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Maintenance Control Panel

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Maintenance Control Panel

Overview

The Maintenance Control Panel provides tools for interacting with the flight recorder system and specific maintenance functionalities. These controls support diagnostic testing, data playback, conditional erasure, system power, and environment system verification while the aircraft is on the ground.

Panel Components

Headphone Jack

  • Connect a headset to listen to recorded cockpit voice data.
  • Playback depends on the selected EAFR (FWD or AFT).
  • During a test, a tone plays for approximately 3 to 5 seconds.

FWD/AFT Selection Knob

  • FWD: Plays back cockpit audio from the forward EAFR, including its pre-flight test tone.
  • AFT: Plays back audio from the aft EAFR and its corresponding test tone.

Use this to verify audio channel functionality for each recording unit.

Test Button

  • A momentary button used to start the pre-flight voice channel test and self-test of both EAFRs.

  • If either the FWD or AFT EAFR fails:

    • The corresponding INFO messages will appear on the system:
      • 31 FWD CVR, 31 FWD FDR
      • 31 AFT CVR, 31 AFT FDR

Erase Button

  • A momentary pushbutton used to erase cockpit voice recordings from both EAFRs.

  • Only functions when:

    • Aircraft is on the ground
    • Oil pressure is below 15 psi
    • Parking brake is released
    • Button is held for 2 to 5 seconds

  • Displays the following EICAS messages:

    • During: CVR ERASING
    • After: FWD CVR ERASED, AFT CVR ERASED

Important

Erasing is disabled during flight for safety and compliance.

FCS MAINT Switch

  • OFF: Prevents any manual maintenance tests from being performed.

  • MAINT: Allows manual tests but only under specific ground speed conditions.

    • Conditions are satisfied when:

      • Aircraft is on the ground and the speed remains at or below 60 kt, or
      • Speed is below 30 kt after decelerating from above 60 kt

FADEC MAINT POWER Switch

  • Includes L and R switches for the left and right engine FADEC systems.

  • When pressed:

    • Supplies 28 V DC power to the selected FADEC system

  • When released:

    • Power is disconnected; FADEC returns to unpowered state

Used for ground diagnostics without starting the engines.

Battery Voltage Display

  • Digital display shows the voltage level of the selected battery.
  • Output depends on the BATTERY CHECK selector setting.

BATTERY CHECK Selector

  • Allows voltage display for different battery sources:

    • MAIN: Displays main battery voltage
    • OFF: Turns off the display
    • APU: Displays APU battery voltage

Useful for checking battery health during maintenance.

BATT PWR Switch

  • NORM: Keeps battery direct buses powered during normal operations.

  • ELEC MAINT: Activates maintenance mode:

    • Main battery powers:

      • MAIN BATT DIR BUS
      • DC ESS XFER BUS

    • APU battery powers:

      • APU BATT DIR BUS

    • Aircraft enters ground servicing electrical mode

Warning

ELEC MAINT mode is for ground service only. Never use it during flight.

PASS OXY RESET TMR Switch

  • A momentary switch used by ground personnel to reset the passenger oxygen deployment system.

  • Normal status: Switch is unlit and inactive.

  • Press to reset: Executes reset sequence for the oxygen mask deployment timer.

    • If reset is successful:

      • PASS OXY SYS ON light turns off
      • EICAS PASS OXY ON message disappears

  • FAULT ON: Indicates failure of the system timer.

RAT TEST Switch

  • Press and hold for 2 seconds to start the RAT built-in test.

  • During test:

    • Amber L WDW HEAT FAULT and R WDW HEAT FAULT messages appear

    • If successful:

      • RAT TEST ON displays on EICAS for 20 seconds

    • If failed:

      • 24 RAT SYSTEM and/or 24 RAT HEATER messages display on INFO page

WINDOW HEAT TEST Switch

  • Momentary switch that triggers a built-in test of the window heat system.
  • Push to initiate and verify operation through EICAS feedback.

ICE DET TEST Switch

  • Momentary switch to perform a built-in test of the ice detection system.

  • EICAS messages vary depending on anti-ice selector positions:

    • If WING and ENG ANTI-ICE are ON:

      • ICE CONDITION and ICE DETECTION FAULT (cyan) appear for < 7 seconds

    • If any anti-ice selectors are OFF:

      • ICE DETECTED (amber) and ICE DETECTION FAULT (cyan) appear for < 7 seconds

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