What happened
On 20 November 2013, a Robinson R66 helicopter, registration PR-MXM, was conducting a ferry flight from SBJR to the Hotel Porto Bello Helipad in Mangaratiba, Rio de Janeiro. While descending through approximately 400 feet, the aircraft experienced a sudden and total loss of control. The helicopter broke into three distinct sections while still in flight and plummeted vertically into a body of water near Junqueira Beach.
The pilot, who was the sole occupant of the aircraft, sustained fatal injuries. The aircraft was destroyed upon impact.
The investigation
CENIPA investigators examined the wreckage, which was recovered from the water and reconstructed in a hangar. The investigation focused on the structural integrity of the rotor system and the environmental conditions at the time of the accident. Analysis of the airframe, pitch links, and spindles revealed that these components had sustained fractures due to extreme overload.
Investigators also examined the main rotor blades, finding significant damage, including a downward deflection and a break perpendicular to the blade length. While the engine and main transmission were found to be in good working order with no evidence of mechanical failure prior to the event, the investigation looked into the possibility of aerodynamic phenomena affecting the two-blade rotor system.
Findings
- The primary contributing factor was the potential for mast bumping or the main rotor blades striking the fuselage, likely triggered by a low-G condition.
- Strong winds and local terrain near the beach may have created turbulent air drafts, inducing a low-G state.
- It is possible that the pilot's attempt to correct the aircraft's attitude during turbulence—specifically moving the cyclic forward—aggravated the low-G condition.
- The investigation noted that the pilot's specific training regarding the aerodynamic risks of the R66's rotor system could not be fully determined.