Method for repairing an abradable coating of a compressor of a gas turbine

A method for repairing an abradable coating of a compressor of a gas turbine, comprising:

• performing at least one chosen from conducting an analysis and selecting an area of the abradable coating to be repaired with a borescope while the gas turbine is still installed in an operating position,
• passing a tool through at least one borescope aperture of the gas turbine to the area of the abradable coating to be repaired and at least partially removing the worn abradable coating,
• extracting the removed worn abradable coating,
• performing at least one chosen from cleaning and preparing the area of the abradable coating to be repaired for application of a repair medium that is hardenable,
• providing that the at least one borescope aperture has an aperture central axis and that the at least one borescope aperture engages an exterior surface of the tool to prevent movement of the tool in a direction perpendicular to the aperture central axis while permitting rotation of the tool around the aperture central axis;
• applying the repair medium to the area to be repaired with an airbrush including a nozzle having a nozzle center axis fixed at an angle to a longitudinal axis of the tool, the nozzle supplying a jet of air and repair medium along the nozzle center axis at the fixed angle to the longitudinal axis such that a direction of the jet with respect to the gas turbine is selectively altered and controlled by rotating the tool around the longitudinal axis, thereby increasing an area covered by the jet with respect to the gas turbine by the rotating the tool around the longitudinal axis;
• providing that the area of the abradable coating to be repaired is on a rotor of the gas turbine and rotating the rotor of the gas turbine to generate a relative circumferential movement between the tool and the area of the abradable coating to be repaired to apply the repair medium;
• hardening the repair medium;
• wherein the repair medium is a mixture of aluminum oxide and a thinner.