Patent attributes
A gyroscopic roll stabilizer includes an enclosure, a flywheel assembly, and a motor. The enclosure is mounted to a gimbal for rotation about a gimbal axis and configured to maintain a below-ambient pressure. The flywheel assembly is rotatably mounted inside the enclosure for rotation about a flywheel axis. The flywheel assembly includes a flywheel and flywheel shaft. The flywheel shaft has a first end and an opposite second end; a first cavity formed in the first end and facing away from the second end; and a second cavity formed in the second end and facing away from the first end. The flywheel shaft has a longitudinal passage connecting the first cavity and the second cavity. This longitudinal passage may be used for inspection of one of the cavities and/or an associated seal, from the direction of the other cavity. Related methods are also disclosed.