E. M. Rasselkorde, TWI Validation Centre (Wales), Port Talbot, United Kingdom; M. Papaelias, The University of Birmingham, Birmingham, United Kingdom
Aerospace gas turbine Turbo Fan engines operate under harsh environmental conditions involving high temperatures, friction, eroding and corroding elements. Low Pressure Compressor blades (Fan Blades) are also subject to very high stresses and vibration, especially during aircraft take-off and landing, which can lead to crack initiation and subsequent propagation. Unless existing cracks are identified before reaching critical dimensions, turbine blades will fail causing a chain of events that could eventually render the host turbine engine inoperable. This paper discusses the development of novel eddy current arrays customised for the inspection of turbine blades using a commercially available eddy current acquisition unit.
Summary: Modern turbine Turbo Fan engines incorporate Low Pressure Compressor blades (Fan Blades) which are subject to the highest stresses, vibration, temperatures, friction, corrosion and erosion rates than any other aircraft component, particularly during take-off and landing. There are currently various methods that can be employed to inspect fan blades, such as visual, Fluorescent Particle Inspection (FPI), standard ultrasonic testing (UT), ultrasonic phased arrays, thermography, conventional and digital radiography, shearography and finally, eddy current (EC) testing. Eddy current testing is commonly performed by an experienced operator, using a portable eddy current unit in conjunction with a standard 2 MHz eddy current pencil probe. This method of inspection is a very slow and tiring process, and in several cases defects can be missed either due to operator fatigue or technical limitations of the system employed.
This paper will discuss the development of a novel Eddy Current Array (ECA) for the fast and reliable inspection of compressor blades and the results produced.
