SEA86FA137 · Bell UH-1L
Bell UH-1L · Accident: airframe, component or system failure while maneuvering
Event
- NTSB case
- SEA86FA137
- 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
- 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
Bell UH-1L
- Aircraft type
- Bell UH-1
- 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
- N4964N
- 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
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Destroyed
Cause areas
- Rotor drive system, intermediate gearbox(42 deg) › Fatigue
- Terrain condition › None suitable
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
N4964N, A BELL UH-1L, WAS BEING OPERATED IN LOGGING OPS BY AN EXPERIENCED, MILITARY TRAINED PLT WHO POSSESSED 6000 HRS OF FLT EXPERIENCE IN MODEL. WHILE LIFTING A SLING LOAD GND CREW RPTD SMOKE FROM THE TAIL ROTOR AREA. PLT RELEASED SLING LOAD & ACKNOWLEDGED THE WARNING RADIOING HIS INTENTIONS TO LAND NEARBY. THE SUBSEQUENT LOSS OF TAIL ROTOR/DIRECTNL CNTRL PLACED ROTORCRAFT IN A CONDITION WHEREBY AN AUTOROTATION WAS NOT POSSBL & A RUN ON LNDG WAS NECESSARY. UNSUITABLE TERRAIN LEFT THE PLT WITH ONLY TWO FORCED LNDG OPTIONS, ONE ON CURVING, HILLY HWY WITH POTENTIAL FOR A COLLISION WITH AUTO TRAFFIC, OR THE OTHER INTO HEAVILY TREED TERRAIN. THE PLT APPEARS TO HAVE CHOSEN THE LATTER. IT IS NOT APPARENT WHY HE CHOSE THIS OPTION RATHER THAN DIVERTING TO A NEARBY AIRSTRIP OR SOME OTHER LEVEL FORCED LNDG AREA. THE 42 DEGREE GEARBOX, WHICH HAD BEEN OVERHAULED AND INSTALLED 195 HRS PREVIOUSLY IN ACFT, WAS FOUND TO HAVE FAILED WHEN THE INPUT PINION GEAR FRACTURED IN FATIGUE ORIGINATING FROM CORROSION.
Verbatim NTSB analysis from the NTSB dataset
Sources
NTSB record SEA86FA137
- Event ID
- 20001213X33699
- Case number
- SEA86FA137
- 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: 7327372450ed2f3aa76cf579630d6c251362a2af8dda5bd0c5e11bc3c002f450; retrieved 2026-09-21T04:33:00.050Z.