START (momentary) –
Positioning the APU switch from OFF to START and
releasing it to ON, initiates an automatic start sequence.
ON – Normal position when the APU is running.
The automatic start sequence begins with the opening of
the air inlet door. When the APU inlet door reaches the full
open position the start sequence begins. After the APU
reaches the proper speed, ignition and fuel are provided.
When the APU is ready to accept a bleed air or electrical
load the APU GEN OFF BUS light illuminates.