# NTSB FTW87LA195: Bell 206L-1, N2764F, New Iberia, LA, August 12, 1987

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: August 12, 1987, 09:00 local (14:00 UTC)
- Place: New Iberia, LA
- Coordinates: 30.000595, -91.810501 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=30.0006&lon=-91.8105&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report May 2, 1988
- Report: Approved by Office Director
- NTSB case key (mKey): 22417
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW87LA195
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/22417/pdf
- Page: https://openairdocs.org/ntsb/FTW87LA195

## 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
  - misc rotorcraft,tail boom - failure,total (cause)
  - autorotation - performed, dual student (cause)
  - misc rotorcraft,tail boom - vibration (cause)
  - run on landing - performed, dual student (cause)
  - terrain condition - soft (contributing factor)
  - airspeed - misjudged, dual student (cause)
  - supervision - inadequate, pilot in command(cfi) (cause)

## Analysis

CREW PERFORMING PRACTICE TOUCHDOWN AUTOROTATIONS DURING A TRNG FLT. ON 4TH AUTOROTATION, ACFT TOUCHED DOWN WITH EXCESS GRND SPEED AND SKIDDED FOR APPROX 75' ON THE WET, SOFT GRASS. WHEN CREW APPLIED POWER BACK TO FLIGHT RPM THEY HEARD A GRINDING SOUND AND FELT A VIBRATION. VISUAL INSP REVEALED THAT THE TAILBOOM HAD SEPARATED AFT OF THE ATTACHMENTS DUE TO RESONANCE. THIS ACFT IS SUBJECT TO RESONANCE IF ROTOR RPM IS ALLOWED TO DECAY BELOW 70% DURING TOUCHDOWN AUTOROTATIONS OR DURING LENGTHY GROUND RUNS.

## Aircraft

- Registration: [N2764F](https://openairdocs.org/deregistered/N2764F-2006-07-18), registration cancelled 2006-07-18, S/N 45279, built 1979 (OpenAirDocs)
- Reported make and model: BELL 206L-1
- Registry model: [Bell Helicopter Textron 206L-1](https://openairdocs.org/model/bell-helicopter-textron-206l-1) (registry code 1182107) (OpenAirDocs)
- Registry engine: [Allison 250-C28 series](https://openairdocs.org/engine/allison-250-c28-series) (registry code 03022, turbo-shaft) (OpenAirDocs)
- Category: Helicopter
- Serial number: 45279
- Airframe hours: 6752
- Engines: ALLISON 250-C28 435 horsepower turbo shaft
- Damage: Substantial damage
- Flight: Instructional, Part 91
- Operator: Petroleum Helicopters,Inc.
- Registered owner: Petroleum Helicopters, Inc
- Airworthiness certificate: Standard, Normal
- Last inspection: AAIP, July 28, 1987, 35 hours before
- Departed: LFT, LAFAYETTE, LA
- Flight plan: Company VFR
- Airport: ARA, Acadiana Reg., runway 16, 5,000 × 200 ft, grass/turf

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 39; commercial, flight instructor; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane, helicopter; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 6,250 total, 3,227 in this make and model, 5,965 as pilot in command, 38 in the last 90 days, 4 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 220° at 7 knots
- Visibility: 7 statute miles
- Lowest ceiling: 2,000 ft overcast
- Temperature: 88 °F
- Altimeter: 29.00 inHg
- Observed at: ARA

## 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 19870812046019A](https://openairdocs.org/incident/19870812046019A), Aug 12, 1987: Bell 206L1, New Iberia, LA, Substantial damage. The tailboom fell off during practice autorotations. Suspect pilot let rotor speed fall into resonance range.

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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