# NTSB FTW83FA232: Bell 47G, N739B, Zachary, LA, May 15, 1983

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Field investigation · Final report
- Date: May 15, 1983, 12:00 local (17:00 UTC)
- Place: Zachary, LA
- Location: 30.6644° N, 91.1658° W: Placed by OpenAirDocs: center of Zachary, LA, within about 6 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=30.6644&lon=-91.1658&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 1 serious, 1 minor
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 20723
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW83FA232
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/20723/pdf
- Page: https://openairdocs.org/ntsb/FTW83FA232

## Sequence of events

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

- Airframe/component/system failure/malfunction, landing - flare/touchdown
  - rotor drive system,tail rotor gearbox(90 deg) - fatigue (cause)
  - rotor drive system,tail rotor gearbox(90 deg) - separation (cause)
- Forced landing, landing - flare/touchdown
  - autorotation - performed, pilot in command(cfi)
- In flight collision with terrain/water, landing - flare/touchdown

## Analysis

THE TAIL ROTOR GEAR BOX SEPARATED FROM THE ACFT DURING PRACTICE AUTOROTATION. THE ACFT BEGAN TO SPIN RAPIDLY AND NOSE DOWN. INCREASING THE POWER BROUGHT THE NOSE UP BUT INCREASED THE SPEED OF ROTATION. THE ACFT HIT ON ONE SKID STILL IN A RAPID SPIN. THE OCCUPANTS WERE ABLE TO EXIT THE WRECKAGE AND CRAWL AWAY. THE TAILROTOR GEAR BOX WAS FOUND 100 YDS AWAY. AN EXAM REVEALED THAT THE GEARBOX STUDS HAD FAILED FROM FATIGUE.

## Aircraft

- Registration: N739B (not matched to a registry record)
- Reported make and model: BELL 47G
- Category: Helicopter
- Engines: FRANKLIN 6V4 240 horsepower reciprocating
- Damage: Substantial damage
- Flight: Instructional, Part 91
- Operator: James T Lewis
- Departed: BAKER, LA

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 56; flight instructor, airline transport; airplane ratings: multi-engine land, single-engine sea, single-engine land; instrument ratings: airplane; medical: class 1, unknown; flight hours: 23,210 total, 1,550 in this make and model, 210 in the last 90 days, 5 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 170° at 12 knots
- Visibility: 7 statute miles
- Lowest ceiling: 5,000 ft broken
- Temperature: -0 °F, dew point -0 °F
- Observed at: BTR

## 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 19830515019409A](https://openairdocs.org/incident/19830515019409A), May 15, 1983: Bell H13B, Zachary, LA, Destroyed. Tail rotor gear box separated from helicopter. Fatigue failure of the studs that attach tail rotor caused crash.

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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