This invention relates to a blade assembly comprising: a hub which is rotatable about an axis; at least one blade having an aerofoil portion and a root, wherein the root is coupled to the hub using a primary retention device which prevents radial separation of the root and hub in normal use; and, a secondary retention device which comprises an annular catcher having a restriction through which the root portion cannot radially pass, the restriction being located radially outwardly and radially spaced from the root part during use.