A method of machining and inspecting a machine component, comprising: maintaining a repeatable flow rate and/or pressure of a gas through the machine component; drilling a hole within the machine component; determining whether a change in the flow rate and/or the pressure has been detected, and if a change in the flow rate and/or the pressure has not been detected carrying out a further drilling step; and if a change in the flow rate and/or the pressure has been detected: flowing the gas at a first temperature in a cold air line, and then at a second temperature in a hot air line which includes a heater, through the machine component by way of an internal plenum in communication with the cold air line and the hot air line; imaging the hole within the machine component by means of an imager; determining a thermal response by interrogating a derivative of one or more intensity or temperature values captured by the imager due to a transient condition produced by turning off the heater in the hot air line while cold shop air is sent to the plenum via the cold air line; and determining if the thermal response of the hole within the machine component meets a predetermined range of values; and if the thermal response does not meet the predetermined range of values carrying out a further drilling step. maintaining a repeatable flow rate and/or pressure of a gas through the machine component; drilling a hole within the machine component; determining whether a change in the flow rate and/or the pressure has been detected, and if a change in the flow rate and/or the pressure has not been detected carrying out a further drilling step; and if a change in the flow rate and/or the pressure has been detected: flowing the gas at a first temperature in a cold air line, and then at a second temperature in a hot air line which includes a heater, through the machine component by way of an internal plenum in communication with the cold air line and the hot air line; imaging the hole within the machine component by means of an imager; determining a thermal response by interrogating a derivative of one or more intensity or temperature values captured by the imager due to a transient condition produced by turning off the heater in the hot air line while cold shop air is sent to the plenum via the cold air line; and determining if the thermal response of the hole within the machine component meets a predetermined range of values; and if the thermal response does not meet the predetermined range of values carrying out a further drilling step. flowing the gas at a first temperature in a cold air line, and then at a second temperature in a hot air line which includes a heater, through the machine component by way of an internal plenum in communication with the cold air line and the hot air line; imaging the hole within the machine component by means of an imager; determining a thermal response by interrogating a derivative of one or more intensity or temperature values captured by the imager due to a transient condition produced by turning off the heater in the hot air line while cold shop air is sent to the plenum via the cold air line; and determining if the thermal response of the hole within the machine component meets a predetermined range of values; and if the thermal response does not meet the predetermined range of values carrying out a further drilling step.