Service crane for a wind turbine

1. A service crane for a wind turbine comprising a nacelle, and a hub, onto which one or more wing blades is attached via a wing pitch bearing, the service crane comprising:

an attachment foundation for connection to the hub, wherein the service crane is adapted to be mounted on the wind turbine during operation and to be dismounted when not being used,

wherein the attachment foundation has a configuration that substantially corresponds to the configuration of the wing pitch bearing such that the attachment foundation is mountable on the hub of the wind turbine via the wing pitch bearing, and

wherein the attachment foundation is connectable with the wing pitch bearing in the same manner as the wing blade is connectable with the wing pitch bearing such that the wing blade must be dismounted from the wing pitch bearing before the attachment foundation of the service crane is mounted to the wing pitch bearing.

2. The service crane according to claim 1 , wherein the attachment foundation is mainly connected to the wing pitch bearing from an outside of the hub.

3. The service crane according to claim 1 , wherein the wing blade is attached to a tower of the wind turbine when dismounted.

4. The service crane according to claim 1 , wherein the attachment foundation has a U-shaped, a horse shoe-shaped, or an at least partly circular configuration.

5. The service crane according to claim 1 , where the wing pitch bearing comprises a fixed part and a turnable part, the turnable part being arranged either on an inside of the fixed part or on an outside of the fixed part, wherein the attachment foundation is connected with the fixed part and/or the turnable part.

6. The service crane according to claim 5 , wherein the turnable part of the wing pitch bearing is adapted to turn the service crane during operation.

7. A wind turbine comprising the service crane according to claim 1 .

8. A method for mounting a service crane on a wind turbine comprising:

dismounting a wing blade from an attachment interface of a wing pitch bearing of a hub, and

mounting an attachment foundation of the service crane on the attachment interface of the wing pitch bearing.

9. The method according to claim 8 , wherein the wing blade after being dismounted is lowered onto the ground or is attached to a tower of the wind turbine.

10. The method according to claim 9 , wherein a nacelle of the wind turbine is yawed away from the wing blade, which has been attached to the tower, before the attachment foundation is connected to the wing pitch bearing.

11. The method according to claim 8 , wherein mounting the attachment foundation further comprises mounting the attachment foundation to a turnable part of the wing pitch bearing.