Which of the following is a typical sign of bearing or shaft wear in a turbine?

• A. Lower oil temperature
• B. Increased vibration
• C. Decreased vibration
• D. Higher fuel pressure

Answer: (B)

Bearing or shaft wear shows up as increased vibration because as clearances grow and the rotor loses some stiffness, imbalance and misalignment effects become more pronounced. That extra looseness lets the rotor wobble slightly during rotation, producing higher vibratory amplitudes that are noticeable in normal operation. Over time, this vibration can escalate as wear progresses, signaling a need for inspection or bearing replacement. The other signs aren’t typical indicators of bearing wear: oil temperature tends to vary with cooling and load, not directly with wear; a decrease in vibration would mask a developing fault rather than reveal it; and fuel pressure is governed by the fuel system and engine controls, not by bearing wear.