Bell OH-58A accident near Guernsey, California, August 9, 2023
On August 9, 2023 at about 7:30 pm local time, a 2013 Bell OH-58A (helicopter), registered N861CC, was substantially damaged in an accident during maneuvering (low-alt flying) near Guernsey, California. It was an aerial application (crop spraying) flight under agricultural flying rules (Part 137). 1 person had minor injuries. The weather was visual conditions (good weather).
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The NTSB's probable cause their words, unchanged
The pilot’s overpitching of the main rotor blades while maneuvering at low altitude in a high-temperature environment at high gross weight, which resulted in a reduction of engine and rotor speed, excessive main rotor blade flapping, mast bumping, and impact with terrain.
Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 9, 2023 · about 7:30 pm local time
- Place
- Guernsey, California · map
- Type
- Accident
- Injuries
- 1 person had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Bell OH-58A, built 2013 · all OH-58As on the register
- Registration
- N861CC · registry record · serial 71-20861
- 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 pilot was conducting an aerial application flight and initiated a climbing left turn to return to the field. The helicopter’s low rotor rpm warning light illuminated, and the pilot heard the low rotor audio tone in his headset. The pilot lowered the collective to attempt to regain engine and rotor speed while maneuvering to avoid a drainage culvert. While the pilot was maneuvering, tThe tailboom separated, the right skid contacted the culvert, and the helicopter rolled over onto its right side. T; the helicopter sustained substantial damage to the fuselage and the tail rotor had separated from the tailboom. Examination of the helicopter, including the transmission and hydraulic systems, revealed no preaccident mechanical malfunctions or failures that would have precluded normal operation. The tailboom was completely separated just aft of the horizontal stabilizers, severing the tail rotor and gear box. Witness marks from the main rotor blades were observed on the tail rotor driveshaft cover, aft of the horizontal stabilizers. A test run of the engine revealed no anomalies. The helicopter was loaded about 21 pounds below its maximum gross weight and operated in a high-temperature environment. Performance calculations based on the pilot’s estimates of environmental conditions and the helicopter’s weight revealed 5 minute maximum power availability of about 92% torque. It is likely that while trying to maintain the climbing left turn, which required increased lift due to the increased load factor, the pilot demanded more power than the engine could produce and overpitched the main rotor blades. The resulting low rotor speed led to a reduction of lift and stiffness and lag in the flight control response, which the pilot interpreted as a hydraulics failure. It is likely that while the pilot maneuvered to avoid the culvert, the low rotor speed allowed the main rotor blades to flap down and sever the tailboom. At the same time, the main rotor hub teetered downward and fractured the mast, consistent with mast bumping, which separated the main rotor system from the transmission.
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
- Attempted remediation/recovery during maneuvering (low-alt flying)
- Mast bumping during maneuvering (low-alt flying) defining event
- Collision with terrain or object (not controlled flight into terrain) during maneuvering (low-alt flying)
- Loss of control in flight during maneuvering (low-alt flying)
The NTSB's findings
- Personnel issues › Task performance › Use of equip/info › Use of equip/system › Pilot
- Personnel issues › Task performance › Use of equip/info › Aircraft control › Pilot
- Personnel issues › Action/decision › Action › Incorrect action performance › Pilot
- Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Powerplant parameters › Capability exceeded
- Aircraft › Aircraft propeller/rotor › Main rotor system › Main rotor blade system › Capability exceeded
Pilot
- Certificate: commercial pilot
- Ratings: rotorcraft: helicopter
- Flight time: 8,842 hours in all; 7,000 in this make and model; 314 in the last 90 days; 153 in the last 30 days; 8,819 as pilot in command
- Last flight review: March 26, 2023
- Medical certificate: Class 2
- Seat: rgt
- Injury: minor injuries
The aircraft
- Airframe total time: 6,168.7 hours
- Last inspection: annual inspection, March 20, 2023
- Maximum gross weight: 3,200 lb
- Seats: 2
- Landing gear: fixed
- Engine: Rolls Royce 250-C20C (T6 (turboshaft); 1,760 hours total
The flight
- Departed from: Stratford CA at 7:00 pm
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 190° at 4 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 88°F (31°C), dew point 52°F (11°C)
- Altimeter: 29.91 inHg
- Observation at 11:53 am from KHJO, 12 miles away
Weather report (METAR): KHJO 091853Z AUTO 19004KT 10SM CLR 31/11 A2991 RMK AO2 SLP129 T03060106
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 WPR23LA313.