What happened
On August 10, 2021, a pilot operating a Flight Design CTLSi, registration SP-SMED, was performing a flight from Katowice-Muchowca (EPKM) to Lublin (EPLB). Approximately 35 minutes into the flight, the pilot observed engine roughness, followed by a partial loss of power, a drop in oil pressure, and an increase in oil temperature. After notifying Kraków FIS of the emergency, the pilot diverted to Kielce-Masłów (EPKA).
Two minutes after the initial symptoms, the oil pressure dropped to zero and the oil temperature rose above 150°C. Roughly four minutes before reaching the destination airport, the engine ceased operation entirely. The pilot executed an emergency landing in an unprepared field near Bęczków. The aircraft sustained no damage during the landing, and the pilot was able to secure the site and notify emergency services of the safe outcome.
The investigation
Post-landing inspections revealed that the engine was seized and blocked, with a total absence of oil. The engine, windshield, and fuselage were heavily coated in oil. Investigators found no damage to the oil lines or the oil cooler. At the time of the incident, the engine had 403.3 hours of total time since new (manufactured in 2019). All maintenance had been performed by a qualified mechanic following the Rotax 912 iS maintenance manual. The engine was sent to the manufacturer via a national distributor for a warranty claim, and the manufacturer intended to honor the claim.
Findings
- The primary cause of the engine failure was an undetermined manufacturing defect in the rear seal (simmering) of the propeller shaft.