Post FBO windmilling bumper
A bearing arrangement rotatably supports a shaft of an aircraft engine. The bearing arrangement comprises a bearing having rolling elements disposed between inner and outer races. The inner race is affixed to the shaft. A decoupler normally structurally couples the outer race of the bearing to a stator structure of the engine. The decoupler is configured to release the bearing from the stator structure when subject to a predetermined critical load. A bumper is mounted to the stator structure and encircles the bearing. The bumper has a radially inwardly facing surface disposed in close proximity to a radially outer surface of the outer race of the bearing and defines therewith a radial gap to accommodate and constrain an orbiting motion of the rotor about the central axis of the engine after decoupling at the bearing. The bumper further has an axially forwardly facing surface which is axially spaced by a predetermined axial fore gap from a first flange projecting radially outwardly from a front end portion of the outer race of the bearing. The first flange of the outer race is axially trapped between the stator structure and the bumper. After decoupling, the bearing is free to axially and radially move within the radial gap and the axial fore gap.
1. A bearing arrangement for supporting a fan rotor of an aircraft engine, comprising a bearing having rolling elements disposed between inner and outer races, the outer race having first and second axially spaced-apart flanges projecting radially outwardly from axially opposed end portions of the outer race, a bearing support for supporting the bearing on a stator structure of the engine, a decoupler between the bearing and the bearing support, the decoupler being configured to release the bearing from the bearing support when subject to a predetermined critical load, a bumper surrounding the bearing, the bumper being axially disposed between the first and second axially spaced-apart flanges of the outer race, the bumper and the outer race of the bearing defining a radial gap and an axial gap therebetween, the bearing being free to move within said radial and axial gaps when the fan rotor rotates at windmilling speed after decoupling of the bearing from the bearing support, wherein the bearing support has a radially inwardly projecting flange, the first flange of the outer race forming with the radially inwardly projecting flange of the bearing support an inverted flange arrangement, and wherein the decoupler comprises a set of frangible fasteners, the first flange of the outer race being attached to the radially inwardly projecting flange of the bearing support by said frangible fasteners.
2. The bearing arrangement defined in claim 1 , wherein the radial gap is sized to tune the natural frequency of vibration of the fan rotor at higher speeds than the windmilling speed.
3. The bearing arrangement defined in claim 1 , wherein the first flange of the outer race is spaced axially forwardly of a front axially facing surface of the bumper by an axial fore gap.
4. The bearing arrangement defined in claim 3 , wherein the axial fore gap is sized to allow the outer race to move off from a spigot projecting axially rearwardly from the bearing support.
5. The bearing arrangement defined in claim 3 , wherein the second flange of the outer race is axially spaced rearwardly from a corresponding rear abutting surface on the bumper by an axial aft gap.