What happened
On March 27, 2011, a Robinson R44 II, registration I-HEHL, was conducting a recreational flight near Monte Argentario. During the flight, the pilot observed the "clutch caution light" illuminate for approximately 15 to 20 seconds. In response to this warning, the pilot decided to perform an emergency landing on a beach in the Pozzarello area, south of Porto S. Stefano.
Shortly after taking off from the beach, the clutch warning light reappeared. The pilot subsequently attempted to land on a small concrete pier located about 100 meters from the takeoff point. This pier measured approximately two meters in width and fifteen meters in length. During the landing maneuver, the helicopter tilted, struck the pier, and slid into the sea, where it settled in water roughly one meter deep. The pilot survived the incident without injury.
The investigation
Investigators examined the wreckage and identified significant saltwater intrusion within the engine, airframe, and various systems. The fuselage showed impact damage from striking the concrete pier, and there was notable damage to the tail rotor blades and structure. The main rotor blades also sustained substantial impact damage.
Technical analysis of the drive system revealed that the drive belts had jumped out of their grooves on the driven pulleys. However, investigators found no evidence of belt slippage, pre-existing wear, or abnormalities in the belt tensioning system. The investigation also noted that all electrical breakers in the cabin had tripped, with the exception of those for the navigation and landing lights. The damage patterns indicated that the helicopter entered the water at a very low forward speed, with the main rotor still rotating but not under power.
Findings
- The primary cause of the accident was the loss of control during the landing phase due to the use of an unsuitable landing surface.
- The dimensions of the concrete pier were insufficient to provide a stable landing area for the helicopter's skids.
- The physical constraints of the pier caused the aircraft to tilt and slide into the water upon contact.
- While the clutch caution light had prompted the initial diversion, the investigation found no pre-existing mechanical faults in the belt tensioning system that would have caused the warning.