What happened
On the morning of the incident, a Robinson 44 Raven II helicopter, registration LV-BRN, departed from San Fernando International Airport in Buenos Aires, Argentina, at 08:45. The aircraft was operating under VFR flight rules with three occupants on board, destined for Ángel S. Adami International Airport (Melilla).
During the initial engine start sequence, the pilot noted an unusual noise. While flying north of Colonia, the crew received information via frequency 120.8 MHz indicating that weather conditions at both Adami and Carrasco airports were below minimums. Consequently, the pilot decided to return to Colonia. During this diversion, the "STARTER ON" amber warning light illuminated. For safety reasons, the pilot elected to perform a precautionary landing in an open field.
Following the landing, the pilot attempted to restart the engine, but the aircraft remained unable to start. The pilot then contacted an acquaintance to notify the relevant authorities of the situation.
The investigation
The CIAIA investigation focused on the mechanical failure of the propulsion system components. The examination established that the starter motor bendix and the ring gear had experienced significant wear. This level of degradation was sufficient to prevent the starter motor from successfully rotating the engine.