Reliable thermosonic inspection of aero engine turbine blades

The application of Thermosonics as a screening technique for identifying cracked aero engine turbine blades is described. Thermosonics is a rapid and potentially, a cost-saving non-destructive testing (NDT) technique for rejecting cracked turbine blades as part of the regular inspection cycle. However, there remains a question over the reliability of the Thermosonic approach. The aim of this work is to assess the reliability of Thermosonics as a screening method for cracks in turbine blades. This work involved the use of 60 turbine blades with known cracks. First, a repeatability study was conducted on a subset of the 60 blades to establish a robust and repeatable experimental procedure, after which all 60 blades were inspected. Results from this work showed the experimental process to be robust and also that the known cracks in 52 out of the 60 blades were detected.