Bell 206B accident near Clarkson Valley, Missouri, October 15, 2010
On October 15, 2010 at about 4:10 pm local time, a Bell 206B (helicopter), registered N96MP, was substantially damaged in an accident during enroute (cruise) near Clarkson Valley, Missouri. It was a public-use flight (state) under general aviation rules (Part 91). 1 person was killed. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The total loss of engine power due to fuel exhaustion, which resulted from the pilot's inadequate preflight planning and decision-making, and his improper control inputs following the loss of engine power, which resulted in mast bumping and separation of the main rotor. Contributing to the accident was the pilot's improper judgment in acting as a pilot with disqualifying medical conditions.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- October 15, 2010 · about 4:10 pm local time
- Place
- Clarkson Valley, Missouri · map
- Type
- Accident
- Injuries
- 1 person was killed.
- Weather
- visual conditions (good weather)
- Aircraft
- Bell 206B · all 206Bs on the register
- Registration
- N96MP · no longer on the register · serial 3377
- Damage
- Substantial damage
- Flight
- Public-use flight (state) · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
During the flight that preceded the accident flight, the pilot stated to one of the two officers aboard the helicopter that he would not be able to fly for as long as normal because he needed to obtain fuel. Upon completion of the observation flight, the pilot returned to the police department and shut down the helicopter to allow the two officers to exit. The pilot then restarted the helicopter and departed en route to an airport where he could refuel the helicopter. A witness near the accident site stated that he heard the helicopter’s engine sputter and stop and saw the main rotor separate from the helicopter. The helicopter entered an uncontrolled descent and impacted terrain. Postaccident examination of the helicopter revealed that there was no usable fuel on board and that the main rotor mast separated as a result of overload due to mast bumping (main rotor hub to rotor mast contact). No preimpact mechanical anomalies that would have precluded normal operation of the helicopter were noted. Mast bumping typically results from a low-G flight condition caused by the pilot pushing the cyclic control forward abruptly from either straight-and-level flight or after a climb. Pushing the cyclic forward abruptly is contrary to the appropriate actions for entering an autorotation, which are lowering the collective pitch control to the full down position, adding antitorque pedal as needed to maintain heading, and applying cyclic as needed to maintain proper airspeed. Review of the pilot’s medical records indicated that he had a history of depression, anxiety, and obstructive sleep apnea. Each of these conditions had been documented and treated since 2007, and none were reported to the Federal Aviation Administration (FAA) on the pilot’s airman medical application in 2010 or earlier. Any of these conditions may have disqualified the pilot from obtaining an airman’s medical certificate. Postmortem toxicological testing indicated that the pilot was taking alprazolam, an anti-anxiety medication, and venlafaxine, an anti-depressant. Alprazolam is one of a class of drugs which may worsen obstructive sleep apnea, and venlafaxine can cause fatigue and dizziness. The fact that the blood level of venlafaxine found was higher than normal therapeutic levels makes it more likely that the side effect of dizziness occurred and impaired the pilot’s performance.
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
- Fuel exhaustion during enroute (cruise) defining event
- Autorotation Mast bumping
- AC during autorotation Part(s) separation from
- Autorotation Loss of control in flight
- Collision with terrain or object (not controlled flight into terrain) during uncontrolled descent
The NTSB's findings
- cause Personnel issues › Task performance › Planning/preparation › (general) › Pilot
- cause Aircraft › Fluids/misc hardware › Fluids › Fuel › Fluid level
- cause Personnel issues › Action/decision › Action › Incorrect action performance › Pilot
- factor Personnel issues › Physical › (general) › (general) › Pilot
Pilot
- Certificate: private
- Ratings: multi-engine land; single-engine land; instrument: airplane; rotorcraft: helicopter
- Flight time: 2,607 hours in all; 820 in this make and model; 141 in the last 90 days; 38 in the last 30 days; 2,503 as pilot in command
- Last flight review: April 7, 2009
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: rgt
- Injury: fatal
The aircraft
- Airframe total time: 11,254 hours
- Last inspection: 100-hour inspection, May 7, 2010; 69 hours since
- Maximum gross weight: 3,200 lb
- Seats: 5
- Landing gear: fixed
- Engine: Allison 250-C20B (turboshaft); 0 hours total
The flight
- Departed from: Arnold MO at 3:53 pm
- Destination: SUS St. Louis MO
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 350° at 3 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 63°F (17°C), dew point 37°F (3°C)
- Altimeter: 30.12 inHg
- Observation at 3:54 pm from SUS, 3 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.