Bell OH 58A accident near Brawley, California, July 2, 2016
On July 2, 2016 at about 9:30 am local time, a 1970 Bell OH 58A (helicopter), registered N6251G, was substantially damaged in an accident during maneuvering (low-alt flying) near Brawley, California. 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).
The NTSB's probable cause their words, unchanged
The engine's degraded performance due to excessive wear of the engine bleed valve, which prevented it from closing during the accident flight. Contributing to the accident was the operator's failure to overhaul the bleed valve within the manufacturer-recommended interval.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 2, 2016 · about 9:30 am local time
- Place
- Brawley, California · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Bell OH 58A NO SERIES, built 1970 · all OH 58As on the register
- Registration
- N6251G · registry record · serial 70-15444
- 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 commercial pilot reported that, after departing for the agricultural flight, he maneuvered the helicopter to line up with the field to be sprayed. Shortly after lining up with the field, the engine started to surge, and he saw the torque meter needle "bouncing rapidly." The pilot initiated a precautionary landing to an open field. The helicopter landed hard, which resulted in substantial damage to the tailboom and tail rotor drive shaft. A test run of the engine revealed that the bleed valve did not close at any speed and that the engine produced less than 250 horsepower (hp). The bleed valve was disassembled, and the diaphragm was found to have several holes and cracks, and the poppet valve located in the bleed valve assembly had radial play, consistent with worn bushings. The damaged bleed valve was replaced with an overhauled bleed valve, and during a subsequent test run, the engine produced about 380 hp, which is about 7% below minimum allowable power for a serviceable engine. Given these results, the excessive wear of the bleed valve likely prevented it from closing during the accident flight, which resulted in the engine's degraded performance. According to the operator, the compressor, turbine, and bleed valve assemblies were overhauled about 2 years before the accident and then reassembled on the engine. The engine had operated about 766 hours since overhaul at the time of the accident. The engine manufacturer reported that the bleed valve assembly should be overhauled every 1,500 hours. No component log cards or historical information for the bleed valve was located during the investigation. According to the engine manufacturer, the bleed valve exhibited wear that was not consistent with a bleed valve with comparable service time. Therefore, it is likely that the bleed valve was likely not overhauled 2 years before the accident as reported by the operator and that it was beyond the overhaul period of 1,500 hours, which resulted in the observed wear that ultimately prevented the engine from producing sufficient power during takeoff.
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 (low-alt flying) defining event
- Off-field or emergency landing during landing
- Hard landing during landing
The NTSB's findings
- cause Aircraft › Aircraft power plant › Engine bleed air system › Compressor bleed valve › Damaged/degraded
- cause Aircraft › Aircraft handling/service › Maintenance/inspections › Scheduled maint checks › Not serviced/maintained
- cause Personnel issues › Task performance › Maintenance › Scheduled/routine maintenance › Other/unknown
Pilot
- Certificate: commercial pilot
- Ratings: single-engine land; instrument: airplane; rotorcraft: helicopter
- Flight time: 7,000 hours in all; 1,500 in this make and model; 150 in the last 90 days; 50 in the last 30 days; 7,000 as pilot in command
- Last flight review: May 30, 2015
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: rgt
- Injury: no injuries
The aircraft
- Airframe total time: 13,688 hours
- Last inspection: 100-hour inspection, June 15, 2016; 74 hours since
- Maximum gross weight: 3,000 lb
- Seats: 1
- Landing gear: fixed
- Engine: Ama/Expr UNKNOWN ENG (turboshaft); 5,618 hours total
- Operator: Farm Aviation INC
The flight
- Departed from: Brawley CA
- Destination: Brawley CA
- Flight plan: none
Weather at the time
- Light: night
- Wind: from 080° at 9 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 84°F (29°C), dew point 64°F (18°C)
- Altimeter: 29.77 inHg
- Observation at 8:53 am from KIPL, 10 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Other NTSB records under N6251G the same tail number, which may have belonged to a different aircraft at the time
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.