A computer implemented method for gas turbine maintenance, comprising: identifying a combustor in need of repair or replacement within a gas turbine; and repairing or replacing the combustor; wherein said identifying comprises calculating base swirl of the gas turbine and calculating relative swirl of the gas turbine in order to associate a gas path from a thermocouple to the combustor in need of repair or replacement, wherein calculating relative swirl comprises calculating the difference between the base swirl and a reference swirl retrieved from a reference database characterized in that the reference swirl is retrieved from a reference database, and wherein the reference swirl is selected on the basis of turbine load, wherein the reference swirl comprises the mean-subtracted exhaust temperature pattern for a plurality of samples; wherein the relative swirl is equal to a cross-correlation shift, wherein the cross-correlation shift is a phase shift that gives the highest correlation coefficient between the base swirl and reference swirl; wherein calculating base swirl comprises calculating (a) unsteady pressure amplitude as a function of angular position within the gas turbine and/or (b) mean-subtracted exhaust temperature as a function of angular position within the gas turbine; preferably wherein calculating base swirl comprises calculating (a) unsteady pressure amplitude as a function of angular position within the gas turbine and (b) mean-subtracted exhaust temperature as a function of angular position within the gas turbine; and wherein a reference database is updated in real time with base swirl data as a function of gas turbine load. identifying a combustor in need of repair or replacement within a gas turbine; and repairing or replacing the combustor; wherein said identifying comprises calculating base swirl of the gas turbine and calculating relative swirl of the gas turbine in order to associate a gas path from a thermocouple to the combustor in need of repair or replacement, wherein calculating relative swirl comprises calculating the difference between the base swirl and a reference swirl retrieved from a reference database characterized in that the reference swirl is retrieved from a reference database, and wherein the reference swirl is selected on the basis of turbine load, wherein the reference swirl comprises the mean-subtracted exhaust temperature pattern for a plurality of samples; wherein the relative swirl is equal to a cross-correlation shift, wherein the cross-correlation shift is a phase shift that gives the highest correlation coefficient between the base swirl and reference swirl; wherein calculating base swirl comprises calculating (a) unsteady pressure amplitude as a function of angular position within the gas turbine and/or (b) mean-subtracted exhaust temperature as a function of angular position within the gas turbine; preferably wherein calculating base swirl comprises calculating (a) unsteady pressure amplitude as a function of angular position within the gas turbine and (b) mean-subtracted exhaust temperature as a function of angular position within the gas turbine; and wherein a reference database is updated in real time with base swirl data as a function of gas turbine load.