# NTSB CEN26LA175: Hiller UH-12E, N22SP, Chickasha, OK, April 30, 2026

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Class 3 · Limited · Preliminary report
- Date: April 30, 2026, 17:30 local (22:30 UTC)
- Place: Chickasha, OK
- Coordinates: 34.981681, -97.973939
- Nearby events: https://openairdocs.org/map.md?lat=34.9817&lon=-97.9739&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Defining event: [Maneuvering-low-alt flying: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Investigation ongoing
- Investigation class: Class 3
- NTSB office: Central Region
- Parties: FAA
- ADs cited in the narratives: [AD 97-10-16](https://openairdocs.org/ad/97-10-16) (OpenAirDocs)
- NTSB case key (mKey): 202933
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN26LA175
- NTSB preliminary report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/202933/pdf
- Page: https://openairdocs.org/ntsb/CEN26LA175

## Preliminary report

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.

## Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event best describes what happened.

- [Maneuvering-low-alt flying: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) (defining event); cases with it: [Hiller UH-12E, 5 cases](https://openairdocs.org/ntsb-events/330/sequence.md?model=4360122), [All aircraft, 994 cases](https://openairdocs.org/ntsb-events/330/sequence.md)
- [Maneuvering-low-alt flying: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338); cases with it: [Hiller UH-12E, 2 cases](https://openairdocs.org/ntsb-events/338/sequence.md?model=4360122), [All aircraft, 563 cases](https://openairdocs.org/ntsb-events/338/sequence.md)

## Aircraft

- Registration: [N22SP](https://openairdocs.org/aircraft/N22SP), registered now, S/N 1214, built 1959 (OpenAirDocs)
- Reported make and model: HILLER UH-12E
- Registry model: [Hiller UH-12E](https://openairdocs.org/model/hiller-uh-12e) (registry code 4360122) (OpenAirDocs)
- Registry engine: [Lycoming VO-540-C2A](https://openairdocs.org/engine/lycoming-vo-540-c2a) (registry code 42244, reciprocating) (OpenAirDocs)
- Category: Helicopter
- Serial number: 1214
- Year built: 1959
- Airframe hours: 8033
- Damage: Substantial damage
- Flight: Aerial application, Part 137
- Registered owner: Paragon Helicopter Services LLC
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: Annual, February 20, 2026
- Destination: Same as departure
- Airport: N/A

## Weather

- Conditions: Visual (VMC), Day
- Wind: 40° at 13 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 68 °F, dew point 41 °F
- Altimeter: 29.99 inHg
- Observed at: KCHK, 7 nm away
- METAR: METAR KCHK 302235Z AUTO 04013KT 10SM CLR 20/05 A2999 RMK AO2

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 20260430003599A](https://openairdocs.org/incident/20260430003599A), Apr 30, 2026: Hiller UH-12E, Chickasha, OK, Substantial damage. On April 30, 2026, at approximately 1730 a [privacy data omitted] helicopter was traversing between fields where it was spraying agricultural products, when…

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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