Final answer:
The battery switch must be on during all APU ops, including the 10 sec cool down cycle following shutdown.
Step-by-step explanation:
The battery switch must be on during all APU ops, including the 10 sec cool down cycle following shutdown.
The APU can be started utilizing only the aircraft battery(s) and, once running, will provide electrical power to aircraft systems as well as bleed air for air conditioning and for engine start.
Turning on the APU master switch without pressing the start button triggers the following actions: APU is electrically powered and the ECB performs a self-test. APU air intake flap opens. APU fuel valve opens.
The APU can be started at any altitude using normal aircraft electrical power. The APU can be started at any altitude using normal aircraft electrical power. The APU can be started up to 35,000 feet using only the aircraft batteries. The APU can be started up to 35,000 feet using only the aircraft batteries.