RR Allison T56/501 engines have 18 thermocouples (3 per combustion liner). Any 1 thermocouple failing can cause a loss of up 24°C TIT at take off power. Not a lot you say - probably true, but the TD system will then increase fuel flow, i.e. increase TIT, until TIT signal from thermocouples matches input from the coordinator: result turbine overtemp, and eventual burn-out of turbine.