Annulus filler for gas turbine engine rotor disc

An annulus filler (interblade platform) for bridging the gap between two adjacent blades, eg fan blades, attached to the rotor disc 51 of a gas turbine engine has a body portion 52, eg of composite material, with a lid portion 53 defining an airflow surface for air being drawn through the engine. A front attachment formation 55 connects a forward end of the body portion 52 to the rotor disc 51 and allows rotational movement of the body portion thereabout. The front attachment formation 55 may be pivotal, as shown, or may be rigid (fig.7), the body portion being flexible. A rear attachment formation 56 which connects the rearward end of the body portion 52 to the rotor disc 51 comprises a spring element 56a which expands, eg by 0.1% of the radius of the rotor disc, under operational centrifugal loading such that the rearward end of the body portion moves radially outwardly with the body portion rotating about the front attachment formation. The spring element 56a may be a V-shaped, C-shaped or Ω-shaped spring. The rear attachment formation 56 may include an expansion limiter.