Abstract: A tool and method for measuring turbine blade outer shroud notch wear in situ in a turbine having multiple stages of turbine blades, each stage being arranged in a circular array. The tool comprises a longitudinal member having first and second ends. A gauge pin for applying a separating force between two adjacent turbine blades is affixed adjacent the first end. A positioning member is mounted about the longitudinal member intermediate the first and second ends and a driving site is located adjacent the second end. The tool is used by inserting the first end of the longitudinal member through a first outer stage of blades and into the interior of the turbine such that the positioning member abuts the first outer stage of blades to place the gauge pin between two adjacent blades of an interior stage of blades. A torque force is applied to the tool at the driving site to separate the adjacent blades.