Hiller UH-12E Sustains Substantial Damage After Rotor Blade Separates Near Chickasha, OK

A Hiller UH-12E helicopter, registration N22SP, was substantially damaged April 30 during an aerial application flight near Chickasha, Oklahoma. According to a preliminary National Transportation Safety Board (NTSB) report, the accident occurred at approximately 5:30 p.m. CDT when the pilot observed a control rotor blade separate from the aircraft during a spraying operation.

The pilot reported that the main rotor developed a "vertical hop" and the helicopter began shaking violently. During the subsequent forced landing in a field, the main rotor blades struck the tail boom, severing it near the tail rotor. An FAA inspector and the pilot later located the separated control rotor blade approximately 100 yards from the crash site. The pilot was not injured.

Maintenance and Regulatory Review

Investigators are reviewing compliance with Airworthiness Directive (AD) 97-10-16, which requires inspections of the control rotor blade spar tube and cuff for corrosion, cracks, or elongation to prevent blade separation. Maintenance records indicate the aircraft underwent an annual inspection Feb. 20, 2026, during which the control rotor cuffs and trunnions were overhauled and the AD was signed off as complied with. The separated blade has been retained for further examination. The Hiller UH-12 series remains a widely used platform in agricultural aviation, making rotor system integrity in these legacy aircraft a subject of ongoing regulatory attention.