What happened
On August 11, 2020, at approximately 15:50 UTC, a Diamond DA-42, registration SP-TRL, was conducting an IFR training flight on a route between EPBC and EPMO. While being vectored for the ILS 08 approach at EPMO, the aircraft experienced a momentary loss of power in the left engine. After verifying that all engine parameters had returned to normal, the crew decided to abort the mission and return to EPBC at a safe altitude. The crew notified AFIS Warszawa of the situation.
The aircraft landed on runway 10 at EPBC at 16:13 UTC without further incident. However, while performing a 180-degree turn on the runway, the left engine shut down. This failure prevented the aircraft from vacating runway 10, resulting in the runway being blocked for approximately five minutes.
The investigation
During a post-event inspection of the aircraft, investigators discovered that the flexible fuel lines were incorrectly connected to the fuel tank. Specifically, the fuel supply line had been connected to the fuel return fitting, while the overflow line (from the auxiliary tank) had been connected to the supply fitting. This configuration caused the engine to draw fuel from the upper point of the tank rather than the lower point. As the fuel level dropped below the connection point of the return line, the engine lost its fuel supply.
It is believed that this reversed installation likely occurred during the aircraft's last structural inspection, which took place at the 1,000-hour flight interval.
Findings
- The primary cause of the engine failure was the incorrect connection of the flexible fuel supply and return lines to the fuel tank.
- A contributing factor was the aircraft design, which allowed the lines to be swapped without any physical prevention mechanism or error-proofing.
Safety action
- The operator has accepted a recommendation to use distinct colors to mark the tank fittings and the end caps of the fuel lines during future periodic maintenance inspections.