Abstract: Apparatus for controlling the pitch of the blades of a variable pitch, governor controlled, aerial propeller of which the pitch of the blades is variable between a coarse pitch limit and a fine pitch limit to match the torque of its prime mover has holding means (A) to maintain a forward thrust-generating blade pitch angle greater than the fine pitch limit with the prime mover idling as when an aircraft propelled by the propeller is taxi-ing whereby the propeller rotates more slowly, and hence more quietly, than it would otherwise. Preferably the holding means is effective by actuating a lock pitch solenoid valve (21) and an autofeather valve (18).