Bell 205 accident near Tehachapi, California, September 4, 2011
On September 4, 2011 at about 10:00 pm local time, a Bell 205 (helicopter), registered N205WW, was substantially damaged in an accident during maneuvering (low-alt flying) near Tehachapi, California. It was a public-use flight (local) under external-load helicopter rules (Part 133). 1 person had minor injuries. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The pilot's inability to adequately execute an emergency autorotation due to the flight's low altitude during external load operations, which resulted in a hard landing. Contributing to the accident was a torsionally overstressed tachometer shaft, which sent erroneous engine rpm readings to the cockpit.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- September 4, 2011 · about 10:00 pm local time
- Place
- Tehachapi, California · map
- Type
- Accident
- Injuries
- 1 person had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Bell 205 A1 · all 205s on the register
- Registration
- N205WW · registry record · serial 30329
- Damage
- Substantial damage
- Flight
- Public-use flight (local) · external-load helicopter rules (Part 133)
The NTSB's narrative final · quoted from the NTSB record
During an external load operation to drop water on a fire, the helicopter was about 100 feet above ground level at 10 knots when the engine rpm light illuminated and the low rotor rpm horn sounded. The emergency procedures section of the flight manual states that in the event of an engine failure or low rpm, a red light will illuminate and an audio signal will sound when the audio switch is in the AUDIO position. The flight manual instructs the pilot to immediately execute an autorotative descent. The pilot released the water, and made a left-pedal turn to exit the canyon and move away from the fire. He checked his engine rotor rpm gauge and saw that the needles had split: the rotor needle was at the 4-5 o'clock position, and the engine needle was at the 6-o'clock position, which he stated indicated maximum rpm. He maneuvered to establish an autorotation into a landing zone. The helicopter sustained substantial damage to the airframe and tail boom as the result of a hard landing, which collapsed the landing skid. Postaccident examination discovered that the N2 tachometer drive shaft was sheered as a result of torsional overstress. The N2 tachometer drive delivers engine rpm readings to the cockpit engine tachometer; failure of the N2 tachometer drive would send erroneous engine rpm readings to the cockpit. Accordingly, the pilot's instruments indicated that there was an engine overspeed, but the warning lights and audio were indicating a low power condition. The pilot elected to perform an autorotative landing in accordance with the flight manual instructions for a low rotor rpm.
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
- Powerplant sys/comp malf/fail during maneuvering (low-alt flying) defining event
The NTSB's findings
- factor Aircraft › Aircraft power plant › Engine indicating system › Power indicating system › Malfunction
- cause Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Landing flare › Incorrect use/operation
- cause Personnel issues › Task performance › Use of equip/info › Aircraft control › Pilot
Pilot
- Certificate: commercial pilot, private
- Ratings: single-engine land; instructor: helicopter; rotorcraft: helicopter
- Flight time: 9,304 hours in all; 865 in this make and model; 138 in the last 90 days; 37 in the last 30 days; 9,103 as pilot in command
- Medical certificate: Class 2 (with waivers/limitations)
- Seat: left
- Injury: minor injuries
The aircraft
- Airframe total time: 3,560 hours
- Last inspection: 100-hour inspection, August 31, 2011; 89 hours since
- Maximum gross weight: 10,500 lb
- Seats: 11
- Landing gear: fixed
- Engine: Honeywell T5317B (turboshaft); 0 hours total
- Operator: Kern County
The flight
- Departed from: Tehachapi CA at 8:55 pm
- Destination: Tehachapi CA
Weather at the time
- Light: daylight
- Wind: from 310° at 13 knots, gusting 19
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 86°F (30°C), dew point 28°F (-2°C)
- Altimeter: 30.03 inHg
- Observation at 9:55 pm from KTSP
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.