Eurocopter AS350B3 accident near Sierra Vista, Arizona, November 2, 2004
On November 2, 2004 at about 2:31 pm local time, a Eurocopter AS350B3 (helicopter), registered N106LN, was substantially damaged in an accident near Sierra Vista, Arizona (Sierra Vista Hosp airport). It was a positioning flight under general aviation rules (Part 91). No one was hurt; 3 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
An inconsistency between the engines' two N2 sensor signals caused the fuel control to enter a fixed mode, which limited the power available. Contributing to the accident was the lack of altitude and airspeed available to give the pilot time to select a landing zone, disengage the flight notch, and exercise manual control of the engine after the illumination of the red 'GOV' light.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- November 2, 2004 · about 2:31 pm local time
- Place
- Sierra Vista, Arizona · Sierra Vista Hosp · map
- Type
- Accident
- Injuries
- No one was hurt; 3 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Eurocopter AS350B3 · all AS350B3s on the register
- Registration
- N106LN · no longer on the register · serial 3261
- Damage
- Substantial damage
- Flight
- Positioning flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The helicopter experienced a partial loss of power during the transition from an out of ground effect hover to forward flight, and collided with the ground in a parking lot. About 10 seconds after the transition to forward flight, at 35 knots and between 150 to 200 feet above ground level, the pilot sensed the engine turbine start to spool down towards idle. He saw a red 'GOV' light illuminated on the instrument panel. The pilot did not disengage the flight notch on the collective twist grip to manually control the fuel flow to the engine and proceeded to fly the helicopter about 1/8 mile towards the parking lot, working the collective to try to keep the helicopter above the trees and the roofs of the houses. He used all the available rotor rpm in an attempt to arrest the landing. The helicopter landed hard, collapsing the landing skids, and the ship slid about 100 feet. After the helicopter came to rest, the main rotor was still rotating at a slower rpm, and the engine was operating at what seemed like a low idle speed. The partial loss of engine power was initiated by an inconsistency of greater than 3 percent between the two N2 (free turbine speed) sensors on the engine. This inconsistency resulted in the fuel control entering a fixed mode that freezes the fuel flow at the level it was at when the inconsistency was detected, and the illumination of a red 'GOV' light in the cockpit. The power required for forward flight is less than the power required to hover. The fixed fuel flow to the engine provided insufficient power to fly and land the helicopter at speeds below 35 knots, which resulted in low rotor rpm and a high rate of decent prior to the hard landing. In the event of a red 'GOV' light the pilot is to disengage the flight notch and control the fuel manually with the collective twist grip, which would allow the pilot to regain the full power range of the engine. At an altitude of 150 to 200 feet and airspeed of 35 knots, the pilot was operating in the avoidance zone of the documented height-velocity diagram, and therefore, may not have had enough time to fully respond to the partial loss of power by selecting an emergency landing site, disengaging the twist grip flight notch, and exercising manual control of the engine.
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
Pilot
- Certificate: flight instructor, commercial pilot
- Ratings: instructor: helicopter; instructor: instrument helicopter; instrument: helicopter; rotorcraft: helicopter
- Flight time: 9,992 hours in all; 350 in this make and model; 70 in the last 90 days; 25 in the last 30 days; 9,867 as pilot in command; 686 on instruments
- Last flight review: October 1, 2004
- Medical certificate: Class 2
- Seat: rgt
- Injury: no injuries
The aircraft
- Airframe total time: 3,163.8 hours
- Last inspection: 100-hour inspection, November 1, 2004; 0 hours since
- Maximum gross weight: 4,961 lb
- Seats: 4
- Landing gear: fixed
- Engine: Turbomeca Arriel 2B (turboshaft); 0 hours total
The flight
- Departed from: AZ89 Sierra Vista AZ at 2:30 pm
- Destination: Portal AZ
Weather at the time
- Light: daylight
- Wind: at 4 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 34°F (1°C), dew point 46°F (8°C)
- Altimeter: 30.30 inHg
- Observation at 1:55 pm from KFHU
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 3 |
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.
Other NTSB records under N106LN the same tail number, which may have belonged to a different aircraft at the time
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.