APU & Display Panel

Overview

This panel includes controls and indicators for managing the Auxiliary Power Unit (APU), adjusting the lower Integrated Display Unit (IDU5), and controlling the mobile communication system. It supports essential ground operations and basic diagnostics for the APU, while offering visual adjustments for onboard display units.

Panel Components

APU MASTER SW

This button powers the APU's Electronic Control Unit (ECU), preparing the system for startup.
- When pushed:
  - The ECU energizes.
  - The APU is armed for start-up.
  - The FAULT light may illuminate if an abnormal condition is detected.
- When released:
  - A shutdown command is issued.
  - The ECU either remains powered (for some models) or powers off (for newer configurations).
- In abnormal conditions:
  - The FAULT ON light turns on.
  - Refer to non-normal operation procedures for further action.

APU START Switch

This is a momentary pushbutton used to start the APU.
- When pressed:
  - Sends the start command to the ECU.
  - Triggers the APU start sequence.
These status lights provide feedback about the APU condition:
- AVAIL ON: APU has reached operational speed and is ready to take electrical or pneumatic loads.
- OFF: APU is not operating or has not yet reached usable speed.

Note

ECU start command is triggered by the APU START switch.

LOWER DSPL/CONTRAST Knob

This knob is used to adjust the brightness and contrast of IDU5 (Lower Display Unit).
- Outer ring:
  - Rotate clockwise to increase brightness.
  - Counterclockwise to decrease brightness.
  - When set to OFF, IDU5 is turned off.
- Inner ring:
  - Adjusts the contrast of overlay information displayed on IDU5.

MOBILE COM Switch

This switch controls the mobile communication system on board.
- When pushed:
  - Mobile communication is turned off.
- When released:
  - Mobile communication is automatically managed by the system based on operational context, such as flight altitude and airspace regulations.

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