Which step follows securing power to HPUs when starting the FADPU?

Securing power to Hydraulic Power Units (HPUs) is a crucial initial step in ensuring that the entire system is ready for operation. Following this, opening the Flight Active Drive Power Unit (FADPU) on each shaft is essential for establishing the necessary connection and allowing the system to function correctly. This step typically involves disengaging the locks or securing mechanisms that hold the FADPU in a standby position. By opening the FADPU on each shaft, you enable hydraulic fluid to flow, which is necessary for the system to begin its operation.

This sequence ensures that all subsequent actions, such as turning on the FADPU and checking the operation of the system, are performed under optimal conditions and that the hydraulic system is fully prepared to support its functions. This careful progression minimizes the risk of system failure or accidents during the start-up procedure.