Incident Overview
A certified flight instructor (CFI) was conducting a training session on low rotor RPM recovery techniques during climb out after takeoff. The student pilot was tasked with taking the controls and recovering the helicopter to a 4-foot hover.
Sequence of Events
At an altitude of approximately 30 feet, with rotor RPM at 2,900, the student took control and opened the throttle but simultaneously pulled collective pitch. The engine RPM subsequently dropped below 2,500. The CFI then took over, verified that the throttle was open, and lowered the collective.
Landing and Damage
During the ensuing run-on landing, after touchdown, the main rotor blades contacted the tail boom, resulting in damage.
Engine Examination
A mechanic with inspection authorization examined the engine. The examination revealed that one of the packing seals, which seal the distribution zone pipe to the inlet manifold, had separated for undetermined reasons. This separation resulted in a partial loss of engine power.