What happened
On September 29, 2002, a Eurocopter SA 315B, registration CP-2402, operated by Heliamerica, was conducting external load and personnel transport operations in the Balsapuerto area under RAP 133 and 135 regulations. The aircraft departed from Drop Zone DZ9/559 with the intention of transporting a net containing empty containers to Balsa Puerto.
After the crew secured the external load, the helicopter attempted to lift off. During the ascent, the aircraft began to spin uncontrollably around its axis. This loss of control resulted in the helicopter striking nearby trees, where it eventually became entangled. The pilot and the cargo master were uninjured, though they were suspended approximately 23 meters above the ground following the impact.
The investigation
The investigation focused on the mechanical failure that occurred during the transition to flight. Investigators established that the aircraft suffered a catastrophic failure of the tail rotor assembly. Specifically, the transmission box, the hub, and the tail rotor became detached from the airframe.
Findings
- The primary cause of the accident was a mechanical failure involving the detachment of the transmission box, hub, and tail rotor, which led to the total loss of directional control.
- The failure was likely caused by the fatigue of the transmission box mounting bolts, which failed to keep the component secured.
- A contributing factor was the failure to comply with specific procedures outlined in the Basic Maintenance Manual.
Safety action
For the operator, Heliamerica, the following actions were recommended:
- Update the General Maintenance Manual to prevent maintenance personnel from inspecting their own recent work.
- Implement a control procedure to periodically verify the human performance of maintenance personnel.
- Establish an internal reporting system for unsafe conditions to facilitate risk management.
- Implement training programs for accident prevention and quality control personnel.
For the Directorate General of Civil Aeronautics (DGAC):
- Review the operator's General Maintenance Manual regarding inspection protocols.
- Increase the frequency of compliance verifications for procedures established in approved manuals.