# NTSB MKC85FA189: Bell 47G-2A, N3951U, Sedalia, MO, August 17, 1985

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Field investigation · Final report
- Date: August 17, 1985, 16:40 local (21:40 UTC)
- Place: Sedalia, MO
- Coordinates: 38.700626, -93.229881 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=38.7006&lon=-93.2299&mi=10
- Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 1 serious, 2 uninjured
- Status: Completed
- Report: Approved by Office Director
- ADs cited in the narratives: [AD 81-04-03](https://openairdocs.org/ad/81-04-03) (OpenAirDocs)
- NTSB case key (mKey): 33852
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MKC85FA189
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/33852/pdf
- Page: https://openairdocs.org/ntsb/MKC85FA189

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Airframe/component/system failure/malfunction, takeoff
  - rotor drive system,tail rotor drive shaft bearing - failure,total (cause)
  - rotor drive system,tail rotor drive shaft - overload
- Forced landing, takeoff
- In flight collision with object, landing
  - object - vehicle (contributing factor)

## Analysis

THE PLT WAS TAKING 2 PASSENGERS ON A HELICOPTER RIDE AT A FAIR. IMMEDIATELY AFTER LIFT-OFF, HE ENCOUNTERED A SITUATION WHERE HE WAS UNABLE TO MAINTAIN DIRECTIONAL CONTROL, SO HE REDUCED POWER & LANDED. BEFORE COMING TO REST, THE TAIL OF THE HELICOPTER STRUCK A VAN. AN INVESTIGATION REVEALED THAT THE INNER BEARING (PN 47-620-605-001) OF THE TAIL ROTOR DRIVE HAD FAILED, THEN THE DRIVE SHAFT FAILED. AD 81-04-03, AMENDMENT 39-4029 BECAME EFFECTIVE ON 2/2/81 TO REPLACE THE BEARING IN THE NEXT 600 HRS OF SERVICE. HOWEVER, THE HELICOPTER HAD ACCUMULATED LESS THAN 600 HRS SINCE THAT DATE.

## Aircraft

- Registration: [N3951U](https://openairdocs.org/aircraft/N3951U), registered now, S/N 1376 (OpenAirDocs)
- Reported make and model: BELL 47G-2A
- Registry model: [Bell 47G-2A](https://openairdocs.org/model/bell-47g-2a) (registry code 1181012) (OpenAirDocs)
- Category: Helicopter
- Serial number: 1376
- Airframe hours: 12302
- Engines: LYCOMING V0-435-A1B 200 horsepower reciprocating
- Damage: Substantial damage
- Flight: Other work use, Part 91
- Registered owner: Metropolitan Helicopter, Inc.
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, June 22, 1985, 209 hours before

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 30; airline transport, flight instructor; airplane ratings: single-engine sea, single-engine land, multi-engine land; instrument ratings: airplane, helicopter; medical: class 1, valid medical--no waivers/lim.; seat: front; flight hours: 6,684 total, 1,200 in this make and model, 6,494 as pilot in command, 151 in the last 90 days, 6 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 230° at 7 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 88 °F
- Altimeter: 29.00 inHg
- Observed at: COU

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 19850817039249A](https://openairdocs.org/incident/19850817039249A), Aug 17, 1985: Bell 47G2A, Sedalia, MO, Substantial damage. Lost directional control after takeoff. During autorotation tail struck a van. Rotor transmission bearing failed.

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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