1. A method comprising: disposing a solid particle detection sensor in a working fluid flow of a gas turbine engine; communicating data from the solid particle detection sensor to a processor; using the processor to perform the following steps; continuously obtaining flow values of solid particles from the working fluid flow; comparing the solid particle flow values to a predetermined upper limit for a given engine operating condition; recognizing a required action in response to the comparison; and continuously obtaining the solid particle flow value values from a cooling fluid flow diverted from a compressor of the gas turbine engine; continuously sensing solid particle flow values at a plurality of locations along the cooling fluid flow; and diagnosing a location of a source of solid particles by evaluating the respective solid particle flow values.