# NTSB DEN90LA180: Bell 47G-3B1, N73957, Canon City, CO, September 2, 1990

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Limited investigation · Final report
- Date: September 2, 1990, 12:35 local (18:35 UTC)
- Place: Canon City, CO
- Coordinates: 38.440189, -105.230621 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=38.4402&lon=-105.2306&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: Minor injuries
- Injuries: 1 minor
- Status: Completed, report December 14, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 17986
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN90LA180
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/17986/pdf
- Page: https://openairdocs.org/ntsb/DEN90LA180

## Probable cause

THE PILOT'S FAILURE TO MAINTAIN AN ADEQUATE PATTERN ALTITUDE AND THE POSSIBLE EXISTENCE OF ADVERSE WINDS DUE TO THE SURROUNDING TERRAIN.

## Sequence of events

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

- In flight collision with object, approach - vfr pattern - downwind
  - terrain condition - mountainous/hilly (contributing factor)
  - terrain condition - high obstruction(s) (contributing factor)
  - weather condition (cause)
  - altitude - inadequate, pilot in command (cause)

## Analysis

THE HELICOPTER COLLIDED WITH POWER LINES WHILE ON A DOWNWIND TO THE HELIPAD. ACCORDING TO WITNESSES, THE HELICOPTER WAS TRAVELLING PERPENDICULAR TO AN ELECTRICAL TRANSMISSION LINE AT ABOUT 60 KNOTS WHEN IT COLLIDED WITH THE TOP OF A TWO WIRE SET AT ABOUT 30 FEET AGL. PAINT TRANSFER FROM THE T/R SKID WAS FOUND ON THE DAMAGED POWER LINE. AFTER STRIKING THE WIRE THE T/R SEPARATED AT THE GEAR BOX MOUNTING FLANGE; SMALL PIECES OF THE T/R BLADE WERE FOUND ON THE GROUND BELOW THE POINT OF INITIAL WIRE CONTACT. THE PILOT STATED THAT DURING THE DOWNWIND CLIMBING TURN AFTER TAKEOFF, AND WHILE PASSING OVER A GULLY NEAR A 6,200-FT RIDGE, HE HAD AN ENCOUNTER WITH WINDSHEAR AT 230 FEET AGL WHICH RESULTED IN LOSS OF 200 FEET AND THE SUBSEQUENT COLLISION. THE EXISTENCE OF THE REPORTED 'WINDSHEAR', OR POSSIBLE DOWNDRAFT COULD NOT BE VERIFIED.

## Aircraft

- Registration: N73957 (not matched to a registry record)
- Reported make and model: BELL 47G-3B1
- Category: Helicopter
- Serial number: 2827
- Engines: ALLISON 250C20B turbo shaft
- Damage: Substantial damage
- Flight: Personal, Part 91
- Registered owner: Tracie Crocker
- Airport: NONE, Brown'S Fort Helipad

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 28; commercial; instrument ratings: helicopter; medical: class 2, valid medical--no waivers/lim.; toxicology performed; flight hours: 1,800 total, 180 in this make and model, 1,550 as pilot in command, 322 in the last 90 days, 160 in the last 30 days, 6 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 60° at 10 knots, gusting 6
- Visibility: 15 statute miles
- Lowest ceiling: none
- Temperature: 86 °F, dew point 55 °F
- Observed at: PUB, 44 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 19900902038109A](https://openairdocs.org/incident/19900902038109A), Sep 2, 1990: Bell 47G3B1, Canon City, CO, Substantial damage. Downdraft on downwind to helipad. Struck powerline. Separated tail rotor. Blamed downdraft. Unverified. Too low.

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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