US Patent 11572804 Systems and methods for internal spline lubrication

A gas turbine engine, has: a shaft rotatable about a central axis and engaged at an end thereof to a rotatable load via a spline; a reference tube circumferentially extending around the shaft, the reference tube secured at a first end to the shaft for rotation therewith and a second end free relative to the shaft for measuring a deformation of the shaft, the reference tube defining at least one tube aperture therethrough; an oil nozzle fluidly connected to a source of lubricant, the oil nozzle defining an exit flow axis intersecting the at least one tube aperture for injecting oil through the reference tube, the shaft defining at least one shaft aperture extending therethrough, the oil nozzle aligned with the spline via the at least one tube aperture and the at least one shaft aperture.