WPR18LA004 · Western International Avia Inc UH 1H
Western International Avia Inc UH 1H · Accident: flight control system malfunction/failure during landing
From Arbuckle, CA to Arbuckle, CA
Event
- NTSB case
- WPR18LA004
- 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
Western International Avia Inc UH 1H
- Aircraft type
- Western International Avia 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
- N247PV
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Arbuckle, CATo Arbuckle, CA
- Aircraft age
- About 52 years (built 1965)
- 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
- Landing
- 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
- Flight control system malfunction/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
- Aircraft › Aircraft propeller/rotor
- Not determined › Not determined
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 and mechanic reported that, before the accident, the mechanic had adjusted the helicopter’s main rotor track and balance. After the mechanic made the final adjustments, the pilot hovered the helicopter to a wash rack for cleaning. Subsequently, while the pilot was repositioning the helicopter to a nearby landing cart and just as the front portions of the skids were over the cart, the collective began to oscillate, followed by the skids striking the cart. The pilot attempted to land the helicopter as it continued to oscillate, but the right skid slid off the cart. The helicopter then rolled onto its right side and impacted the ground. The mechanic reported that all components prior to the accident were in good working order and that the track and balance adjustments had resulted in satisfactory monitoring equipment readings prior to the accident. Examination of the helicopter did not reveal evidence of any preaccident malfunctions or failures that would have precluded normal operation. The reason for the oscillations could not be determined based on the available information.
Probable cause
A collective control malfunction for reasons that could not be determined.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record WPR18LA004
- Event ID
- 20171007X12417
- Case number
- WPR18LA004
- 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, 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: c179cd8ae7a23dcb17c2914c46aaaf088c6def6a27178d733eae3d34ff45a4c8; retrieved 2026-09-16T05:55:11.047Z.