SEA00LA129 · Kaman K-1200
Kaman K-1200 · Accident: airframe, component or system failure while maneuvering
Event
- NTSB case
- SEA00LA129
- 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
- 0 · all aircraft and ground
- Ground fatalities
- 0
- 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
- N311KA
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From not recordedTo 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
- 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
- Airframe, component or system failure
- Also codedOther events the NTSB coded in the sequence, such as a wire strike after a loss of power. Flight Findings uses them for its kinds of event. Glossary
- Tree(s)
- 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
- Rotor drive system, engine to transmission drive › Fractured
- Rotor drive system, freewheeling sprag unit › Malfunction
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
While lifting approximately 5,000 pounds of logs from the drop area, the aero-logging helicopter experienced a malfunction of the free-wheeling sprag clutch assembly, and a resultant torsional separation of the engine drive adapter. Although the pilot attempted an emergency descent to a down-slope clearing, the aircraft impacted trees and dropped onto the terrain below.
Probable cause
The termination of power to the main rotor system as a result of the malfunction of the free-wheeling sprag clutch assembly, followed by the torsional overload separation of the engine adapter shaft. Factors include trees in the area where the emergency descent was attempted.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record SEA00LA129
- Event ID
- 20001212X21608
- Case number
- SEA00LA129
- 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. 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: 1c3c2d9ad79174adcd5e1cae1d11c2918d935946916d090760264f3eca9e54ab; retrieved 2026-09-21T10:34:33.629Z.