Hiller UH-12E accident near Bovill, Idaho, September 23, 2021
On September 23, 2021 at about 10:00 pm local time, a 1959 Hiller UH-12E (helicopter), registered N5334V, was substantially damaged in an accident during maneuvering (hover) near Bovill, Idaho. It was an aerial application (crop spraying) flight under agricultural flying rules (Part 137). No one was hurt; 1 person was on board or involved. The weather was visual conditions (good weather).
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The NTSB's probable cause their words, unchanged
A loss of helicopter control for undetermined reasons based on the available evidence for this accident.
Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- September 23, 2021 · about 10:00 pm local time
- Place
- Bovill, Idaho · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Hiller UH-12E, built 1959 · all UH-12Es on the register
- Registration
- N5334V · no longer on the register · serial 2008
- Damage
- Substantial damage
- Flight
- Aerial application (crop spraying) flight · agricultural flying rules (Part 137)
The NTSB's narrative final · quoted from the NTSB record
The helicopter was performing an aerial application flight. While approaching the fertilizer service truck to refill the bucket, the pilot felt a “sudden jolt,” and the helicopter lost altitude. The pilot was unable to regain control, and the helicopter did not yaw after the jolt. The helicopter subsequently impacted the terrain below. The helicopter sustained substantial damage to its main rotor blades and fuselage. Before the pilot could exit the helicopter, “everything” on the helicopter, including the engine, automatically shut down. Postaccident examination of the wreckage, including the engine, revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. Also, the examination yielded no evidence to explain why the engine automatically shut down after the accident. As a result, the reason for the pilot’s loss of helicopter control could not be determined based on the available evidence for this accident investigation.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
What happened, in order
- Loss of engine power (partial) during maneuvering (hover)
- Loss of control in flight during maneuvering (hover)
- Unknown or undetermined during maneuvering (hover) defining event
The NTSB's findings
- Personnel issues › Task performance › Use of equip/info › Aircraft control › Pilot
- Not determined › Not determined › (general) › (general) › Unknown/Not determined
Pilot
- Certificate: commercial pilot
- Ratings: rotorcraft: helicopter
- Flight time: 450 hours in all; 46 in this make and model; 380 as pilot in command
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: ctr
- Injury: no injuries
The aircraft
- Airframe total time: 21,096 hours
- Last inspection: 100-hour inspection, September 22, 2021; 5.8 hours since
- Maximum gross weight: 3,100 lb
- Seats: 3
- Landing gear: fixed
- Engine: Rolls-Royc 250-C20B (turboshaft); 15,414 hours total
- Operator: Western Helicopter Services
The flight
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 230° at 5 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 68°F (20°C), dew point 41°F (5°C)
- Altimeter: 30.26 inHg
- Observation at 2:53 pm from KPUW, 34 miles away
Weather report (METAR): KPUW 232153Z AUTO 23005KT 10SM CLR 20/05 A3026 RMK AO2 SLP242 T02000050
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flig | 1 |
About this page
Everything above comes from the NTSB's public accident database: the narrative, probable cause and findings are the NTSB's own words, and the coded tables behind its report (pilot, aircraft, flight, weather, injuries, sequence of events) are written out in plain English. Pilots' ages, home towns and medical details are left out on purpose. The docket at the NTSB holds the report as a PDF and the investigation's photographs and documents. This site never names pilots, passengers or anyone else involved. A preliminary report describes what is known soon after the event and can change; the final report, with the probable cause, usually follows one to two years later and this page is refreshed when it does. Case number WPR21LA354.