SEA06FA067 · Kaman K-1200
Kaman K-1200 · Accident: loss of engine power while maneuvering
From Dayville, OR to an unrecorded destination
Event
- NTSB case
- SEA06FA067
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 1 · all aircraft and ground
- Ground fatalities
- Unknown
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Kaman K-1200
- Aircraft type
- Kaman K-1200
- Category
- Helicopter
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N263KA
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Dayville, ORTo not recorded
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 133: Rotorcraft Ext. Load
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- Maneuvering · hover out of ground effect
- First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Loss of engine power
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Other maintenance personnel › Maintenance, installation, improper
- Other maintenance personnel › Maintenance, overhaul, improper
- Turboshaft engine, gas generator turbine shaft › Loose part/bolt/nut/clamp/etc
- Turboshaft engine, reduction gear box › Failure, total
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
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.
Probable cause
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.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record SEA06FA067
- Event ID
- 20060327X00354
- Case number
- SEA06FA067
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status, coordinates. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 71944a0c09632c9409e3afa06594a69fd7b8d9555e0e0b4e8c59360a5f68c190; retrieved 2026-09-20T17:29:48.325Z.