For a bleeds closed takeoff, what must be engaged if the APU is inoperative?

In scenarios where the APU is inoperative during a bleeds closed takeoff, it is essential to have the APU either turned on or confirmed to be unpressurized. The APU, or Auxiliary Power Unit, plays a crucial role in supplying pneumatic pressure to start the engines and can also provide electrical power. However, in a bleeds closed takeoff configuration, the aircraft relies on sufficient pneumatic pressure for engine start without utilizing bleed air from the engines.

When the APU is not operational, confirming it is unpressurized helps identify that the aircraft will rely entirely on the engine's capability to generate thrust and any available pneumatic needs through the normal operation of the engines. Ensuring the APU is in an appropriate state allows for compliance with the requirements necessary for a successful and safe takeoff under these specific conditions. Understanding the operations of the APU and its implications during different takeoff scenarios is crucial for safe flight operations.