Bell 47G-3B-2 accident near Los Banos, California, August 14, 2011
On August 14, 2011 at about 7:45 pm local time, a Bell 47G-3B-2 (helicopter), registered N475AL, was substantially damaged in an accident during takeoff near Los Banos, 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 pilot’s inadequate preflight, and contamination of both the engine compressor section and the main rotor blades, which resulted in reduced performance of the engine and rotor system.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 14, 2011 · about 7:45 pm local time
- Place
- Los Banos, California · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Bell 47G-3B-2 · all 47G-3B-2s on the register
- Registration
- N475AL · registry record · serial 6675
- Damage
- Substantial damage
- Flight
- Aerial application (crop spraying) flight · agricultural flying rules (Part 137)
The NTSB's narrative final · quoted from the NTSB record
During an agricultural application flight, the helicopter had just departed from the elevated landing pad when it experienced a loss of lift, which the pilot thought was a loss of engine power. The pilot attempted to arrest the descent but was unsuccessful before the helicopter hit the trees. Examination of the engine revealed no pre-impact mechanical malfunctions that would have prevented normal operations. Postaccident examination noted that the compressor vanes and both main rotor blades were layered with a substance that had the consistency of peanut butter. As a result of the contamination, the compressor would not operate at its optimum level, which affected the power output performance of the engine. The material on the main rotor blades would also have affected the helicopter’s lift performance. The examination did not reveal what the substance was, but the airplane flew through agricultural products, which may have led to the substance building up on the blades and compressor over time. Had the pilot done a preflight inspection, he may have noticed the contamination in the engine compressor section and the main rotor blades. Because the helicopter was departing from an elevated land platform, after liftoff, the helicopter was immediately out of ground effect, which resulted in an immediate descent that the pilot was unable to arrest.
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
- Preflight or dispatch event during prior to flight
- Collision during takeoff/land during takeoff defining event
The NTSB's findings
- cause Personnel issues › Task performance › Inspection › Preflight inspection › Pilot
- cause Aircraft › Aircraft propeller/rotor › Main rotor system › Main rotor blade system › Not serviced/maintained
- cause Aircraft › Aircraft power plant › Engine (turbine/turboprop) › Compressor section › Not serviced/maintained
Pilot
- Certificate: flight instructor, commercial pilot
- Ratings: instructor: helicopter; rotorcraft: helicopter
- Flight time: 1,600 hours in all; 100 in this make and model; 200 in the last 90 days; 90 in the last 30 days; 1,540 as pilot in command; 650 on instruments
- Last flight review: August 10, 2010
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 8,034 hours
- Last inspection: annual inspection; 83 hours since
- Maximum gross weight: 2,950 lb
- Seats: 3
- Landing gear: fixed
- Engine: Allison 250 SERIES (turboshaft); 0 hours total
The flight
- Departed from: Los Banos CA at 7:45 pm
- Destination: Los Banos CA
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 330° at 17 knots, gusting 23
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 93°F (34°C), dew point 41°F (5°C)
- Altimeter: 29.87 inHg
- Observation at 7:53 pm from MCE, 15 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.
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.