What happened
On December 7, 2020, at approximately 12:00, a Tecnam P2006T aircraft, registration SP-DZW, was conducting a multi-engine (ME) training flight as part of an integrated ATPL(A) program. The crew, consisting of an instructor and a student, was performing a specific training maneuver involving the shutdown and subsequent restart of an engine.
During the procedure, the crew successfully shut down the right engine; however, they were unable to restart it. Faced with the single-engine operating condition, the instructor decided to land the aircraft at Watorowo (EPWT). After landing, the aircraft taxied to a hangar, where the left engine was also shut down. Following the connection of an external power source, the right engine restarted without difficulty. The battery was subsequently replaced with a new unit, and both engines were successfully restarted, allowing the aircraft to return to service.
The investigation
The investigation focused on why the right engine failed to restart after the intentional shutdown. Investigators examined the battery's state of health and the meteorological conditions present during the flight. It was determined that the battery's capacity had dropped below the required threshold. Additionally, the investigation reviewed the maintenance logs, noting that a capacity check performed during a 100-hour inspection on December 4, 2020, had shown a capacity of 82%.
Findings
- The primary cause of the incident was the battery capacity dropping below the permissible 80% limit.
- Meteorological conditions during the flight, characterized by an air temperature of 2.7°C and a dew point of -2.6°C, were identified as contributing factors, as these conditions were conducive to carburetor icing, which may have hindered the restart attempt.