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Sikorsky CH-53K Helicopter Ground Test
The "Bare Head Light-off" phase of testing - so named because no rotor blades are attached -- began under auxiliary power in December with safety-of-flight test pilots at the aircraft's controls. Not too soon after the January 17 event, the rotor head turned without blades on January 24. By January 24 the rotor head was engaged (turning without blades) under engine power.