The pilot was undergoing a routine currency check with a flying instructor. As part of the check the pilot was asked to carry out a hover taxiing autorotation. The power was reduced to flight idle with the aircraft about 5 feet above ground level and moving forward at taxiing speed. The pilot carried out what was considered to be a normal landing, however, shortly after touchdown a loud bang was heard and the tail rotor and stabiliser were seen to land in front of the aircraft. The tailboom had been severed by the mainrotor during the landing. Indentations left by the skids in the soft ground indicated that the aircraft moved forward about 4 metres after initial ground contact. The main rotor was found to have an excessive static droop angle which reduced main rotor tip clearance from the tailboom by approximately 75 millimetres. This, in combination with attitude changes during the touchdown on the soft surface, rotor tilt and reduced rotor RPM, was contributory to the development of the accident.