How is rotational vibration typically monitored in a gas turbine engine?

• A. Through thermal imaging cameras mounted on the casing.
• B. With accelerometers on bearing housings or gearboxes, plus periodic trend analysis of vibration data.
• C. By measuring fuel flow fluctuations.
• D. By acoustic emission sensors positioned around the exhaust.

Answer: (B)

Rotational vibration is best tracked by directly sensing the motion of the rotating parts with accelerometers placed on bearing housings or gearboxes. These sensors pick up the dynamic forces caused by imbalance, misalignment, looseness, bearing wear, or gear faults as the shaft spins. By gathering data over time and performing periodic trend analysis, you can see gradual changes in vibration levels or in the frequency content, which reveals evolving faults long before a failure occurs. This approach provides early warning and supports planned maintenance.

Other options miss the mark because they focus on something other than the rotating machinery itself: thermal imaging cameras detect surface temperature, not vibration; measuring fuel flow fluctuations relates to the fuel system, not rotor dynamics; and acoustic emission sensors around the exhaust capture high-frequency noise from combustion or exhaust flow, not the rotational vibration of bearings and gears.