Copyright D.P. Browne 2011

Auxiliary Power Unit (APU)

The APU is situated in the un-pressurized tail cone section. It can generate electrical power for the entire aircraft and provide bleed air for the cabin and for engine start.

The APU controls are on the front of the overhead panel in the middle of the light switches.

Bleed air is available to the aircraft via the APU bleed air button on the pneumatics overhead panel.

AC electrical power is available to the aircraft via the APU generator button on the electrical overhead panel

Starting

The APU start controls are located on the overhead panel at the front in between the light switches. The control panel consists of an APU Master button and an APU start push button.

First, press the APU master button in. This will illuminate the ON/R light in blue.

The APU can be started on APU battery, using external power or using the aircraft electrical power.

Next push in the momentary APU start button which will illuminate the ON light indicating that the APU is starting.

If there is already external power to the aircraft the system display will show the APU system page.

There will be a delay of some seconds for the APU flap to open before the APU N1 begins to increase.

When the APU is running ( APU N1 > 95%) the AVAIL light is illuminated and the ON light extinguished.

The APU is now ready to supply the aircraft with electrical power.

On the electrical overhead panel press in the APU generator push button. All the displays will now function and the APU AVAIL indication will be shown on the EWD.

Control of the APU is automatic

Next