LAX04LA015 · Bell UH-1B
Bell UH-1B · Accident: total loss of engine power (mechanical failure) while maneuvering
From Durham, CA to an unrecorded destination
Event
- NTSB case
- LAX04LA015
- 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
- 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
Bell UH-1B
- 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
- N234SJ
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Durham, CATo 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 91: General Aviation
- 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
- 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
- Total loss of engine power (mechanical failure)
- 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
- Turbine assembly, shaft › Overload
- Turbine assembly, shaft › Separation
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 landed hard and rolled over during an autorotation following a loss of engine power. The pilot was demonstrating crop dusting turns and maneuvers for school children. He had completed several simulated passes over a field. He returned to the middle of a field, and turned into a light wind in preparation for landing. The helicopter lost power and entered an unexpectedly rapid descent. He was unable to prevent a hard landing and rollover. The teardown and examination of the engine disclosed that the power turbine shaft retaining bolt had failed in overload, allowing the shaft to float in a fore and aft manner and eventually damaging the blades on the power turbine disk. The type and degree of damage to the turbine section shafting and related components was indicative of the separation of the bolt at some undetermined point in time prior to the accident flight.
Probable cause
Separation of the power turbine shaft retaining bolt resulting in extensive power turbine area damage and a loss of shaft output power.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record LAX04LA015
- Event ID
- 20031022X01797
- Case number
- LAX04LA015
- 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: 51ae2046fc0da8077dcf5f848de8e4168d67815023c222d48fae1ba83bcf1e19; retrieved 2026-09-22T08:19:56.438Z.