System and method for ground based inspection of wind turbine blades

A method of remotely inspecting blades of a wind turbine in situ, the method comprising:

• capturing one or more images of at least a portion of each wind turbine blade with a thermal imaging camera as each blade passes through a field of view of the thermal imaging camera while the wind turbine is rotating and undergoing cyclic load due to gravity and variations in wind loads and when the blade has substantially reached thermal equilibrium with ambient air after sunset in order to produce thermal imaging data;
• analyzing the thermal imaging data to identify atypical thermal patterns due to thermoelastic heating and/or frictional heating within or around defects within the blades;
• and
• determining at least one dimension of at least one of the defects identified within the blades.