WPR24LA041 · Bell OH-58A
Bell OH-58A · Accident: loss of engine power (total) during initial climb
Event
- NTSB case
- WPR24LA041
- 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 OH-58A
- Aircraft type
- Bell 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
- N158TR
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From not recordedTo not recorded
- Aircraft age
- About 52 years (built 1971)
- 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
- Initial climb
- Defining eventThe 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 (total)
- 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
- Aircraft › Aircraft power plant
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
The pilot was conducting agricultural operations at night and had just departed from a company loading area. About 150 ft above ground level (agl), the pilot experienced a sudden power surge, abnormal engine noise, and vibration. The pilot believed that engine failure was imminent and turned back toward his point of departure. Engine power decayed, and the pilot bled off rotor rpm to maneuver over terrain toward flat ground. The helicopter landed hard, entered a pylon whirl condition, and the main rotor hub assembly separated from the main rotor mast. Postaccident examination of the airframe revealed no evidence of preaccident mechanical malfunction or failure. However, postaccident examination revealed a sheen of oil beneath the engine and that the engine’s compressor (N1) and power turbine (N2) systems were seized. Further examination of the engine revealed multiple failed bearings, failed drives, and fractures within the turbine scavenge oil pump assembly. The engine had been installed on the helicopter about 10 flight hours before the accident. Based on metallurgical analysis of the engine components, the No. 8 bearing likely failed and shed debris to the oil pump, which bound the first level oil pump gears and led a gear tooth to fracture and the pump driveshaft to fail. Subsequently, the engine was starved of oil and lost all power. The cause of the bearing failure could not be determined.
Probable cause
A total loss of engine power due to the failure of the No. 8 bearing and the subsequent failure of the scavenge oil pump.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record WPR24LA041
- Event ID
- 20231127193429
- Case number
- WPR24LA041
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
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: local date, investigation status, coordinates, cause areas. Values present in the bulk record are kept.
- The date is the local date; the NTSB stores the UTC date 2023-11-21.
- API snapshot SHA-256: 90f27b0732bd8691725ecb60eef48b3eae247aba01a6340f95ac1c1fc88e7171; retrieved 2026-09-16T18:19:15.531Z.