Method of fastening a joining insert to a wind turbine rotor blade element

A method of fastening a joining insert to a wind turbine rotor blade element, the method comprising:

• providing the wind turbine rotor blade element of a fiber-reinforced composite material, the wind turbine rotor blade element having a joining surface and defining a blind hole, the blind hole having a proximal end at the joining surface and a distal end within the fiber-reinforced composite material;
• forming at least one channel through the fiber-reinforced composite material, the at least one channel connecting the distal end of the blind hole to a channel opening at least at one of an inner surface and an outer surface of the wind turbine rotor blade element;
• placing the joining insert in the blind hole;
• filling a space between the joining insert and the blind hole with a liquid plastics material in a vacuum infusion process, wherein the channel opening is connected either to a liquid plastics material supply line or to a process suction line;
• and,
• curing the liquid plastics material.