Hughes 369D accident near Taholah, Washington, December 8, 1998
On December 8, 1998 at about 7:45 pm local time, a Hughes 369D (helicopter), registered N1096L, was substantially damaged in an accident near Taholah, Washington. It was an other work-use flight under external-load helicopter rules (Part 133). 1 person had minor injuries. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
Turbine wheel failure as the result of a low-cycle fatigue crack that initiated in a beyond-limits grinding gouge. Factors include improper maintenance by unknown parties and tree stumps that prohibited a successful emergency landing.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- December 8, 1998 · about 7:45 pm local time
- Place
- Taholah, Washington · map
- Type
- Accident
- Injuries
- 1 person had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Hughes 369D · all 369Ds on the register
- Registration
- N1096L · no longer on the register · serial 800789
- Damage
- Substantial damage
- Flight
- Other work-use flight · external-load helicopter rules (Part 133)
The NTSB's narrative final · quoted from the NTSB record
While conducting external load operations the helicopter sustained substantial damaged after a loss of engine power, autorotation, and forced landing. A witness reported hearing a loud bang, followed by the engine spooling down. The witness also reported seeing smoke coming from the engine as the helicopter descended through the trees, landing hard on a tree stump under the pilot's seat area. Postaccident inspection of the turbine engine revealed excessive blending in the web of the first stage turbine wheel. Within the blending, a notch exhibited a radius sharper than allowed by blend limits, which the manufacturer' metallurgists believed to have been created by a hand-held grinder. It could not be determined whether the manufacturer of the turbine wheel or an overhaul facility made the subject grinding marks.
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: 22,000 hours in all; 12,000 in this make and model; 250 in the last 90 days; 21,000 as pilot in command
- Medical certificate: Class 2 (valid medical--no waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 5,582 hours
- Last inspection: annual inspection, November 5, 1998; 84 hours since
- Maximum gross weight: 3,500 lb
- Seats: 5
- Landing gear: fixed
- Engine: Allison 250-C20B (turboshaft); 0 hours total
The flight
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Wind: at 5 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 45°F (7°C), dew point 37°F (3°C)
- Altimeter: 30.00 inHg
- Observation at 7:53 pm from UIL, 30 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.
Other NTSB records under N1096L 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.