WPR22LA084 · Bell UH-1E
Marquis Aviation Bell UH-1E · Accident: system/component malfunction/failure (non-power) while maneuvering
From Los Banos Municipal Airport (LSN) to an unrecorded destination
Event
- NTSB case
- WPR22LA084
- 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
- Event fatalities
- Unknown
- 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-1E
- 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
- N333XL
- Operator
- Marquis Aviation
- Onboard fatalities
- Unknown
- Route
- From Los Banos Municipal Airport (LSN), Los Banos, CATo not recorded
- Aircraft age
- About 55 years (built 1967)
- 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 · low-altitude flying
- 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
- System/component malfunction/failure (non-power)
- 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 propeller/rotor
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The pilot was conducting aerial spray applications of a chemical to a field. He had checked the oil quantity of the 90° gearbox during the preflight check but did not recall the quantity of oil at the time. The pilot had operated the helicopter for about 45 minutes and, while making a turn, lost control of the helicopter. The helicopter descended and impacted terrain. Maintenance records revealed no anomalies. Postaccident examination of the 90° gearbox revealed severe damage to the internal components and no evidence of lubricating oil inside the housing. The pinion was severely deformed, which resulted in the loss of rotational drive to the tail rotor assembly and the subsequent loss of control. Examination of the oil level sight glass revealed that the inside was covered with a material that did not allow for sufficient viewing of the oil level. It is likely that, when the pilot looked at the oil level sight glass during his preflight check, he interpreted what he saw as an adequate amount of oil.
Probable cause
Failure of the 90° gearbox due to the lack of lubricating oil, which resulted in a loss of rotational drive to the tail rotor and a subsequent loss of control of the helicopter.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record WPR22LA084
- Event ID
- 20220127104563
- Case number
- WPR22LA084
- 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: investigation status, cause areas. 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: b39cb4ae3ad89c85c9b0f5e6ea43894ca4a2abb58ef0f6ad871f87e7c372dd29; retrieved 2026-09-16T14:55:00.328Z.