Hollow shaft as rotor mast of helicopter has device provided inside cavity of hollow shaft for detecting cracks in shaft and connected to analyzing and indicating unit

摘要

A device(10) is provided inside the cavity of the hollow shaft for detecting cracks in the shaft(1) and is connected to an analyzing and indicating unit(23). The device has at least two sealing means(12,13) for sealing the hollow shaft against atmosphere, and the sealed shaft cavity(19) is overpressurized with gas relative to the outside atmosphere and a gas pressure change in the cavity is sensed by a pressure sensor(22) which sends a signal to the analyzing and indicating unit.