CEN26LA175

On April 30, 2026, about 1730 central daylight time, a Hiller UH-12E, N22SP, was substantially damaged when it was involved in an accident near Chickasha, Oklahoma. The pilot was not injured. The helicopter was operated as a Title 14 Code of Federal Regulations Part 137 aerial application flight. The pilot reported that he had completed two aerial application flights earlier that day and performed preflight inspections before both. About 1700, he began spraying a field and during the flight, the main rotor “developed a vertical hop,” and he observed one of the control rotor blades separate from the helicopter. The helicopter violently shook, and he conducted a forced landing to a field. During the landing, the main rotor blades struck the tail boom, which severed the tail boom near the tail rotor. The responding FAA inspector and the pilot located the separated control rotor blade in the field about 100 yards from the accident site. A review of the FAA airworthiness directives (AD) indicated that AD 97-10-16 was applicable to the Hiller UH-12 helicopter. The AD required (in part) that the control rotor blade spar tube (or cuff) be inspected for corrosion or cracks, or elongation, corrosion, burrs, pitting or fretting of the bolt holes…during the annual inspection, not to exceed 100 hours and every 100-hours thereafter. The actions specified by the AD are intended to prevent separation of the control rotor blade assembly and subsequent loss of control of the helicopter. According to the helicopter maintenance records, an annual inspection was completed on February 20, 2026. During the inspection, the control rotor cuffs and trunnions were overhauled and reinstalled in accordance with the Hiller overhaul manual. The records show that AD 97-10-16 was complied with at this time. The separated control rotor was retained for further examination.