What happened
On March 7, 2013, a Zlín Z126T, registration OK-KMM, was performing a repositioning flight to Otrokovice for scheduled maintenance. Shortly after takeoff from Hranice Airport, at an altitude of approximately 15 meters, the engine suddenly failed without warning.
The pilot attempted to restart the engine while in flight, but the propeller continued to rotate freely, indicating a loss of power. To avoid a nearby stream bed located directly ahead of the runway, the pilot maneuvered the aircraft to the left. The aircraft subsequently made a hard landing on a field between a road and the stream. During the impact, the left wing struck the ground first, followed by the main landing gear and the engine. The aircraft sustained significant damage, including a deformed fuselage and broken landing gear, and a fuel leak occurred due to damaged lines. The pilot was uninjured.
The investigation
An investigation by the ÚZPL and a technical inspection of the Walter Minor 4-III engine were conducted. Investigators examined several hypotheses regarding the engine failure. One theory suggested that missing aluminum inserts in the exhaust manifolds might have caused ice to form in the intake manifold; however, this was ruled out because the engine failure was sudden, whereas intake icing typically causes progressive power loss and irregular running.
Investigators also examined the fuel system, specifically the fuel selector valve and the secondary fuel tank. Comparative ground tests on a similar aircraft demonstrated that the fuel supply remained functional under various valve settings. While the investigation noted that the pilot's attempt to restart the engine at such a low altitude may have diverted attention from maintaining a proper flight path for the landing, no mechanical defect could be definitively linked to the sudden loss of power.
Findings
- The engine suffered a sudden failure during the climb phase that could not be technically explained.
- The pilot was qualified and the aircraft was airworthy and maintained according to regulations.
- The pilot's application of emergency procedures was imprecise, as the attempt to restart the engine at a very low altitude may have hindered the ability to stabilize the aircraft'for landing.