Method for assembling a blade of a wind turbine

Method for assembling a blade of a wind turbine, the wind turbine comprising a tower having a tower surface and resting on a base, a nacelle mounted atop the tower, a hub rotatably attached to the nacelle, the hub comprising a hub connection flange adapted to be detachably connected to a blade connection flange of a rotor blade, the method comprising the next steps:

• fixing a first positioning element in the nacelle or in the top of the tower,
• fixing a second positioning element to the blade in a root blade area,
• lifting the blade to the vicinity of the hub connection flange by means of lifting means,
• putting into contact the first and the second positioning elements;
• providing an accurate position of the blade connection flange, prior to the connection to the hub connection flange, by cooperation of the first and second positioning elements;
• and
• providing, when the first and the second positioning elements cooperate, a trajectory of the blade which is parallel to the axis of a hub connection hole, disposed in the hub connection flange, the provision of the trajectory being carried out by means of a guiding element joined to either the first positioning element, the second positioning element, or both.