Eurocopter AS 350 B2 accident near Riverside, California, February 24, 2011
On February 24, 2011, a Eurocopter AS 350 B2 (helicopter), registered N965SD, was substantially damaged in an accident during takeoff near Riverside, California (March Air Reserve Base airport). It was a public-use flight (local) under public-use (government) rules. 2 people had minor injuries. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The failure of both pilots to follow proper procedures during a simulated hydraulic emergency that resulted in a loss of helicopter control. Contributing to the accident was the flight instructor’s delayed remedial action.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- February 24, 2011
- Place
- Riverside, California · March Air Reserve Base · map
- Type
- Accident
- Injuries
- 2 people had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Eurocopter AS 350 B2 · all AS 350 B2s on the register
- Registration
- N965SD · no longer on the register · serial 3626
- Damage
- Substantial damage
- Flight
- Public-use flight (local) · public-use (government) rules
The NTSB's narrative final · quoted from the NTSB record
The flight instructor had briefed the flying pilot that he wanted him to perform a maximum performance takeoff simulating a 20- to 25-foot obstacle and that he was going to simulate a hydraulic failure during the maneuver by activating the hydraulic test switch. Prior to performing the maneuver, the pilot confirmed with the instructor that once the hydraulic failure warning activated he would accelerate to 40 knots before activating the hydraulic isolation switch. The instructor would need to reset the hydraulic test switch prior to the pilot activating the hydraulic isolation switch. After the briefing, the pilot initiated the maximum performance takeoff, and as the helicopter attained 20-25 feet, the instructor activated the hydraulic test switch. The pilot stated that as soon as the test switch was activated, he could no longer input right pedal because the control forces were too great. The helicopter began to yaw to the left, and the pilot then activated the hydraulic isolation switch because he thought the helicopter would be more controllable. The pilot did not consider that the hydraulic fluid had been evacuated from both the tail rotor accumulator and the yaw load compensator actuator due to the activation of the hydraulic test switch by the instructor, and the test switch had not yet been reset. As a result, the hydraulic boost from the normally closed yaw load compensator system was unavailable. The helicopter continued to yaw to the left and developed into a spin about its vertical axis. The instructor told the pilot to “fly the helicopter” and was hoping the pilot would recover from the loss of control condition. The pilot attempted to recover by following the direction of the nose of the helicopter to try to gain airspeed. The instructor attempted to intercede by inputting right cyclic, but since the pilot was applying left cyclic, the cyclic inputs were ineffective. The helicopter spun around several times before impacting the taxiway. According to the training procedure for a loss of hydraulic pressure, the instructor should have reset the hydraulic test switch prior to the pilot activating the hydraulic isolation switch. This flight manual specific sequence of switch selections and corresponding actions when simulating a hydraulic system failure were not followed by the pilots. Postaccident examination of the helicopter systems, including the hydraulic system, revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation.
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
- Simulated/training event during takeoff
- Loss of control in flight during takeoff defining event
The NTSB's findings
- cause Personnel issues › Action/decision › Action › Incorrect action sequence › Pilot
- factor Personnel issues › Action/decision › Action › Delayed action › Instructor/check pilot
- cause Aircraft › Aircraft systems › Hydraulic power system › (general) › Incorrect use/operation
- cause Personnel issues › Action/decision › Action › Incorrect action sequence › Instructor/check pilot
Flight instructor
- Certificate: flight instructor, commercial pilot
- Ratings: multi-engine land; single-engine land; instructor: airplane multi-engine; instructor: airplane single-engine; instructor: helicopter; instrument: airplane; instrument: helicopter; rotorcraft: helicopter
- Flight time: 6,728 hours in all; 4,276 in this make and model; 43 in the last 90 days; 19 in the last 30 days; 6,642 as pilot in command; 362 on instruments
- Last flight review: February 19, 2010
- Medical certificate: Class 1 (with waivers/limitations)
- Seat: left
- Injury: minor injuries
Pilot
- Certificate: private
- Ratings: single-engine land; rotorcraft: helicopter
- Flight time: 245 hours in all; 73 in this make and model; 61 in the last 90 days; 45 in the last 30 days; 155 as pilot in command
- Last flight review: July 3, 2010
- Medical certificate: Class 1 (without waivers/limitations)
- Seat: rgt
- Injury: minor injuries
The aircraft
- Airframe total time: 6,348 hours
- Last inspection: 100-hour inspection, February 2, 2011
- Maximum gross weight: 4,961 lb
- Seats: 6
- Landing gear: fixed
- Engine: Turbomeca ARRIEL 1D1 (turboshaft); 0 hours total
- Operator: County Of Los Angeles
The flight
- Departed from: RIV Riverside CA
- Destination: RIV Riverside CA
- Flight plan: none
- Runway 30, 3,059 ft by 10 ft
- A second pilot was aboard
Weather at the time
- Light: daylight
- Visibility: 5 statute miles
- Sky: scat
- Temperature: 41°F (5°C), dew point 39°F (4°C)
- Altimeter: 30.02 inHg
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 2 |
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.