CHI95LA093 · Bell 206L
Bell 206L · Accident: airframe, component or system failure during initial climb
From Rolla Downtown Airport (RLA) to Jefferson City Memorial Airport (JEF)
Event
- NTSB case
- CHI95LA093
- 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 206L
- Aircraft type
- Bell 206
- 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
- N970CC
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Rolla Downtown Airport (RLA)To Jefferson City Memorial Airport (JEF), JEFFERSON, MO
- 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
- Initial climb
- 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
- Miscellaneous, bolt/nut/fastener/clamp/spring › Fatigue
- Rotor drive system, engine to transmission drive › Disconnected
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
THE PILOT OF A TURBINE POWERED HELICOPTER SAID HE BEGAN A HOVER ABOUT THREE FEET ABOVE THE GROUND, TURNED THE HELICOPTER INTO THE WIND, AND INITIATED A TAKEOFF. ACCORDING TO WITNESSES, THE HELICOPTER HAD STARTED TO MOVE FORWARD AND HAD ATTAINED AN ALTITUDE OF ABOUT 25 FEET, WHEN THEY HEARD A CHANGE IN THE SOUND OF THE ENGINE. THE PILOT STATED 'AS POWER WAS BROUGHT IN, A LOUD METALLIC TYPE POP WAS HEARD.' HE SAID THE HELICOPTER YAWED LEFT AFTER THE 'POP' WAS HEARD, AND THAT IT DID NOT RESPOND TO CONTROL INPUTS. THE HELICOPTER FLEW OVER AN EMBANKMENT, AND ITS ROTOR BLADES STRUCK THE SIDE OF THE EMBANKMENT. AFTER THE BLADE STRIKE, THE HELICOPTER ROLLED OVER ONTO ITS LEFT SIDE, THEN ON ITS RIGHT SIDE AND CAME TO REST. EXAMINATION OF THE HELICOPTER AND ITS COMPONENTS REVEALED THE ATTACHMENT BOLTS THAT CONNECTED THE DRIVESHAFT TO THE GEARED PORTION OF THE DRIVESHAFT COUPLING HAD FAILED. METALLURGICAL EXAMINATION REVEALED THAT TWO OF THE BOLTS HAD FAILED FROM FATIGUE, THE OTHER TWO BOLTS HAD EVIDENCE OF OVERLOAD FAILURE. ALSO, AFTER DISASSEMBLY, A TENSION (CENTERING) SPRING WAS DISCOVERED TO BE MISSING FROM THE TRANSMISSION END OF THE DRIVESHAFT (WHICH WOULD HAVE ALLOWED THE BOLT HEADS TO CONTACT THE GREASE RETAINING PLATE). THE LAST ANNUAL INSPECTION OF THE HELICOPTER AND ENGINE WAS ON 11/3/93.
Probable cause
FATIGUE FAILURE OF TWO ATTACHMENT BOLTS THAT CONNECTED THE DRIVESHAFT TO THE GEARED PORTION OF A DRIVESHAFT COUPLING. FACTORS RELATING TO THE ACCIDENT WERE: INADEQUATE MAINTENANCE, UNEVEN TERRAIN IN THE TOUCHDOWN AREA FOR THE FORCED LANDING, AND THE UNFAVORABLE HEIGHT/VELOCITY SITUATION OF THE HELICOPTER WHEN THE DRIVESHAFT DISCONNECT OCCURRED.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CHI95LA093
- Event ID
- 20001207X02945
- Case number
- CHI95LA093
- 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: 5992c0744c548d94d984fef835d53b8d2cd7e60b1bb6cb05db66440e020c018a; retrieved 2026-09-23T00:12:23.819Z.