A turbofan engine includes a fan and a fan actuation system. The fan has a plurality of fan blades. Each of the plurality of fan blades is rotatable about a pitch axis. The fan actuation system includes one or more actuators for rotating the plurality of fan blades about the pitch axis and one or more thrust bearings. The fan actuation system is characterized by a fan actuation system envelope in a range of 300 to 1860. The fan actuation system envelope is given by

[00001]$\frac{N_{\mathrm{FB}}{D}_{\mathrm{FT}}{M}_{\mathrm{cruise}}}{\left(\frac{R_{\mathrm{TB}}}{N_{\mathrm{FB}}}\right)},$

where N.sub.FB is a number of the plurality of fan blades, D.sub.FT is a fan tip diameter of the plurality of fan blades, M.sub.cruise is a Mach number of the turbofan engine at cruise operating conditions, and R.sub.TB is a thrust bearing radius of the one or more thrust bearings.

A wind turbine nacelle includes a rotor generator shaft, a rotor connected to the rotor generator shaft, an array of permanent magnets mounted on a circular outer surface of the rotor, a rotor hub directly connected to a forward end of the rotor generator shaft, a plurality of circumferentially spaced blades mounted on the rotor hub to face upwind, a stator ring surrounding the rotor, a plurality of encased coils mounted on an inner surface of the stator ring facing and radially spaced from the array of permanent magnets, a rear chassis attached to a rear surface of the stator ring and having a rear bearing housing, a rear bearing mounted in the rear bearing housing, a forward chassis attached to a front surface of the stator ring and having a front bearing housing, and a front bearing mounted in the front bearing housing.

A system for a wind turbine nacelle having a shaft housing, a blade shaft that extends through the shaft housing and is rotatable relative to the shaft housing, a blade holder connected to the blade shaft, and an outer bearing between the blade shaft and the shaft housing includes a conical spring. The conical spring engages a portion of the outer bearing to exert a preload force on the outer bearing. The system further includes a backstop surrounding the blade shaft and having an interference fit with the blade shaft and a pin extending through the blade shaft and the blade holder. The pin is positioned to prevent the blade shaft from moving relative to the backstop.

The invention provides for controlling a wind turbine comprising pitch-adjustable rotor blades. The invention involves determining, based on detected wind conditions, wind turbine control parameters for controlling the wind turbine in accordance with a defined wind turbine control strategy, where the control parameters include a reference pitch angle for the rotor blades. The invention involves obtaining bearing control parameters each indicative of a parameter for controlling pitch bearings of the wind turbine that is for adjusting pitch of the rotor blades. The invention involves determining whether a defined set of operational parameters of the wind turbine, including the bearing control parameters, in combination correspond to a combination of operational parameters defined to be indicative of a level of wear above a threshold wear level. The pitch bearings are then controlled based on the reference pitch angle and on the threshold determination.

A repair device is provided for a wind turbine having a bearing with damaged teeth driven by a motor. The repair device includes a carrier for connection to the bearing and radially aligned with the damaged teeth. A gear train is mounted on the carrier for creating a torque transfer path from the motor to non-damaged teeth of the bearing.

A turbofan engine for an aircraft includes a fan and a fan actuation system. The fan has a plurality of fan blades coupled to a fan shaft having one or more fan bearings. The fan blades are rotatable about a pitch axis. The fan actuation system is disposed within a fan hub and includes one or more actuators for rotating the fan blades about the pitch axis and one or more radial thrust bearings. The fan actuation system is characterized by a fan actuation system length envelope in a range of 8.5 to 24 and given by $\frac{N_{\mathrm{FB}}{D}_{\mathrm{FT}}}{L_{\mathrm{AXIAL}}\left(\frac{R_{\mathrm{TB}}}{N_{\mathrm{FB}}}\right)}.$
N.sub.FB is a number of the fan blades, D.sub.FT is a fan tip diameter of the fan blades, R.sub.TB is a thrust bearing radius of the radial thrust bearings, and L.sub.AXIAL is an axial length from a fan hub tip to the fan bearings.

A first aspect of the invention provides a pitch controlled wind turbine comprising a tower, a nacelle mounted on the tower, a hub mounted rotatably on the nacelle, and at least three wind turbine blades, wherein each wind turbine blade extends between a root end connected to the hub via a pitch mechanism, and a tip end, the wind turbine further comprising at least three blade connecting members, each blade comprising a first connection point and a second connection point, wherein each blade connecting member extends from a first connection point on one wind turbine blade towards a second connection point on a neighbouring wind turbine blade, where each connection point on a given wind turbine blade is arranged at a distance from the root end and at a distance from the tip end of the wind turbine blade and adjacent a leading edge of the wind turbine blade, and wherein each connecting member is independently moveable in two orthogonal directions at the respective first and second connection points to which it attaches.

A pitch tube for a blade pitch control system of a wind turbine includes a tube body extending from a first axial end to a second axial end, for passing supply lines through a transmission. The tube body is designed in multiple parts and made of a non-conductive material only in an axial partial region in order to electrically insulate the first axial end in relation to the second axial end and/or in order to electrically insulate the tube body in relation to the transmission.

A turbofan engine for an aircraft includes a fan and a fan actuation system. The fan has a plurality of fan blades coupled to a fan shaft having one or more fan bearings. The fan blades are rotatable about a pitch axis. The fan actuation system is disposed within a fan hub and includes one or more actuators for rotating the fan blades about the pitch axis and one or more radial thrust bearings. The fan actuation system is characterized by a fan actuation system length envelope in a range of 8.5 to 24 and given by

[00001]$\frac{N_{\mathrm{FB}}{D}_{\mathrm{FT}}}{L_{\mathrm{AXIAL}}\left(\frac{R_{\mathrm{TB}}}{N_{\mathrm{FB}}}\right)}.$

N.sub.FB is a number of the fan blades, D.sub.FT is a fan tip diameter of the fan blades, R.sub.TB is a thrust bearing radius of the radial thrust bearings, and L.sub.AXIAL is an axial length from a fan hub tip to the fan bearings.

A pitch tube for a blade pitch control system of a wind turbine includes a tube body extending from a first axial end to a second axial end, for passing supply lines through a transmission. The tube body is designed in multiple parts and made of a non-conductive material only in an axial partial region in order to electrically insulate the first axial end in relation to the second axial end and/or in order to electrically insulate the tube body in relation to the transmission.