S.N.I.A.S. AS-350B ECUREUIL accident near Hamilton, Montana, July 1, 2013
On July 1, 2013 at about 5:00 pm local time, a 1985 S.N.I.A.S. AS-350B ECUREUIL (helicopter), registered N989WC, was substantially damaged in an accident during enroute (cruise) near Hamilton, Montana (Hamilton 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
The loss of engine power during cruise flight due to the fatigue failure of a pneumatic fuel controller pipe. Also causal was maintenance personnel’s failure to adequately maintain the pipe and replace it with a thicker type.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 1, 2013 · about 5:00 pm local time
- Place
- Hamilton, Montana · Hamilton · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- S.N.I.A.S. AS-350B ECUREUIL, built 1985
- Registration
- N989WC · no longer on the register · serial 1923
- 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, about 20 minutes after departure, the helicopter lost all engine power during cruise flight. The pilot performed an autorotation into a small forest clearing. During the landing sequence, the helicopter sustained substantial damage. Examination of the engine revealed that the pneumatic fuel controller (P2) pipe that delivered air pressure from the centrifugal compressor to the fuel control unit (FCU) had separated at the FCU fitting. The P2 pipe's failure allowed ambient air pressure to enter the line and resulted in the FCU commanding the engine to spool down to ground idle speed. The pipe exhibited deformation due to bending damage and signatures indicating that it was making contact with its union fitting at the FCU. The P2 pipe was a thin-walled type, which the engine manufacturer had recommended be replaced with a thicker version 29 years previously. Further, the engine manufacturer had issued multiple service letters advising maintenance personnel of the correct procedures for fitting, inspecting, and maintaining such air lines. The pipe's fracture surfaces at the separation point exhibited signatures consistent with fatigue as a result of noncompliance with the manufacturer's recommendations.
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
- Loss of engine power (total) during enroute (cruise) defining event
- Autorotation Off-field or emergency landing
- Hard landing during landing (flare/touchdown)
The NTSB's findings
- cause Aircraft › Aircraft power plant › Engine fuel and control › Fuel controlling system › Fatigue/wear/corrosion
- cause Personnel issues › Task performance › Maintenance › Replacement › Maintenance personnel
- cause Personnel issues › Task performance › Maintenance › Installation › Maintenance personnel
Pilot
- Certificate: commercial pilot
- Ratings: rotorcraft: helicopter
- Flight time: 388.7 hours in all; 84.5 in this make and model
- Last flight review: October 25, 2012
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: rgt
- Injury: no injuries
The aircraft
- Airframe total time: 10,000 hours
- Last inspection: continuous airworthiness programme, April 30, 2013; 59 hours since
- Maximum gross weight: 4,300 lb
- Seats: 6
- Landing gear: fixed
- Engine: Turbomeca Arriel 1B (turboshaft); 9,922 hours total
The flight
- Departed from: 6S5 Hamilton MT at 4:40 pm
- Destination: U05 Philipsburg MT
Weather at the time
- Light: daylight
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 79°F (26°C), dew point 57°F (14°C)
- Altimeter: 30.15 inHg
- Observation at 4:53 pm from KMSO, 41 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.