What happened
On 30 June 2022, a pilot conducting an ATPL(A) training flight experienced an engine failure in an Aero AT-3 R100, registration SP-PBC. Approximately 1 hour and 40 minutes after takeoff, the engine began to vibrate and the RPM dropped, leading to a complete engine stoppage. The pilot made two unsuccessful attempts to restart the engine while descending from an altitude of approximately 1,600 to 2,000 feet AMSL.
Seeking an emergency landing site, the pilot initially selected a field but changed the decision during the final approach phase to target a field with a milder crop. The aircraft attempted a landing in hilly terrain in a downhill direction. During the landing, the aircraft struck a local land elevation, causing the nose and main landing gear to detach. The impact triggered an uncontrolled ground loop of approximately 150 degrees. The pilot was uninjured, though the aircraft sustained substantial damage, including a broken propeller blade and a deformed fuselage.
The investigation
The PKBWL investigation examined the aircraft's fuel system, the engine performance, and the pilot's landing procedures. Investigators found that the fuel valve for the right wing tank was closed throughout the entire flight, meaning the engine was consuming fuel solely from the left tank. The investigation also reviewed the aircraft's maintenance and the pilot's flight history and training status.
Findings
- The primary cause of the engine stoppage was fuel starvation because the engine was being fed from an empty left tank.
- The fuel valve knob for the right tank was broken and worn, which prevented proper control of the valve.
- Prior to the flight, the fuel quantity on the left tank meter was incorrectly set, leading to inaccurate readings during the flight.
- The pilot attempted to land in a downhill direction in hilly terrain, which increased the risk of impact.
- The pilot attempted to land against the wind, despite the wind being weak and variable.
- The pilot did not follow the Flight Manual procedures for emergency landing, such as switching off the battery, alternator, and magnetos, or configuring the flaps correctly.
- Stress caused by the sudden engine failure and a lack of experience with uphill landings in difficult terrain contributed to the landing outcome.