Question 581Steam Plants - Assistant Engineer

The correct answer is D) taking rotor position indicator readings. Excessive thrust bearing wear in a main propulsion turbine rotor will first become apparent by taking rotor position indicator readings. These readings can detect even small changes in the rotor's axial position, which is a key indicator of thrust bearing wear. This allows for early detection and proactive maintenance before more severe vibration or other issues arise. The other options are incorrect because they represent later-stage symptoms of bearing wear, rather than the initial indications that would be detected through position indicator readings. Metal particles in the lube oil, rubbing noises, and intermittent vibration would all occur after the thrust bearing has experienced significant wear and degradation.