What happened
On August 3, 2021, a Cessna 337H was conducting a cross-country flight from San Fernando (SCSD) to Diego Aracena (SCDA) in the Tarapacá Region. The flight, which included a passenger, initially proceeded as planned with a scheduled stop at Caldera (SCCL). However, approximately 69 nautical miles south of the destination airport, the aircraft's front engine stopped running, and the rear engine began to sputter.
Facing imminent engine failure, the pilot executed an emergency landing on the Route 1 highway near the Playa Quebrada Honda-Caleta Honda sector in the Antofagasta Region. Despite the emergency, the pilot and the passenger escaped without injuries, and the aircraft sustained no damage.
The investigation
DGAC Chile investigators examined the aircraft's maintenance records, fuel configuration, and the pilot's flight planning. The investigation focused on why the aircraft ran out of fuel despite an initial plan that estimated a two-hour reserve upon arrival.
Investigators reviewed the aircraft's long-range tank configuration and the fueling process at the departure airfield. They also analyzed the pilot's flight logs, which revealed that the flight path and altitude profiles had deviated from the original flight plan. The investigation included a physical inspection of the engines, propellers, and fuel systems at the crash site, as well as an evaluation of the pilot's knowledge of specific aircraft fueling procedures.
Findings
- The primary cause of the engine failure was fuel exhaustion in the left wing tank and critically low fuel in the right wing tank.
- The pilot was unaware of a specific safety precaution in the aircraft's flight manual, which requires checking the opposite wing after fueling to ensure the tanks are full; consequently, the aircraft was loaded with less fuel than the pilot had planned.
- The flight deviated from the original plan through the inclusion of an unplanned intermediate stop and various changes in altitude, both of which increased the total fuel consumption.
- The pilot failed to monitor the fuel quantity using the cockpit indicators during the flight, which would have provided early warning of the decreasing fuel levels.