What happened
On April 26, 1999, a Moravan Zlin Z 126 "Trener" was conducting aerobatic training maneuvers near Altenburg-Nobitz. After completing several circuit patterns, the flight instructor and a student pilot departed the circuit to perform advanced aerobatic exercises. During the return flight to the airfield, the aircraft's engine experienced a sudden loss of power.
As the aircraft approached the runway, the student reported seeing smoke and flames originating from the right side of the engine compartment. The flight instructor took control, closed the fuel valve, and attempted an emergency landing in a nearby field. During the approach, the cockpit canopy became obscured by oil and smoke, prompting the instructor to slide the canopy open to improve visibility.
As the aircraft descended, it entered a steep nose-down attitude. The instructor attempted to recover the aircraft, but the elevator failed to respond effectively. The aircraft struck the ground at a steep angle, causing the student pilot to sustain fatal injuries. The instructor sustained serious injuries but survived the impact.
The investigation
The BFU examined the engine, the wreckage, and witness testimonies. Investigators analyzed the engine's internal components and found significant mechanical damage. Witnesses observed the aircraft wobbling and pitching forward at a low altitude. While the instructor reported seeing flames in flight, investigators found no evidence of an in-flight fire; instead, witnesses noted that a fire broke out in the engine area immediately after the impact. The investigation also looked into the engine's maintenance history, noting that the engine had not undergone a specialized overhaul in 27 years.
Findings
- The engine failure was caused by a bearing failure that led to a broken connecting rod and the subsequent seizure of the crankshaft.
- The specific cause of the bearing failure could not be definitively determined, though evidence of oil starvation was present.
- The aircraft entered an accelerated stall/overstressed flight condition because the pilot failed to maintain the minimum required airspeed during the emergency landing.
- Visibility was significantly impaired by oil and smoke obscuring the canopy.
- The impact was non-survivable for the occupant in the front seat.