Robinson Helicopter R44 accident near Torrance, California, September 3, 2009
On September 3, 2009 at about 8:00 pm local time, a Robinson Helicopter R44, registered N8361X, was substantially damaged in an accident near Torrance, California (Zamperini Field Airport). It was a personal flight under general aviation rules (Part 91). 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
A main rotor overspeed due to the pilot’s failure to maintain rotor RPM within allowable limits during a practice autorotation.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- September 3, 2009 · about 8:00 pm local time
- Place
- Torrance, California · Zamperini Field Airport · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Robinson Helicopter R44 · all R44s on the register
- Registration
- N8361X · registry record · serial 0431
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot reported that he initiated a practice autorotation to a paved helipad. As the helicopter descended through about 100 feet agl, the pilot initiated a recovery by “slowly rolling on throttle.” The pilot stated that as the helicopter descended, he noticed the rotor RPM “increase quickly.” Subsequently,the helicopter landed on the helipad uneventfully. Post accident examination of the helicopter revealed that the tail boom of the helicopter was structurally damaged, and the tail rotor drive shaft was bent and separated in multiple locations. The drive shaft exhibited scoring around the circumference at regularly spaced intervals on the shaft. The damper assembly was heavily damaged, and the intermediate flex coupling assembly was damaged. According to the helicopter’s manufacturer, this damage to the tail rotor drive shaft is indicative of a rotor over speed to at least 134%. No pre-accident mechanical anomalies were noted with the engine or airframe 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
- Autorotation Miscellaneous/other defining event
The NTSB's findings
- cause Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Prop/rotor parameters › Capability exceeded
- cause Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Prop/rotor parameters › Not attained/maintained
- cause Personnel issues › Task performance › Use of equip/info › Use of equip/system › Pilot
Pilot
- Certificate: flight instructor, commercial pilot
- Ratings: single-engine land; instructor: helicopter; instructor: instrument helicopter; instrument: airplane; instrument: helicopter; rotorcraft: helicopter
- Flight time: 911 hours in all; 60 in this make and model; 71 in the last 90 days; 811 as pilot in command; 8 on instruments
- Last flight review: February 18, 2009
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: rgt
- Injury: no injuries
The aircraft
- Airframe total time: 1,067 hours
- Last inspection: inspection type not recorded
- Maximum gross weight: 2,400 lb
- Seats: 4
- Landing gear: fixed
- Engine: Lycoming O-540-F1B5 (piston); 0 hours total
- Operator: Universal Air Academy
The flight
- Departed from: POA La Verne CA at 7:45 pm
- Destination: TOA Torrance CA
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 300° at 14 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 86°F (30°C), dew point 61°F (16°C)
- Altimeter: 29.87 inHg
- Observation at 8:48 pm from TOA
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.