WPR10LA117 · Bell 47G-4A
Inland Crop Dusters Bell 47G-4A · Accident: hard landing
From Shafter Airport - Minter Field (MIT) to Shafter Airport - Minter Field (MIT)
Event
- NTSB case
- WPR10LA117
- 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 47G-4A
- Aircraft type
- Bell 47
- 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
- N28938
- Operator
- Inland Crop Dusters
- Onboard fatalities
- Unknown
- Route
- From Shafter Airport - Minter Field (MIT), Shafter, CATo Shafter Airport - Minter Field (MIT), Shafter, 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
- Landing · flare/touchdown
- 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
- Hard landing
- 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 systems
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The pilot reported that he was maneuvering the helicopter to make an aerial application pass. At approximately 80 feet above ground level, he heard a muffled "crack/bang" and the helicopter immediately yawed and he experienced lateral vibrations in the cyclic. The pilot then initiated a forced landing with the shaking becoming more violent. The helicopter subsequently landed hard with the engine still running. The main rotor blades contacted and severed the tail boom, and the engine separated from its mounts. Postaccident examination of the helicopter revealed that a main rotor counterweight was missing. Examination of the broken counterweight rod end showed evidence of corrosion over approximately 45 percent of the diameter of the rod end. Maintenance records indicate that a Service Bulletin to inspect main rotor counterweight rods for pit corrosion had not been complied with. The Service Bulletin states that after an initial inspection of the main rotor counterweight rods, recurrent inspections should be accomplished every 300 hours of time in service.
Probable cause
The loss of a main rotor blade counterweight due to corrosion. Contributing to the accident was the failure of the operator to perform the initial and recurrent inspections required by a Service Bulletin to detect the corrosion in the counterweight.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record WPR10LA117
- Event ID
- 20100125X12744
- Case number
- WPR10LA117
- 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. 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: dcc25e8a65dfc48d29c2462446ad4baea77307dd30c0a23ae9a063bf53b9eaba; retrieved 2026-09-15T13:38:41.124Z.