Departure and Weather Conditions
The pilot departed Tallahassee in marginal VFR conditions. The ceiling was estimated at 500-600 feet, ragged, with visibility between 3/4 and 1-1/2 miles in rain.
Maneuvers and Encounter with Heavy Rain
Observing towers about 3/4 mile in front of his flight path, the pilot reduced airspeed and turned right towards a borrow pit he had previously flown over. He then encountered heavy rain, with visibility dropping to about 1/2 to 1/4 mile, and the helicopter entered instrument flight conditions.
Descent and Impact
The pilot initiated a descent to 200 feet AGL, regained visual flight conditions, saw the borrow pit, and continued the descent with a fast closure rate. A deceleration described as similar to a quick stop was initiated. During this maneuver, the tailrotor collided with the water. The helicopter then pitched forward, the main rotor blades struck the water, and the helicopter rolled over onto its right side.
Pilot's Assessment
The pilot concluded that his judgment was impaired from fatigue due to lack of sleep.