Failure analysis of Ist stage compressor rotor blades of an aeroengine

Four damaged I stage compressor rotor blades of an aeroengine were forwarded to the laboratory for investigation. All the blades were found damaged due to tip rubbing. The tip of the blades had bent in a direction opposite to the blade rotation direction and there were severe heat effects with dislodgement of material. Fluorescent dye penetrant inspection did not reveal any cracks in any of the blades