Robinson R44 N7186Z accident near San Diego, California

Probable cause

The pilot's failure to utilize carburetor heat during initial climb, which resulted in a loss of engine power due to carburetor icing.

NTSB analysis

Shortly after departure and at an airspeed of 60 knots, the engine lost power. The pilot reported that the airspeed decreased, the low rotor rpm horn sounded, and the manifold pressure increased. The pilot then began to maneuver the helicopter into the wind for an autorotation; however, the helicopter was descending rapidly, and the pilot was unable turn completely into the wind prior to touchdown. About 100 feet above water level, he deployed the helicopter’s floats and pulled the nose up into a flare. The tailboom hit the water first, and the helicopter subsequently sank.

During the postaccident airframe examination, it was noted that the carburetor heat tab had been released, and the carburetor heat knob, which is located in the center console, was in the OFF (down) position. Further examination of the airframe and engine revealed no mechanical failures or malfunctions that would preclude normal operation. The conditions encountered at the time of the accident were conducive to serious carburetor icing for glide power and icing for glide and cruise power. As a result of the pilot's failure to utilize carburetor heat, it is likely that the engine lost power due to carburetor icing.

Text from the NTSB. Open the NTSB docket for WPR10LA420 for the full record.