Method of inspecting the fan track liner of a gas turbine engine

A method of inspecting a fan track liner of a gas turbine engine of a type having a rotatable propulsive fan circumscribed by the fan track liner and having a plurality of fan blades extending radially outwardly from a central hub, the method comprising the steps of:

• affixing at least part of an inspecting device to the fan so as to be directed towards the fan track liner;
• and
• rotating the fan within the fan track liner to move said at least part of the inspecting device circumferentially relative to at least a region of the fan track liner to thereby scan said region of the fan track liner with said at least part of the inspecting device, wherein
• said inspecting device comprises an ultrasonic transducer which is affixed to said fan,
• said ultrasonic transducer is provided within an assembly which, when affixed to said fan, is supported in sliding contact with a radially innermost surface of the fan track liner during the or each said step of rotating the fan, and
• said assembly comprises an ultrasonic couplant material arranged between the ultrasonic transducer and the fan track liner and for sliding contact with the fan track liner during the or each said step of rotating the fan to facilitate transmission of ultrasonic energy from the ultrasonic transducer into the fan track liner,
• said step of affixing at least part of the inspecting device to the fan involves positioning said at least part of the inspecting device adjacent the fan track liner, such that said step of rotating the fan is effective to move said at least part of the inspecting device across a radially innermost surface of the fan track liner, and
• wherein said method further comprises a step of directing an ultrasonic couplant liquid between the ultrasonic transducer and the fan track liner during the or said each step of rotating the fan.