# NTSB DEN84FA207: Bell 206B, N3173L, Englewood, CO, July 2, 1984

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Field investigation · Final report
- Date: July 2, 1984, 17:14 local (23:14 UTC)
- Place: Englewood, CO
- Coordinates: 39.610183, -104.879997 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=39.6102&lon=-104.8800&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 2 fatal
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 16226
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN84FA207
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/16226/pdf
- Page: https://openairdocs.org/ntsb/DEN84FA207

## Sequence of events

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

- Airframe/component/system failure/malfunction, approach - vfr pattern - final approach
  - rotorcraft flight control,cyclic control - disconnected (cause)
  - maintenance,installation - improper, company maintenance personnel (cause)
  - checklist - inadequate, manufacturer (contributing factor)
  - aircraft preflight - inadequate, pilot in command (contributing factor)
- Loss of control - in flight, approach - vfr pattern - final approach
  - directional control - not possible, pilot in command
- In flight collision with terrain/water, descent - uncontrolled

## Analysis

WITNESSES STATED THE HELICOPTER ENTERED A 'HARD LEFT TURN' INTO A NEAR INVERTED POSITION BEFORE 'IT WENT DOWN HARD AND FAST.' INSPECTION DISCLOSED THE METAL CONNECTION FOR THE LEFT CYCLIC STICK WAS BROKEN IN HALF. (PLT WAS FLYING FROM LEFT SEAT.) EXAM OF THE CYCLIC STICK QUICK DISCONNECT LOCKING NUT REVEALED IT WAS HELD IN PLACE ON THE CONNECTOR BY 1 THREAD. PROPERLY INSTALLED, THE LOCKING NUT TIGHTENS DOWN OVER 6 THREADS ON THE CONNECTOR. WHEN BACKED OUT TO 1 THREAD, MOVEMENT OF THE CYCLIC WILL NOT NOT PRODUCE A CORRESPONDING CHANGE IN THE LATERAL CONTROL HYDRAULIC SERVOS. THE CYCLIC WAS LAST REMOVED APRX 80 HRS PRIOR TO THE ACCIDENT DURING MAINTENANCE. ON 7/17/84, BELL ISSUED OPERATIONS SAFETY NOTICE WHICH IN PART READ, 'FLIGHT CREWS ARE CAUTIONED TO ASSURE QUICK REMOVAL FLIGHT CONTROLS ARE PROPERLY INSTALLED PRIOR TO OPERATING THE HELICOPTER.' PRIOR TO THIS NOTICE, NO REQUIREMENTS EXISTED TO DO SO.

## Aircraft

- Registration: [N3173L](https://openairdocs.org/deregistered/N3173L-1990-02-14), registration cancelled 1990-02-14, S/N 3677 (OpenAirDocs)
- Reported make and model: BELL 206B
- Registry model: [Bell 206B](https://openairdocs.org/model/bell-206b) (registry code 1181511) (OpenAirDocs)
- Category: Helicopter
- Serial number: 3677
- Airframe hours: 2770
- Engines: ALLISON 250-C20J 317 horsepower turbo shaft
- Damage: Destroyed
- Flight: Personal, Part 91
- Registered owner: Ferris F. Hamilton
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, September 20, 1983, 805 hours before
- Departed: ENGLEWOOD, CO
- Airport: APA, Arapahoe County

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 39; airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: left; toxicology performed; flight hours: 5,000 total, 101 in the last 90 days

## Weather

- Conditions: Visual (VMC), Day
- Wind: 90° at 12 knots
- Visibility: 40 statute miles
- Lowest ceiling: none
- Temperature: 84 °F, dew point 46 °F
- Altimeter: 30.00 inHg
- Observed at: APA, 1 nm away

## 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 19840702032049A](https://openairdocs.org/incident/19840702032049A), Jul 2, 1984: Bell 206B, Arapahoe, CO, Destroyed. Aircraft made turn until almost upside down and crashed. Pilot in left seat. Cyclic control stick installed wrong.

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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