LAX05FA264 · San Joaquin Helicopters OH-58A+
San Joaquin Helicopters OH-58A+ · Accident: total loss of engine power (mechanical failure) while maneuvering
From Lancaster, CA to Lancaster, CA
Event
- NTSB case
- LAX05FA264
- 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
San Joaquin Helicopters OH-58A+
- Aircraft type
- San Joaquin OH-58
- 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
- N177SJ
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Lancaster, CATo Lancaster, CA
- 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 137: Agricultural
- 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 · aerial application
- 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
- Miscellaneous, engine › Fatigue
- Other maintenance personnel › Maintenance, alignment, incorrect
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
Following a loss of engine power, the helicopter impacted the ground during the application of chemicals to an agricultural field. Post accident examination of the engine showed that the power turbine to pinion gear coupling had fractured. Metallurgical examination of the affected components showed that the coupling failed in fatigue, which effectively separated the engine from the main rotor gearbox. The fatigue was the result of a misaligned power turbine outer shaft, where the axis of the turbine shaft was angled slightly relative to the coupling and pinion axes. The turbine section had been removed from another engine due to metal contamination. The turbine section was repaired and subsequently installed on the accident helicopter on August 11, 2004, where it operated for 770.3 hours prior to the accident. Weight and balance calculations showed that the helicopter was in excess of its certificated maximum gross weight by 174 pounds.
Probable cause
The pinion to turbine shaft coupling failed in fatigue due to a misaligned turbine shaft, which resulted in a loss of engine power.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record LAX05FA264
- Event ID
- 20050817X01264
- Case number
- LAX05FA264
- 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: ecc593345d64a41982be4066f41079c6bcddef23c58a0ac82ba83de06bd057c3; retrieved 2026-09-20T17:56:16.480Z.