Airbus A340 Series, Brochure

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STL 472.502/90 Issue 6
A340 Auxiliary Power Unit
9.2
General principles
System display
• On ground , the APU renders the aircraft independent
by:
- Providing bleed air for starting engines and for the air
conditioning system,
- Providing electrical power to supply the electrical
system.
• In flight , provision of back-up power for the electrical
system, the air conditioning system and for engine start.
• The APU can be started either by using the aircraft
battery, external power, or normal aircraft supply.
The normal flight envelope does not impose any
limitations for starting, except when batteries are
supplying starting power.
• The APU is controlled by the Electronic Control Box
(ECB) which acts as a FADEC for monitoring start and
shut-down sequences, bleed air and speed/temperature
regulation.
• Controls and displays are located :
- On the overhead panel for APU normal operation
and fire protection,
- On the ECAM for APU parameter display,
- On the external power control panel, next to the nose
landing gear,
- On the REFUEL/DEFUEL panel for APU shut-down.