What happened
The pilot of the Cessna 140 reported that the aircraft encountered wake turbulence while established on short final approach. The disturbance caused the airplane to roll abruptly to the right. In an attempt to recover control, the pilot applied corrective inputs, but the aircraft subsequently impacted the runway with excessive vertical speed. This hard landing resulted in the collapse of the right main landing gear. Following the gear failure, the aircraft ground-looped to the right before coming to a stop. A preceding Sweezyen Commuter aircraft had landed on the same runway just minutes prior, which was identified as the source of the wake turbulence.
The investigation
Examination of the accident site and the aircraft revealed significant damage to the right main landing gear assembly. The structural failure was consistent with the forces generated by a hard landing following an uncommanded roll. No mechanical failures were found that would have contributed to the loss of control prior to the turbulence encounter.
Findings
The pilot's inability to maintain directional control and altitude due to the sudden lateral displacement caused by the wake vortex led directly to the hard landing. The proximity of the preceding aircraft's departure from the runway surface created a hazardous wake condition for the following aircraft. The resulting ground-loop exacerbated the damage to the airframe.
Safety message
Pilots operating behind larger or heavier aircraft should remain vigilant for wake turbulence, particularly during the final approach phase. Maintaining adequate spacing and being prepared for sudden control inputs is essential to mitigate the risks associated with vortex encounters.