CHI95LA003 · Bell 47G2
Bell 47G2 · Accident: airframe, component or system failure en route
From Decatur Airport (DEC) to an unrecorded destination
Event
- NTSB case
- CHI95LA003
- 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
- 0
- 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 47G2
- 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
- N5193B
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Decatur Airport (DEC), ILTo not recorded
- 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 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
- En route · climb to cruise
- 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
- Airframe, component or system 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
- Rotor drive system, freewheeling sprag unit › Disengaged
- Rotor drive system, freewheeling sprag unit › Failure
Approximate · Estimated position: the centre of Decatur, IL, the place the record names. Not the accident site.
NTSB narrative
THE PILOT STATED THAT AFTER COMPLETING A LINE PATROL, HE MADE A CLIMBING LEFT TURN TO RETURN TO THE AIRPORT. AT APPROXIMATELY 50 TO 75 FEET ABOVE THE GROUND, THE PILOT HEARD A STRANGE SOUND, THE ENGINE BEGAN TO OVERSPEED, AND THE HELICOPTER BEGAN TO DESCEND. HE LOWERED THE COLLECTIVE AND PLACED THE HELICOPTER INTO AN AUTOROTATION TO MAKE A FORCED LANDING ON A ROAD. THE HELICOPTER TOUCHED DOWN HARD AND WAS DAMAGED. A POSTACCIDENT INVESTIGATION REVEALED 13 OF 32 ROLLER SPRINGS INSIDE THE FREEWHEELING UNIT OF THE TRANSMISSION WERE BROKEN CAUSING THE UNIT TO BECOME DISENGAGED.
Probable cause
the failure of the roller springs in the freewheeling unit of the transmission which caused the unit to disengage.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CHI95LA003
- Event ID
- 20001206X02399
- Case number
- CHI95LA003
- 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. 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: 68d52580fbb785ab28c19e13642e2aa17416943393d0973148173c3a544e13b3; retrieved 2026-09-21T22:28:31.878Z.