Circumstances
The pilot, holding a PPL since 2001 with 120 total flight hours, was returning from a navigation flight to Thionville aerodrome. While on downwind for runway 20, he decided to perform a simulated engine failure exercise. He pulled the mixture control and turned onto base leg. On short final, he executed a steep left turn while below the nominal glide path, and the aircraft crashed into the garden of a house.
Examination
The aircraft struck a row of trees perpendicular to the trajectory, then a final tree before coming to rest on a heading of approximately 045°. The wreckage was spread over a small area. The engine was not externally damaged; both propeller blades were bent backward with leading-edge impact marks, indicating rotation without power. The cockpit flap control was found in the "first notch" position. The mixture control and carburetor heat controls were locked and pushed forward. The fuel pump switch was ON. The altimeter was set to 1020 hPa and indicated –100 ft.
Witness Statements
The passenger, who was a student pilot, reported that the pilot seemed calm. On downwind, the pilot announced "I will do an encadrement" and pulled the mixture control. The passenger remarked "that's not the usual procedure," and the pilot replied "you'll see." After turning base, the passenger noted a rapid speed decrease from 130 to 110 km/h. On short final, the pilot performed a left turn with about 60° bank. The passenger did not recall whether the pilot attempted to add power. A local resident heard an unusual noise and saw the aircraft descending on the normal final approach, then turn sharply left before disappearing.
Analysis
The accident originated from the pilot's action on the mixture control. Two possibilities were considered: either the pilot intentionally pulled the mixture to simulate engine failure, believing the engine would restart, or he inadvertently pulled it while intending to apply carburetor heat. The latter was deemed more probable given his usage habits. The pilot's limited recent dual instruction (about 5 hours in the previous 4 years) may have contributed to his decision to use an inappropriate technique. When he realized he could not reach the runway, he likely attempted to restore power but too late to avoid the trees.
Conclusion
The accident was due to an improvised decision to perform an engine failure exercise, the execution of this exercise through an inappropriate action on the mixture control, and the lack of verification of that control's position.