Why is it important to lock the main propulsion shaft before certain operations?

Locking the main propulsion shaft is crucial primarily for safety reasons. This action ensures that the shaft cannot move unexpectedly while maintenance or repairs are being performed, preventing accidents that could lead to injuries. When the shaft is secured, operators can safely work on or near moving parts without the risk of starting the propulsion system unintentionally. This practice minimizes the risk of contact with moving equipment, which could have severe consequences.

In addition to enhancing safety during maintenance operations, it also promotes a controlled environment where technical personnel can diagnose issues or make adjustments without the hazard of rotating machinery. While other factors such as maintenance convenience and contamination reduction may play roles in the operation's overall effectiveness, the paramount importance of safety cannot be overstated.