What happened
On 02 July 2010, a Eurocopter EC 120B, registration ZS-RME, was conducting a scheduled operator's proficiency check near Cape Town International Airport. The flight, involving an instructor and a trainee, was operating under Visual Flight Rules (VFR) in favorable weather conditions.
During the training session, the crew performed several simulated engine failure maneuvers. After successfully completing an initial autorotation, the crew transitioned to a second maneuver from a downwind position at 1,000 feet AGL. During this second attempt, the instructor observed the engine RPM dropping below normal idle levels. Upon realizing that engine power had been lost, the trainee proceeded with standard autorotation procedures.
As the aircraft touched down, it maintained forward momentum and skidded approximately three meters across the soft terrain. The impact caused the main rotor blades to strike the tail boom, resulting in the boom being severed from the airframe. The aircraft sustained substantial damage, including a broken windscreen and a damaged pitot tube, but both pilots escaped the wreckage without injury.
The investigation
SACAA AIID investigators examined the wreckage and performed several technical inspections on the engine and control systems. The investigation included a review of the aircraft's maintenance history, which showed the helicopter had undergone a mandatory periodic inspection only 10.4 hours prior to the accident.
Engine inspections revealed that the power turbine rotation was free and showed no evidence of overheating or metal-to-metal contact. Furthermore, fuel samples and filters were analyzed, and no contamination or anomalies were detected. The investigation also confirmed that the fuel shut-off valve was found in the closed position, though the exact reason for the power loss remained elusive.
Findings
- The primary cause of the accident was an unsuccessful autorotation resulting in a hard landing due to an undetermined loss of engine power.
- While the investigation could not definitively establish why the engine power decreased, an unintentional engine shutdown could not be ruled out.
- The aircraft was properly maintained, and all pilots held valid licenses and medical certificates.
- The weather conditions were favorable for VFR operations at the time of the incident.