APU to Pack on the ER and LR :-----
APU TO PACK TAKEOFF
Before engine start, selecting APU from the FMC scratch pad to the SEL-APU field on the THRUST LIMIT PAGE arms the system for APU to pack takeoff. Approximately one minute after starting the second engine, the bleed air supply system configures for APU to pack takeoff.
When APU is selected to the SEL-APU field after both engines are operating but before takeoff, the bleed air supply immediately configures for APU to pack takeoff.
In APU to pack takeoff configuration:
• the left engine bleed valve is closed,
• the L ENG OFF light is illuminated and remains illuminated,
• the APU provides air to air demand pump C1 and the left pack,
• the center bleed isolation valve is closed,
• the right engine provides air to air demand pump C2,
• the right pack valve is closed, and
• the R PACK OFF light is illuminated and remains illuminated.
The system reconfigures from APU to pack takeoff to normal operation when:
• thrust is reduced to climb thrust, or
• approximately 10 minutes after takeoff, or
• the airplane is above 11,400 feet altitude, or
• APU to pack configuration cannot be continued because of failures in other systems, or
• APU to pack mode is deleted manually