Which action is NOT part of starting the FADPU?

Activating the main engine is not a part of starting the FADPU (Fluid Analysis Data Processing Unit). The FADPU is a system that often operates independently and is typically powered by hydraulic power units (HPUs). To start the FADPU, one must ensure that the hydraulic power is secured and available, which involves securing power to the HPUs and turning on the FADPU using the designated controls, such as a push button. Additionally, opening the FADPU on each shaft is necessary to allow for proper data collection and operation. However, the main engine's activation typically pertains to operational readiness and is not a direct step in initiating the FADPU itself. Thus, the main engine's activation is unrelated to the specific processes involved in starting the FADPU.