What happened
On October 9, 2021, a Diamond Aircraft Industries DA40D was conducting a dual flight training mission near Beernem, Belgium. The flight, which originated from Ostend Airport, was performing a series of navigation exercises and simulated forced landing maneuvers. During the session, the crew noticed a reduction in engine power, which eventually led to a complete loss of engine function.
As the aircraft climbed, the crew observed a drop in oil pressure and noticed oil fumes emanating from the engine cowling. With the engine no longer operating, the instructor took control of the aircraft. To avoid the village of Knesselare and manage the descent, the instructor selected a landing site in a nearby field. After initially identifying a potential zone blocked by a wooden fence, the crew maneuvered the aircraft into a beet field. The aircraft slid through the beet field and came to a stop in a corn field. Both the instructor and the trainee exited the aircraft without injuries.
The investigation
AAIU(Be) conducted a limited-scope investigation into the mechanical failure. Technical analysis of the engine, performed in coordination with German authorities, revealed significant internal damage. Investigators found broken aluminum chips and a copper bushing within the engine compartment, alongside evidence of heavy oil loss.
Data from the engine's electronic control unit (ECU) indicated that fluctuations in oil pressure and temperature had begun several minutes before the engine failure became apparent in the cockpit. While a defect was found in the FADEC system's high-voltage generation, this was not determined to be the primary cause of the engine's mechanical breakdown.
Findings
- The investigation determined that damage to the number two piston was the primary cause of the failure.
- This damage was triggered by a combustion anomaly that created a localized hot spot on the piston.
- The resulting breach allowed hot combustion gases to leak into the crankcase, causing internal components to overheat.
- The specific origin of the initial combustion anomaly could not be identified.