What happened
On January 9, 2011, at approximately 07:35 a.m., a Bell 427 helicopter, registration N926MF, was performing a private flight from Aeropuerto Internacional Dr. Joaquín Balaguer “El Higüero” toward Casa de Campo, La Romana. During the initial climb, roughly 3 km north of the departure airport, the crew experienced a sudden impact at the rear of the aircraft.
Following the impact, the crew notified the control tower of their intention to return to the airport. However, the aircraft struck several trees during its descent, leading to a near-vertical crash in a wooded area near Amor de Dios, Villa Mella. The two crew members on board sustained injuries, with one suffering serious injuries including a pneumothorax and rib fractures, while the other sustained moderate injuries. The aircraft suffered substantial damage, including the separation of the tail boom and destruction of the main rotor blades.
The investigation
The CIAA investigation focused on determining the cause of the sudden loss of control. Investigators examined the wreckage and found that the main rotor was still producing power at the time of the tree impacts. A critical component of the investigation involved the tail rotor assembly, which was sent to Bell Textron laboratories in Texas.
Upon inspection, investigators discovered organic material on the tail rotor blades. This led to DNA analysis conducted by the Smithsonian Institution in Washington, D.C., which confirmed the presence of biological matter from two species of migratory birds (Mallard and Maned Goose). Additionally, flight simulators were used to replicate the flight conditions, including the low altitude and high-frequency vibrations, confirming that such an event leads to an unrecoverable loss of control.
Findings
- The primary cause of the accident was a bird strike involving two migratory birds hitting the tail rotor.
- The impact on the tail rotor blades induced high-frequency vibrations and a subsequent loss of anti-torque effectiveness.
- The low altitude of the aircraft (approximately 600 feet) and the presence of vegetation prevented the crew from recovering the aircraft after the loss of control.
- The crew was properly licensed and the aircraft was maintained in accordance with all applicable regulations.