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(WARNING)
RED MESSAGE (CAUTION)
AMBER MESSAGE (ADVISORY)
CYAN MESSAGE (STATUS)
WHITE MESSAGE Require immediate crew attention. These messages are accompanied by flashing master warning, triple chime attenson with or without voice message or dedicated tone. Require immediate crew awareness and future crew action may be required in the form of alternate system selection or performance limitation. These message are accompanied by flashing master caution and a single chime. Indicate safe or normal system operation which require crew awareness, over and above the dark cockpit philosophy. Indicate minor failures or reduction in systems capability, which require no crew action.

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07/01/21

Message Overview:

Message Name:

UNRELIABLE/FLUCTUATING AIRSPEED

Message Code: 341OBS002
Effectivity: All
System: Air Data Computer (ADC) System
System Description: 34-11-00
Schematic Diagram: 34-11-00 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Wiring Diagram: 34-11-01 [ Global Express ]  [ G5000 ]  [ Global XRS ]

Message Description:

Large Air Data Computer (ADC)/ Integrated Standby Instrument (ISI) airspeed difference between Primary Flight Display (PFD) and/or ISI is detected by flight crew and Aircraft Quick Reference Handbook (QRH) AVNC 02-21 or Flight Crew Operating Manual (FCOM) 03-12 procedure were used.

Symptoms of unreliable airspeed may include:

  • Pitch attitude, thrust setting or external noise not consistent with indicated airspeed.
  • Loss of multiple airspeed indications.
  • Airspeed indication(s) remain constant regardless of pitch or thrust adjustments
  • Presence of ALL ADC MISCP (Caution) or IAS annunciation on the PFD.

Possible Causes:

  • Visual drains are full of water
  • Pitot line P1, P2, P3 and P STBY
  • Static line S1, S2, S3 and S STBY
  • Integrated Standby Instrument (ISI)
  • Air Data Computer (ADC) 1, 2 and/or 3

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

Quick Links:

Pitot Line P1 Contamination Removal AMM 34-11-01-100-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Pitot Line P2 Contamination Removal AMM 34-11-01-100-802 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Pitot Line P3 Contamination Removal AMM 34-11-01-100-803 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Pitot Line P STBY Contamination Removal AMM 34-11-01-100-804 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Static Line P1 S1/P STBY S2 Contamination Removal AMM 34-11-01-100-805 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Static Line P2 S1/P3 S2 Contamination Removal AMM 34-11-01-100-806 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Static Line P3 S1/P2 S2 Contamination Removal AMM 34-11-01-100-807 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Static Line P STBY S1/P1 S2 Contamination Removal AMM 34-11-01-100-808 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Servicing of the Visual Drains AMM 34-11-03-616-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Removal of the Micro Air-Data Computers AMM 34-11-09-000-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Installation of the Micro Air-Data Computers AMM 34-11-09-400-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Removal of the Standby Airspeed/Altimeter Indicator AMM 34-12-01-000-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Installation of the Standby Airspeed/Altimeter Indicator AMM 34-12-01-400-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Access to Active Faults AMM 45-45-00-970-802 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Access to Stored Faults AMM 45-45-00-970-803 [ Global Express ]  [ G5000 ]  [ Global XRS ]

Troubleshooting Recommendations:

  1. Do the contamination removal of the pitot and static lines as follows:

    1. Do the contamination removal of the pitot line P1 (AMM TASK 34-11-01-100-801)
    2. Do the contamination removal of the pitot line P2 (AMM TASK 34-11-01-100-802)
    3. Do the contamination removal of the pitot line P3 (AMM TASK 34-11-01-100-803)
    4. Do the contamination removal of the pitot line P STBY (AMM TASK 34-11-01-100-804)
    5. Do the contamination removal of the static line P1 S1/S2 (AMM TASK 34-11-01-100-805)
    6. Do the contamination removal of the static line P2 S1/S2 (AMM TASK 34-11-01-100-806)
    7. Do the contamination removal of the static line P3 S1/S2 (AMM TASK 34-11-01-100-807)
    8. Do the contamination removal of the static line P STBY S1/S2 (AMM TASK 34-11-01-100-808)
      NOTE: This step should be performed regardless if contamination is found in the moisture traps.

  2. Use the PMAT to access CAIMS and view stored or active faults. Check for any Integrated Standby Instrument (ISI) or Air Data Computer (ADC) fault messages.

    1. If fault messages are found, use SmartFix Plus to troubleshoot these codes.
    2. If no fault messages are found, continue with next step.

  3. Replace the ISI. Is the fault still present?

    1. If YES, continue with next step.
    2. If NO, do close out.

  4. Replace the Air Data Computer associated to the unreliable indication.
  5. Do close out.

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