a method of manufacturing a filled aerofoil component for a gas turbine engine comprises using a capping panel to cover a pocket in a pocketed aerofoil body . during manufacture , a pre - formed filler insert is provided to support the capping panel in the correct position . this ensures that the outer surface of the capping panel is located as accurately as possible . this means that the capping panel can be made to be as thin as possible , which in turn reduces weight and material wastage . the pre - formed filler insert provides a lightweight core for the finished aerofoil component in use .