Cross-Turbine Comparison Exposes Faulty Gearbox Cooling Valve
"When the OEM attributed abnormal temperatures to model differences, cross-turbine comparison revealed the real culprit—a faulty thermal bypass valve that standard checks had missed."
The Impact
The Issue
Irregular behavior was detected in the gearbox oil pressure and temperature patterns. The possible causes included oil contamination, filter clogging in the cooling system, malfunctioning thermal bypass valve, radiator contamination, or oil filter blockage.
The Action
At first, the OEM confirmed that differences in gearbox models explained the varying set values between turbines, so no intervention was made. However, continued monitoring showed no recovery, and the upward trend persisted. The service team later replaced the filter, but the irregular pattern remained. In subsequent checks, a temperature gap between turbines with the same gearbox model prompted deeper investigation. During the following maintenance, the thermal bypass valve was replaced with a new one that activates at a lower temperature. The readings immediately stabilized, confirming the source of the problem.