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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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Quick Links

06/30/21

Message Overview:

Message Name:

ALTITUDE INDICATION SPLIT / ALT MISCOMPARE ON PFD ALTITUDE TAPE

Message Code: 341OBS001
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:

  • Altitude Indication Split:

    • Flight Deck Effect shows Barometric altitude indications difference (altitude split) between Altimetry Systems as selected for view on the Primary Flight Displays (PFDs) and the Standby Altitude Indicator

  • ALT Miscompare:

    • The above altitude split condition may also be associated with the amber ALT miscompare annunciation on the PFD altitude tape. ALT Miscompare shows when Integrated Avionics Computer (IAC) Fault Warning Computer (FWC) detects a difference of 200 feet or more between altitude data on the Pilot and Copilot PFDs

Possible Causes:

  • Micro Air-Data Computer (MADC) 1 (A27)
  • Micro Air-Data Computer (MADC) 2 (A28)
  • Micro Air-Data Computer (MADC) 3 (A29)
  • Pitot/Static Probe 1 (MT149)
  • Pitot/Static Probe 2 (MT152)
  • Pitot/Static Probe 3 (MT150)
  • Standby/Pitot Static Probe (MT151)
  • Stall Protection Computer (SPC) (A40)

Troubleshooting Tips:

Advisory Wire/Service Bulletin:

  • AW 700-34-0346 - Air Data Computer (ADC) and Pitot-Static Probes - Altitude Split and Troubleshooting Guidance

Forum Articles/Infoservice/Newsletter:

Altitude split up to 200 feet in flight may be acceptable. As the altitude split value varies between one aircraft to an other, it is important that operators/flight crews are familiar with the particular altitude split characteristic values between the different altimetry systems of their aircraft.

Slow split increases over a certain period of time (months) from particular altitude split characteristic values is a normal condition attributed to the different drift characteristics between ADCs and Pitot/Static probe deterioration over time.

For this reason, per the TLMC Part 2 section 5-10-13 (RVSM qualified aircraft), the ADCs are tested at regular interval and the Pitot/Static probes have a life limit.

However altitude split that significantly increases from particular altitude split characteristic values over a short period of time (same flight leg or from one flight leg to the next) or reaching 200 feet associated with the amber ALT miscompare annunciation should be investigated.

In any case this new altitude split value should be compared with the normally acceptable altitude split characteristic values on similar flight profiles (speed, altitude, weight, flight phase).

It is recommended that the flight crew debrief includes the following prior to initiate any troubleshooting.

Debrief Info:

  • Altitude at which the condition/split occurs
  • PFD 1 and PFD 2 altitude value and barometric setting values
  • Value of split
  • Duration of the condition
  • ALT and or CAS posted
  • Standby Altimeter (ISI) value
  • If possible flight crew evaluation on which side is incorrect (pilot/copilot)

The above may help to focus on a single side as necessary or for future assistance by Bombardier Customer Response Center (BA CRC).

Quick Links:

Operational Test of the Air-Data Computer System AMM 34-11-00-710-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Functional Test of the Air Data Computer,
(RVSM Qualified A/C)		 AMM 34-11-00-720-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Functional Test of the Pitot-Static Systems AMM 34-11-00-720-802 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Static Source Error Correction (SSEC)
Corrected Altitude Check of the Air-Data
Computer (ADC) System		 AMM 34-11-00-750-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Leak Test of the Pitot-Static System 1 AMM 34-11-00-790-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Leak Test of the Pitot-Static System 2 AMM 34-11-00-790-802 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Leak Test of the Pitot-Static System 3 AMM 34-11-00-790-803 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Leak Test of the Standby Pitot-Static System AMM 34-11-00-790-804 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Removal of the Pitot-Static Probes AMM 34-11-01-000-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Installation of the Pitot-Static Probes AMM 34-11-01-400-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Alignment Check of the Pitot Static Probes AMM 34-11-01-820-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Detailed Inspection of the Pitot-Static Probes AMM 34-11-01-220-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
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 ]
Cleaning of the Pitot-Static Probes AMM 34-11-01-160-801 [ 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 ]
Write Pilot-Event Marker to Memory AMM 45-45-00-970-819 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Access to Non-Volatile Memory (NVM) Management AMM 45-45-00-970-822 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Inspection of Pitot-Static Probes CMM 34-10-68 [ Global Express ]  [ G5000 ]  [ Global XRS ]

Troubleshooting Recommendations:

  1. Check if the ADC 3 FAIL or ADC 3 MISCMP (Miscompare) CAS messages are present.

    1. If ADC 3 FAIL or ADC 3 MISCMP (Miscompare) CAS messages are present, as part of the continuous NFF monitoring, Bombardier identified a trend associated with ADC3 FAIL and ADC3 MISCMP (Mis-compare) CAS. To provide additional troubleshooting information and collect data on those events, to better understand the situation, please use and complete the new Troubleshooting Checklist when an ADC 3 FAIL or ADC 3 MISCMP occurs. The Troubleshooting Checklist provides guidelines for in-flight procedures, additional troubleshooting and a flight test data sheet to be completed.
    2. For any other fault scenario (No ADC 3 FAIL or ADC 3 MISCOMP CAS messages present), continue with next step.

  2. Correct any stall system or SPC fault CAS message issues before troubleshooting this fault.
  3. Perform the visual inspection of the RVSM critical area (zone 4). Make sure that the steps and gaps of the forward equipment compartment doors, forward hydraulic bay door, oxygen service door, RAT door and radome are within the tolerances (SRM 51-14-04). Make sure that the pitot-static probes sealant is smooth.
  4. Perform the detailed inspection of the pitot-static probes (AMM TASK 34-11-01-220-801).
    NOTE: As a general guidance for areas outside of braze joints; voids or porosities that have a diameter within <0.040 in. and depth <0.030 in. are acceptable, given that the bottom is detectable under 3X magnification. Refer to AMM Task 34-11-01-220-801 and CMM 34-10-68 for pictures and criteria per section of the Pitot-Static probe.

    1. If fault remains, repair as required and continue with next step.
    2. If the system checks are good, continue with next step.

  5. Perform the alignment check of the pitot-static probes (AMM TASK 34-11-01-820-801).
    NOTE: Record the angular value for all four probes using the Pitot Probe Alignment Table. If a probe is removed for cleaning or replaced, the installation of the probe has to be done at the same angle.

    1. If fault remains, repair as required and continue with next step.
    2. If the system checks are good, continue with next step.

  6. Perform the cleaning of the pitot-static probes (AMM TASK 34-11-01-160-801).
  7. Perform the contamination removal of the pitot line P1 (AMM TASK 34-11-01-100-801), pitot line P2 (AMM TASK 34-11-01-100-802), pitot line P3 (AMM TASK 34-11-01-100-803), pitot line P STBY (AMM TASK 34-11-01-100-804), static line P1 S1/S2 (AMM TASK 34-11-01-100-805), static line P2 S1/S2 (AMM TASK 34-11-01-100-806), static line P3 S1/S2 (AMM TASK 34-11-01-100-807) and static line P STBY S1/S2 (AMM TASK 34-11-01-100-808).

    1. If there is any contamination, repair as required and continue with next step.
    2. If there is no contamination, continue with next step.

  8. Perform the functional test of the pitot-static system (AMM TASK 34-11-00-720-802).
    NOTE: When performing the leak check after the contamination removal procedure, each system should be tested one at a time, leaving to other system open to ambient pressure, this to detect any inter system issue(i.e. incorrect installation).

    1. If fault remains, repair as required and continue with next step.
    2. If the system checks are good, continue with next step.

  9. Perform the functional test of the air data computer system and record the test data (AMM TASK 34-11-00-720-801).
    NOTE: Do not replace an air data computer that passes the functional test of the air data computer system.

    1. If fault remains, repair as required and continue with next step.
    2. If the system checks are good, continue with next step.

  10. Perform ADC Strapping configuration check (through the PMAT).

    • Start the PMAT
    • Select CAIMS
    • Double click on SYSTEM DIAG
    • Double click on 34-00 NAVIGATION
    • Select MICRO AIR DATA COMPUTER 1, 2 or 3
    • Double click on SELECT
    • Double click on LRU TEST
    • Select CONFIGURATION STATUS
    • Double click on SELECT
    • LOOK for SDI INPUT SDI 3, 2 and 1 (ADC position on the aircraft)
    • LOOK for UNIT ID INPUT ID 6 to 0 (SSEC configuration)

    ADC Strapping for Global Express Series(Express, XRS or 5000)
    ADC 1 SDI INPUT SDI 3 NON ACTIVE (OPEN)
    SDI INPUT SDI 2 NON ACTIVE (OPEN)
    SDI INPUT SDI 1 ACTIVE (GROUND)
    ADC 2 SDI INPUT SDI 3 NON ACTIVE (OPEN)
    SDI INPUT SDI 2 ACTIVE (GROUND)
    SDI INPUT SDI 1 NON ACTIVE (OPEN)
    ADC 3 SDI INPUT SDI 3 ACTIVE (GROUND)
    SDI INPUT SDI 2 NON ACTIVE (OPEN)
    SDI INPUT SDI 1 NON ACTIVE (OPEN)
    ADC 1
    Parameter Express & XRS G5000
    UNIT ID INPUT ID 6 (PIN P1-7) NON ACTIVE NON ACTIVE
    UNIT ID INPUT ID 5 (PIN P1-6) ACTIVE ACTIVE
    UNIT ID INPUT ID 4 (PIN P1-5) NON ACTIVE NON ACTIVE
    UNIT ID INPUT ID 3 (PIN P1-4) ACTIVE NON ACTIVE
    UNIT ID INPUT ID 2 (PIN P1-3) NON ACTIVE ACTIVE
    UNIT ID INPUT ID 1 (PIN P1-2) ACTIVE ACTIVE
    UNIT ID INPUT ID 0 (PIN P1-1) NON ACTIVE ACTIVE
    ADC 2
    Parameter Express & XRS G5000
    UNIT ID INPUT ID 6 (PIN P1-7) NON ACTIVE NON ACTIVE
    UNIT ID INPUT ID 5 (PIN P1-6) ACTIVE ACTIVE
    UNIT ID INPUT ID 4 (PIN P1-5) NON ACTIVE NON ACTIVE
    UNIT ID INPUT ID 3 (PIN P1-4) ACTIVE NON ACTIVE
    UNIT ID INPUT ID 2 (PIN P1-3) NON ACTIVE ACTIVE
    UNIT ID INPUT ID 1 (PIN P1-2) ACTIVE ACTIVE
    UNIT ID INPUT ID 0 (PIN P1-1) NON ACTIVE ACTIVE
    ADC 3
    Parameter Express & XRS G5000
    UNIT ID INPUT ID 6 (PIN P1-7) NON ACTIVE NON ACTIVE
    UNIT ID INPUT ID 5 (PIN P1-6) ACTIVE ACTIVE
    UNIT ID INPUT ID 4 (PIN P1-5) NON ACTIVE NON ACTIVE
    UNIT ID INPUT ID 3 (PIN P1-4) ACTIVE NON ACTIVE
    UNIT ID INPUT ID 2 (PIN P1-3) NON ACTIVE ACTIVE
    UNIT ID INPUT ID 1 (PIN P1-2) ACTIVE ACTIVE
    UNIT ID INPUT ID 0 (PIN P1-1) NON ACTIVE ACTIVE

  11. At the next flight, select the appropriate Flight Test FTP check table per platform (below) and record the data in it.

    • Global Express Flight Test FTP check
    • Global 5000 & Global 5000 GVFD Flight Test FTP check
    • Global Express XRS & Global 6000 Flight Test FTP check
      Every time a reading (row) is taken, press the pilot event marker (PEM) and record the time (AMM TASK 45-45-00-970-819).
      NOTE: The table is divided into two parts, the first part is used to record the airspeed and the altitude, the second part is used to record the TAT, the miscompare value and the time that the PEM was pressed. Make sure that you fill both parts of the table every time you press the PEM.
      With autopilot engaged (heading and altitude), make sure that the following conditions are met:
    • Auto-throttle to off
    • Altitude stabilized
    • Speed per Flight Test Data Sheet for two minutes

  12. Check if the flight data is satisfactory.

    1. If the flight data is satisfactory, do close out.
    2. If the flight data is unsatisfactory, download the NVM of the stall protection system (SPC Channel A and B) (AMM TASK 45-45-00-970-822).
      NOTE: Contact your FSR or Customer Response Center (BA CRC) for guidance.

  13. Do close out.

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