Aerospatiale AS350D accident near Webb, Idaho, August 13, 2003
On August 13, 2003 at about 9:50 pm local time, a Aerospatiale AS350D (helicopter), registered N57731, was substantially damaged in an accident near Webb, Idaho. It was an other work-use flight under external-load helicopter rules (Part 133). 1 person was seriously injured. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
An over temperature condition within the gas generator turbine which led to first stage turbine blade fatigue as well as first stage blade track warping and consequent blade tip rub. The fatigue and blade tip rub ultimately led to blade separation and failure of the engine. Contributing factors were the out of calibration condition of the turbine outlet temperature gauge and the non-operational engine CHIP warning light system. An additional factor was insufficient rotor RPM while conducting an autorotation.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 13, 2003 · about 9:50 pm local time
- Place
- Webb, Idaho · map
- Type
- Accident
- Injuries
- 1 person was seriously injured.
- Weather
- visual conditions (good weather)
- Aircraft
- Aerospatiale AS350D · all AS350Ds on the register
- Registration
- N57731 · no longer on the register · serial 1434
- Damage
- Substantial damage
- Flight
- Other work-use flight · external-load helicopter rules (Part 133)
The NTSB's narrative final · quoted from the NTSB record
The pilot had just maneuvered the helicopter for a water pickup for firefighting and was at an altitude of 100-150 feet above ground transitioning to forward flight (outside the height-velocity envelope) when the engine failed. He executed an autorotation to a hard landing as rotor speed bled off. Post accident examination of the engine revealed all the airfoils of the first stage turbine wheel were fractured/damaged and many of the fracture surfaces exhibited features indicative of fatigue progression. Fluorescent penetrant inspection revealed multiple cracks extending onto the rim faces and radial sectioning of several of the stage one turbine airfoils revealed intergranular cracks within the airfoils as well as cracks in the rim area consistent with exposure to temperature spikes and/or elevated operating temperatures. Examination of the second stage turbine nozzle assembly revealed evidence of both thermal distress and mechanical damage and the first stage blade track exhibited damage and deformation throughout its circumference. The diameter and run-out of both the first stage and second stage blade tracks revealed an out of round (warped) condition. Testing of the ToT gauge revealed an out of calibration condition between true input temperature and the temperature displayed on the gauge. The disparity increased as true temperature increased with the gauge reading on the low side (lower than true operating temperatures). Post accident examination revealed metal particulates bridging the contacts of the engine chip light plug. Testing of the warning system revealed a discontinuity within the airframe which prevented the chip light from operating.
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: commercial pilot
- Ratings: rotorcraft: helicopter
- Flight time: 4,000 hours in all; 100 in this make and model; 100 in the last 90 days; 45 in the last 30 days; 3,800 as pilot in command
- Last flight review: July 3, 2003
- Medical certificate: Class 2 (valid medical--no waivers/lim.)
- Seat: rgt
- Injury: serious injuries
The aircraft
- Airframe total time: 7,154.9 hours
- Last inspection: 100-hour inspection, June 29, 2003; 51 hours since
- Maximum gross weight: 4,190 lb
- Seats: 6
- Landing gear: fixed
- Engine: Rolls-Royce (Allison) 250-C30M (turboshaft); 0 hours total
The flight
- Departed from: S89 Craigmont ID at 9:30 pm
Weather at the time
- Light: daylight
- Wind: from 290° at 8 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 90°F (32°C), dew point 37°F (3°C)
- Altimeter: 30.01 inHg
- Observation at 9:56 pm from LWS, 8 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| 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.