Abstract: A probe mechanism for three-dimensional investigation of conditions in a fluid flow such as exists in a turbo-machine. A sensing head having five sensing orifices therein is mounted on a movable probe finger. The probe finger is interchangeable and streamlined to permit measurement of conditions with minimum flow interference. A movable probe shaft supports the probe finger. The probe finger is movable in a radial, a circumferential, and a polar direction. In addition, a dual eccentric drive permits the probe shaft to be relocated and positioned accurately at any point within a predetermined area. Since the sensing head can be completely aligned with the fluid flow vector, calibration efforts are greatly reduced.