What happened
On 25 January 2020, a private flight departing from the Morgan Bay Hotel toward Glen Eden ended in an emergency landing near the Haga-Haga Holiday Resort. The flight, conducted under visual flight rules, proceeded normally for approximately eight minutes. While cruising at 600 feet, the pilot observed a low rotor RPM warning light, followed by a drop in engine RPM. The engine subsequently began running roughly before failing completely.
In response to the power loss, the pilot initiated an autorotation. However, during the flare maneuver intended to cushion the touchdown, the descent rate was not sufficiently reduced. This caused the helicopter skids to strike the soft ground of the beach with significant force. During the impact, the main rotor struck the tail boom, resulting in substantial damage to the Sanka AK 1-3 (registration ZU-RNJ). The pilot escaped the crash without any injuries.
The investigation
An investigation by the SACAA AIID focused on the mechanical failure of the Subaru EJ-25 engine. While the engine had passed a pre-flight inspection and showed no external anomalies, a post-accident examination of the engine components revealed a critical fault. Investigators discovered that the ignition coil plug, which provides spark to all four cylinders, had become detached during flight.
Upon closer inspection of the hardware, the investigation found that the rubber latch on the interior of the plug was damaged. This damage prevented the plug from locking securely into the engine's fixed connector. Because the plug was not properly seated, it was able to pull away from the connector in-flight, cutting off the electrical connection to the spark plugs.