Hughes 369D accident near Kooskia, Idaho, January 8, 2010
On January 8, 2010 at about 7:20 pm local time, a Hughes 369D (helicopter), registered N500LW, was substantially damaged in an accident during maneuvering near Kooskia, Idaho. It was a public-use flight (state) under public-use (government) rules. 3 people were seriously injured. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
A complete loss of engine power due to the failure of the No. 2 bearing, which was precipitated by electrical arcing that occurred at an unknown time prior to the accident flight.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- January 8, 2010 · about 7:20 pm local time
- Place
- Kooskia, Idaho · map
- Type
- Accident
- Injuries
- 3 people were seriously injured.
- Weather
- visual conditions (good weather)
- Aircraft
- Hughes 369D · all 369Ds on the register
- Registration
- N500LW · no longer on the register · serial 470120D
- Damage
- Substantial damage
- Flight
- Public-use flight (state) · public-use (government) rules
The NTSB's narrative final · quoted from the NTSB record
The pilot was maneuvering the helicopter for a wolf-capturing mission above rugged terrain densely populated by trees. As the pilot maneuvered the helicopter in a hover about 300 to 400 feet above the ground, a loud "bang" emitted from the engine compartment, followed by a loss of engine power and slight vibration. With the low rpm light illuminated, the pilot lowered the collective and entered an autorotation; the helicopter landed hard. A postaccident examination of the engine revealed metal particles adhering to both engine chip detector plugs. Disassembly of the engine revealed that the No. 2 bearing failed. The damage identified on the bearing’s outer race was consistent with electrical arcing. The extensive wear and mechanical damage to the bearing raceways and the bearing balls precluded the identification of arcing damage on the raceways and ball surfaces. However, the arcing damage found was sufficient to precipitate a bearing failure such as was found on accident engine. The bearings are a common source of electrical grounding between the case of a turbine engine and the rotating components. Hence, bearings are a probable location of electrical arcing if conditions are sufficient. Although the exact source of electrical arc could not be determined for the helicopter, it is possible that a lightning strike or stray electrical current could have precipitated such damage. The metal splatter deposits present on the oil slinger surfaces were approximately aligned in the same direction suggesting that the arcing associated with the oil slinger occurred when the engine compressor was not rotating. Although the chip detector caution indicator was found to be inoperative, it is unknown whether it would have alerted the pilot soon enough to the impending engine failure for him to execute a precautionary landing.
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 maneuvering defining event
- Off-field or emergency landing during emergency descent
- Autorotation Hard landing
The NTSB's findings
- cause Aircraft › Aircraft power plant › Engine (turbine/turboprop) › (general) › Failure
Pilot
- Certificate: flight instructor, commercial pilot
- Ratings: multi-engine land; single-engine land; instructor: airplane single-engine; instructor: helicopter; instrument: airplane; rotorcraft: helicopter
- Flight time: 18,000 hours in all; 1,600 in this make and model; 100 in the last 90 days; 70 in the last 30 days; 17,900 as pilot in command; 1,000 on instruments
- Last flight review: March 30, 2009
- Medical certificate: Class 2 (with waivers/limitations)
- Seat: left
- Injury: serious injuries
The aircraft
- Airframe total time: 13,167 hours
- Last inspection: 100-hour inspection, December 30, 2009; 27 hours since
- Maximum gross weight: 3,000 lb
- Seats: 4
- Landing gear: fixed
- Engine: Rolls-Royce 250C20B (turboshaft); 0 hours total
The flight
- Departed from: Kooskia ID at 5:55 pm
- Destination: KS82 Kooskia ID
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 080° at 10 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 30°F (-1°C), dew point 19°F (-7°C)
- Altimeter: 30.34 inHg
- Observation at 1:56 am from KLWS, 45 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 | |||
| Passengers | 2 |
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.