What happened
On March 20, 2014, an AgustaWestland A109S helicopter, registration YV357T, was performing a flight from Helipuerto “Ávila” in Guarenas to Arturo Michelena International Airport in Valencia. The aircraft was carrying two crew members at a cruise altitude of 4,200 ft.
During the cruise phase, the pilot identified a loss of control regarding the collective pitch. The pilot notified the Maiquetía Area Control Center and subsequently performed an emergency landing in a sector of the La Bonanza landfill located in Charallamente, Miranda State. Both the pilot and co-pilot were uninjured, and the aircraft sustained only minor damage.
The investigation
The investigation examined the mechanical state of the aircraft's control system following the incident. Inspectors found that a bolt (part number NAS6606D28) connecting the scissors assembly to the control plate had fractured at its base, near the housing in the control plate. This fracture caused the scissors assembly to disconnect, rendering the collective control system inoperable.
Findings
- The primary cause of the incident was the incorrect installation of the lower scissors (part number 109-0134-10-105) into the main rotor control plate, which led to an overstress condition that fractured the connecting bolt.
- Contributing factors included a lack of adequate supervision, inspection, and certification of maintenance work orders, as well as failure to comply with mandatory service bulletins.