What happened
On June 25, 2011, a Schweizer 269C-1 helicopter, registration OK-XIS, was performing a landing at the private airfield in Šumvald, Czech Republic. The flight, which included the pilot and one passenger, had been intended as a photography flight, but the pilot decided to return to base due to heavy turbulence and gusty winds encountered over hilly terrain.
During the approach, a wind gust caused the aircraft to lose altitude, prompting the pilot to opt for a landing on a grassy area ahead of the runway. Upon touchdown, the helicopter began to veer to the right. The pilot attempted to correct the direction by applying left pedal, but the directional control failed to respond. In an attempt to stabilize the aircraft, the pilot applied cyclic and collective inputs, which inadvertently induced a skid. As the right skid struck a terrain irregularity, the helicopter rolled onto its left side, resulting in significant damage to the rotor blades, fuselage, and fuel tank. No injuries were reported.
The investigation
Investigators from the ÚZPLN examined the wreckage and the flight controls. A critical finding was the discovery of a broken left pedal control strut. Technical analysis by the Research and Testing Institute (VZLÚ) revealed that the fracture in the light alloy casting was caused by fatigue. The analysis showed that the internal structure of the casting contained impurities, which acted as stress concentaments, leading to the initiation of fatigue cracks.
While the manufacturer requires visual inspections of the pedals every 100 hours, the aircraft had flown only approximately 57 hours since its last inspection. The investigation established that the loss of directional control occurred during the landing rollout due to this structural failure.