Incident Overview
A helicopter was conducting a mosquito control inspection flight after departing from an island. The pilot reported that while cruising at a manifold pressure of 23 inches and 2800 rpm at an altitude of 200 feet above the water, the engine began "missing" and failed to develop sufficient power to maintain flight.
Engine Malfunction and Pilot Actions
The engine sputtered and then regained full power. The pilot configured the helicopter for an autorotation at a forward airspeed of 50 knots. He stated that he had "split the needles" and set the engine rpm to 2,000. As he decelerated the helicopter at 50 feet above the water, the engine came back online. The pilot then "joined" the needles and established an attitude to continue flight.
Water Contact
During the recovery maneuver, the helicopter's landing skid contacted the water. The aircraft subsequently came to rest in the water.
Engine Test
After the incident, an engine test run was performed. Due to damage to the magnetos and ignition harness, these components required repair before the test could be conducted. Once repaired, the test run revealed no discrepancies at any power setting.