Abstract: Main helicopter drive for transmitting drive to the countershaft even when the main shaft connected to the rotor is idle, and on which a sleeve, turned by a drive shaft and connected by gears to the countershaft, supports in rotary and axially-sliding manner, an inner tubular body angularly integral with the main shaft; an actuator being connected to the said tubular body for moving it between a normal position, in which the said tubular body is connected to the said sleeve by a freewheel on the latter, and a position in which the said freewheel engages the outer casing of a bearing fitted on to the said tubular body.

Abstract: Helicopter engine-drive assembly on which the engine and drive unit are connected by a propeller shaft extending inside an articulated tubular member connected in removable manner, at one end, to the casing on the engine and, at the other end, to the casing on the drive unit and consisting of at least two segments at least one of which consists of two portions connected telescopically and secured in a given mutual position by releasable, removable fastening means.