I do not know if the original Wessex design had an American R-1820 or a British built recip. engine. But most importantly I do not know if the throttle rigging was the same as the H-34 or if the Westland version had a hydromechanical clutch. In any case I offer the following. This story deals with turning a brand new helicopter into a training aid in less than 15 seconds.
A brand new H-34 had just been ferried from Sikorsky in Bridgeport, Connecticut to Ft. Eustis, Virginia. When it arrived it had about 16 hours on the airframe and engine. For whatever reason it got through factory inspection with the throttle linkage mis-rigged. A new pilot was being checked out in the starting procedures and he was twisting the throttle while turning the engine over. With the mis-rigging of the throttle linkage the throttle-canceling switch was held closed allowing voltage to the starting solenoid. When the engine started to turn over and started to fire on all cylinders the throttle was more than half-open. The engine oversped to over 2800 RPM.
The forces were so great in the hydromechanical clutch the energy generated by the fly weights caused the blocker plate to fail and the engine went into a solid engagement at the speed indicated above. Within a split second the transmission not only failed it was torn away from the fuselage attach points and the blades just folded up. The rotorhead failed, as did the dampers. The tail rotor drive line failed and the tail rotor almost sheared away from its’ drive shaft. The engine was also severely damaged. Needless to say, the clutch and the cooling fan were also destroyed.
In complete disgust the CO of the airfield told his mechanics to tow the aircraft over to the training facility.