Kaman K-1200 accident near Dayville, Oregon, March 17, 2006
On March 17, 2006 at about 5:35 pm local time, a Kaman K-1200 (helicopter), registered N263KA, was substantially damaged in an accident near Dayville, Oregon. It was an other work-use flight under external-load helicopter rules (Part 133). 1 person was killed. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The improper overhaul of the reduction gear box assembly and improper installation of the N1 seal and nut assembly lockcup by maintenance personnel, which resulted in failure of the reduction gear box and a total loss of engine power. A contributing factor was the pilot's failure to maintain adequate rotor rpm following the power loss, which resulted in an uncontrolled descent to ground impact.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- March 17, 2006 · about 5:35 pm local time
- Place
- Dayville, Oregon · map
- Type
- Accident
- Injuries
- 1 person was killed.
- Weather
- visual conditions (good weather)
- Aircraft
- Kaman K-1200
- Registration
- N263KA · no longer on the register · serial A940033
- 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 helicopter experienced a total loss of engine power while hovering out of ground effect during a long-line logging operation. Witnesses observed the helicopter descend vertically with the rotors visibly slowing down, nose over to an inverted position, impact the ground inverted, and roll onto its left side. Initial examination of the engine revealed that when the power turbine was rotated, the engine output adapter attached to the reduction gearbox did not rotate, indicating a mechanical disconnect within the engine. Disassembly of the engine revealed severe damage to the sun gear shaft, which coupled the power turbine to the reduction gear box. Further disassembly and materials analysis disclosed an assembly error of one of the three aft planetary gear shaft roller bearings in the reduction gear box and improper crimping of the lockcup on the N1 seal and nut assembly. These two errors resulted in misalignment in the planetary gear train leading to high tooth loading in the sun gear shaft, which resulted in stripping and separation of gear teeth and loss of transmitted torque through the reduction gear box. Examination of maintenance records indicated that the bearing assembly error occurred during an overhaul of the reduction gear box by a certified repair station 822.8 operating hours before the accident. The improper crimping of the lockcup occurred during a repair by the same certified repair station performed 350.2 operating hours before the accident.
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: single-engine land; rotorcraft: helicopter
- Flight time: 4,019 hours in all; 1,646 in this make and model; 267 in the last 90 days
- Last flight review: September 1, 2004
- Medical certificate: Class 2 (with waivers/limitations)
- Seat: sngl
- Injury: fatal
The aircraft
- Airframe total time: 3,193 hours
- Last inspection: continuous airworthiness programme, March 1, 2006; 3 hours since
- Maximum gross weight: 6,000 lb
- Seats: 1
- Landing gear: fixed
- Engine: Honeywell T5317A-1 (turboshaft); 0 hours total
The flight
- Departed from: Dayville OR at 3:00 pm
- Flight plan: none
Weather at the time
- Light: daylight
- Visibility: 50 statute miles
- Sky: clear
- Temperature: 37°F (3°C), dew point 0°F (-18°C)
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.