL 78-31-01
  • ENG 1 TBV
    • Engine 1 Transient Bleed Valve (TBV) is failed open or closed or the valve position sensor has failed in both channels or there is a torque motor fault.
    • NO MEL
  • ENG 1 VIBRATION MONITOR
    • Engine 1 vibration monitoring function is failed. Results in loss of engine vibration flight deck display.
    • MEL 77-31-01
  • ENG 2 BAI/SBV VALVE
    • Engine 2 Booster Anti-Ice (BAI) / Start Bleed Valve (SBV) position disagrees with the commanded position, or the BAI/SBV actuator torque motor is failed on the EEC Channel-in-Control, or the BAI/SBV VDT feedback signal is invalid on both EEC channels.
    • NO MEL
  • ENG 2 CONTROL
    • Engine 2 EEC is in a “No Dispatch” configuration. EEC may be operating with a limited set of engine control parameters and may not be capable of controlling all aspects of engine operation. or Engine 2 EEC is in a “No Dispatch” configuration. EEC may be operating with a limited set of engine control parameters and may not be capable of controlling all aspects of engine operation.
    • NO MEL
  • ENG 2 EEC COOLING SYS
    • Engine 2 EEC cooling system (blower 1 and blower 2) is failed.
    • MEL 75-23-01
  • ENG 2 EEC OVERHEAT
    • Engine 2 EEC channels A and B have internal temperatures that exceed their operating limits.
    • NO MEL
  • ENG 2 FAN COMP OVHT SENSOR
    • Engine 2 EEC has detected a failure of the duct leak temperature sensors.
    • NO MEL
  • ENG 2 FAN COMP OVHT
    • Engine 2 EEC has detected a fan compartment overheat.
    • NO MEL
  • ENG 2 FUEL FILTER SENSOR
    • Engine 2 differential pressure sensor for detecting an impending bypass of the engine fuel filter is failed.
    • MEL 73-34-01-02
  • ENG 2 FUEL FILTER
    • Engine 2 differential pressure across the fuel filter indicates an impending or actual filter bypass condition.
    • NO MEL
  • ENG 2 FUEL MAIN HX SENSOR
    • Engine 2 differential pressure sensor for detecting an impending bypass of the engine fuel cooled oil cooler (FCOC) heat exchanger is failed.
    • MEL 73-34-01-01
  • ENG 2 FUEL MAIN HX
    • Engine 2 differential pressure across the main fuel cooled oil cooler (FCOC) heat exchanger indicates an actual FCOC bypass condition.
    • NO MEL
  • ENG 2 FUEL SPLIT VALVE
    • Engine 2 Fuel splitting Pilot Metering Valve (PMV) is failed open or closed or the valve position sensor has failed in both channels or there is a torque motor fault.
    • NO MEL
  • ENG 2 FUEL STRAINER SENSOR
    • Engine 2 differential pressure sensor for detecting an impending bypass of the engine fuel strainer is failed.
    • MEL 73-11-01
  • ENG 2 FUEL STRAINER
    • Engine 2 differential pressure across the fuel strainer indicates an actual filter bypass condition or fuel strainer impending bypass condition.
    • NO MEL
  • ENG 2 HPTACC VALVE
    • Engine 1 High Pressure Turbine Active Clearance Control (HPTACC) Valve is failed open or closed or the valve position sensor has failed in both channels or there is a torque motor fault.
    • MEL 75-24-01-01
  • ENG 2 IGNITER L
    • Engine 2 failed to light using the left igniter or no power to the left igniter or dual EEC relay failed open.
    • MEL 74-00-01-01
  • ENG 2 IGNITER R
    • Engine 2 failed to light using the right igniter or no power to the right igniter or dual EEC relay failed open fault.
    • MEL 74-00-01-02
  • ENG 2 LPTACC VALVE
    • Engine 2 Low Pressure Turbine Active Clearance Control (LPTACC) Valve is failed open or closed or the valve position sensor has failed in both channels or there is a torque motor fault.
    • NO MEL
  • ENG 2 OIL DEBRIS SENSOR
    • Engine 2 oil chip detector sensor is failed.
    • MEL 79-21-01-01
  • ENG 2 OIL DEBRIS
    • Engine 2 oil chip detector contains a number of metal chips which exceeds the allowed cumulative or per flight thresholds, indicating the possible onset of a bearing problem.
    • MEL 79-21-01
  • ENG 2 OIL FILTER SENSOR
    • Engine 2 differential pressure sensor for detecting an impending bypass of the engine oil filter is failed.
    • MEL 79-35-01
  • ENG 2 OIL PRESS SENSOR
    • Engine 2 oil pressure sensor is failed. Results in loss of engine oil pressure flight deck display.
    • NO MEL
  • ENG 2 OIL TEMP SENSOR
    • Engine 2 oil temperature sensor is failed. Results in loss of engine oil temperature flight deck display.
    • NO MEL
  • ENG 2 OVERSPEED PROTECT
    • Engine 2 Electronic Overspeed (EOS) / Thrust Control Malfunction Accomodation (TCMA) protection system built in test or functional test has failed or neither of the tests have been performed.
    • NO MEL
  • ENG 2 PSS OVERHEAT
    • Engine 2 Pressure Subsystem (PSS) internal temperature has exceeded its operating limit.
    • NO MEL
  • ENG 2 REVERSER
    • ENGINE 2 THRUST REVERSER SYSTEM ANOMALY. Engine 2 thrust reverser control system has a reduced level of safety for preventing an uncommanded deployment, or has lost position indication.
    • MEL 78-31-01
  • ENG 2 TBV
    • Engine 2 Transient Bleed Valve (TBV) is failed open or closed or the valve position sensor has failed in both channels or there is a torque motor fault.
    • NO MEL
  • ENG 2 VIBRATION MONITOR
    • Engine 2 vibration monitoring function is failed. Results in loss of engine vibration flight deck display.
    • MEL 77-31-01

F

  • FLAP TE POSN DEGRADED IND
    • Description not available.
    • NO MEL

G

  • GEAR CONTROL 1
    • The PSEU system has detected a fault in the landing gear control system 1.
    • MEL 32-31-02A
  • GEAR CONTROL 2
    • The PSEU system has detected a fault in the landing gear control system 2.
    • MEL 32-31-02A
  • GEAR CONTROL
    • The PSEU system has detected a fault in the landing gear control system.
    • MEL 32-31-02B
  • GEAR IND
    • The PSEU system has detected an inoperative flight deck landing gear indication light.
    • NO MEL
  • GEAR LEVER LATCH
    • The PSEU system has detected a failure of the flight deck gear lever latch solenoid coil.
    • NO MEL
  • GEAR LEVER SW
    • The PSEU system has detected a disagree between gear lever position signals which will not prevent normal gear extension/retraction.
    • MEL 32-31-03
  • GEAR LEVER
    • The PSEU system has detected a disagreement between gear lever position signals which prevents normal gear extension/retraction.
    • NO MEL
  • GEAR WARN ALTIMETER
    • The PSEU system has detected a fault in the landing gear configuration warning related to altimeter.
    • NO MEL
  • GEAR WARN SYS
    • The PSEU system has detected a failure of the landing gear configuration warning system.
    • NO MEL
  • GEAR WARN THROTTLE SW
    • The PSEU system has detected a fault in the landing gear configuration warning related to throttle thrust resolver angle switch pack.
    • NO MEL
  • GEAR XFR VALVE CONTROL
    • The PSEU system has detected a failure of the landing gear transfer valve circuit.
    • NO MEL
  • GROUND SPOILER CONTROL
    • This message is set for a detected failure of the Ground Spoiler Control Module (GSCM).
    • NO MEL

M

  • MAINTENANCE ENABLE
    • The ground test maintenance switch is not in the normal position.
    • MEL N/A
  • MLG L SENSOR
    • The PSEU system has detected a failure of the left main landing gear sensors.
    • NO MEL
  • MLG R SENSOR
    • The PSEU system has detected a failure of the right main landing gear sensors.
    • NO MEL

N

  • NLG SENSOR
    • The PSEU system has detected a failure of the nose landing gear locked or down sensors.
    • NO MEL

P

  • PACK FLOW CTRL SENSOR L
    • Faults in the flow sensor or flow sensor interface have made the flow sensor no longer usable. Opposite flow sensor data is used, if available.
    • MEL 21-51-04
  • PACK FLOW CTRL SENSOR R
    • Faults in the flow sensor or flow sensor interface have made the flow sensor no longer usable. Opposite flow sensor data is used, if available.
    • MEL 21-51-04
  • PACK FLOW CTRL VALVE L
    • The pack flow control valve (FCV) is failed open or the FCV closed limit switch is failed. This message is used to capture the air conditioning and air supply maintenance page. Note: the Pack light will also illuminate.
    • MEL 21-51-02
  • PACK FLOW CTRL VALVE R
    • The pack flow control valve (FCV) is failed open or the FCV closed limit switch is failed. This message is used to capture the air conditioning and air supply maintenance page. Note: the Pack light will also illuminate.
    • MEL 21-51-02
  • PACK FLOW PRIMARY L
    • Faults in the flow control valve, driver or primary controller have made electronic flow control inoperational.
    • MEL 21-51-02-01
  • PACK FLOW PRIMARY R
    • Faults in the flow control valve, driver or primary controller have made electronic flow control inoperational.
    • MEL 21-51-02-01
  • PACK IASC COMM L
    • Loss of communication between the left Integrated Air Systems Controller (IASC) Pack Flow and Temperature Controller (PFTC) and both Display Processing Computers (DPCs) when the Left controller is still on primary control.
    • MEL 21-51-08
  • PACK IASC COMM R
    • Loss of communication between the Right Integrated Air Systems Controller (IASC) Pack Flow and Temperature Controller (PFTC) and both Display Processing Computers (DPCs) when the Right controller is still on primary control.
    • MEL 21-51-08
  • PACK IASC SOFTWARE CONFIG
    • Incompatible Pack IASC software configuration detected.
  • PACK RAM AIR SYSTEM L
    • RAM air system is inoperative due to a failure of the inlet or exit Smart Ram Air Door Actuator (SRADA).
    • MEL 21-51-09
  • PACK RAM AIR SYSTEM R
    • RAM air system is inoperative due to a failure of the inlet or exit Smart Ram Air Door Actuator (SRADA).
    • MEL 21-51-09
  • PACK TEMP CTRL PRIMARY L
    • Pack temperature control is inoperative due to a failure related to the temperature control valve (TCV). Message includes both valve and controller driver faults.
    • MEL 21-51-05
  • PACK TEMP CTRL PRIMARY R
    • Pack temperature control is inoperative due to a failure related to the temperature control valve (TCV). Message includes both valve and controller driver faults.
    • MEL 21-51-05
  • PSEU AIR/GND OVRD ENABLE
    • The PSEU system AIR/GND override is active.
    • MEL N/A
  • PSEU COMM
    • The Display Processing computer (DPC) has detected a complete loss of communication from the PSEU (ARINC 429).
    • NO MEL
  • PSEU FAIL
    • The PSEU system has detected an internal fault.
    • NO MEL
  • PSEU POWER
    • The PSEU system is not supplied with 28VDC power from one of two sources (ground service bus or battery bus).
    • NO MEL

R

  • REMOTE LIGHT SENSOR
    • Left and right remote light sensors failed. This message is only set if the DUs are powered on and the sensors are failed.
    • MEL 31-62-02

S

  • SPEEDBRAKE LEVER XDCR
    • This message is set for a failure of two or more speedbrake lever position transducers.
    • NO MEL
  • SPOILER CONTROL CHANNEL
    • This message is triggered by a SCE Power-Up test fault, NVM device fault, or incorrect program pin combination that affects a single processing lane. The message can also be set by multiple discrete inputs or outputs faulted across more than one lane.
    • MEL 27-61-01-01
  • SPOILER CONTROL SYSTEM
    • This message is set with loss of Spoiler Control Electronics processing integrity which would render Ground and Flight Spoilers inoperative.
    • NO MEL
  • SPOILER CTRL WHEEL XDCR
    • This message is set for a failure of two or more first officer’s control wheel position transducers.
    • NO MEL
  • SPOILER DESCENT SPEEDBRAKE
    • This message is set for a failure of the Emergency Descent Speedbrakes (EDS) control law causing the control law to become inoperative.
    • MEL 27-61-03
  • SPOILER DIRECT LIFT CTRL
    • This message is set for a failure of the Direct Lift Control (DLC) control Law due to insufficient inputs.
    • NO MEL
  • SPOILER LOAD ALLEVIATION
    • This message is set for a failure of the Maneuver Load Alleviation (MLA) control law causing the control law to become inoperative.
    • MEL 27-61-02
  • SPOILER PAIR 2/11
    • Spoiler 2 on the Left Wing and Spoiler 11 on the Right Wing are inoperative.
    • MEL 27-61-01
  • SPOILER PAIR 3/10
    • Spoiler 3 on the Left Wing and Spoiler 10 on the Right Wing are inoperative.
    • MEL 27-61-01
  • SPOILER PAIR 4/9
    • Spoiler 4 on the Left Wing and Spoiler 9 on the Right Wing are inoperative.
    • MEL 27-61-01
  • SPOILER PAIR 5/8
    • Spoiler 5 on the Left Wing and Spoiler 8 on the Right Wing are inoperative.
    • NO MEL
  • STALL WARNING SYS L
    • Loss of captain’s stall warning function on left SMYD.
    • NO MEL
  • STALL WARNING SYS R
    • Loss of first officer’s stall warning function on right SMYD.
    • NO MEL
  • STALL WARNING SYS
    • Stall warning functionality is still available, but the SMYD AOA Maintenance Monitor has tripped.

T

  • TAKEOFF CONFIG
    • The PSEU system has detected a failure of the takeoff configuration sensing system.
    • NO MEL
  • TAKEOFF WARN FAIL
    • The PSEU system has detected a failure of the takeoff configuration warning system.
    • NO MEL
  • TAT DISAGREE
    • The FMC has detected an error in the ADIRU’s Total Air Temperature Sensor.
    • NO MEL
  • TIRE PRESS SYS
    • The landing gear tire pressure monitoring system has detected a fault.
    • MEL 32-49-01
  • TRIM AIR MOD VLV AFT CAB
    • The AFT zone temperature control loop is inoperative due to a failure which makes the Trim Air Valve (TAV) inoperational.
    • MEL 21-61-01
  • TRIM AIR MOD VLV CONT CAB
    • The Flight Deck temperature control loop is inoperative due to a failure which makes the Trim Air Valve (TAV) inoperational. The ZONE TEMP light for the flight deck also illuminates.
    • MEL 21-61-01
  • TRIM AIR MOD VLV FWD CAB
    • The FWD zone temperature control loop is inoperative due to a failure which makes the Trim Air Valve (TAV) inoperational.
    • MEL 21-61-01

Y

  • YAW DAMPER SYS
    • A fault in SMYD 1 or SMYD 2 has rendered the yaw damper inoperative.
    • MEL 22-23-01
AviationHunt Team

Our team at AviationHunt is a group of aviation experts and enthusiasts. We aim to provide aviation insights, technical notes, best aircraft maintenance practices, and aviation safety tips.