# NTSB DEN05TA072: Bell OH-58C, N198PD, Colorado Sprngs, CO, April 8, 2005

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Final report
- Date: April 7, 2005, 18:15 local (Apr 8, 2005, 00:15 UTC)
- Place: Colorado Sprngs, CO
- Coordinates: 38.83041, -104.80928 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=38.8304&lon=-104.8093&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 3 uninjured
- Status: Completed, report October 27, 2005
- Report: Approved by Office Director
- Parties: FAA Flight Standards Field Office
- NTSB case key (mKey): 61457
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN05TA072
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/61457/pdf
- Page: https://openairdocs.org/ntsb/DEN05TA072

## Probable cause

the failure of the N1 tachometer generator which resulted in a precautionary landing. Contributing factors include the frayed wire and the unsuitable terrain for a precautionary landing.

## Sequence of events

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

- Airframe/component/system failure/malfunction, cruise - normal
  - electrical system,electric wiring - frayed (contributing factor)
  - engine instruments,tachometer - failure (cause)
- Hard landing, descent - emergency
  - precautionary landing - performed, pilot in command
  - unsuitable terrain or takeoff/landing/taxi area - encountered (contributing factor)
  - terrain condition - uphill

## Analysis

According to the pilot, he was orbiting over a campus when the "engine out light illuminated in the cockpit," followed by an "audible engine out alarm" and the "N1 gauge dropped." The pilot elected to perform a precautionary landing to a field. The pilot stated that the terrain sloped uphill and the helicopter stopped "abruptly" and rock back and forth. A postaccident examination revealed that the N1 Tachometer Generator had failed. Further examination revealed that the N1 tachometer generator wire was not connected to the cannon plug and frayed. Examination of the helicopter's remaining systems revealed no anomalies.

## Factual narrative

On April 7, 2005, approximately 1815 mountain daylight time, a Bell OH-58C, N198PD, operated by the City of Colorado Springs Police Department, was substantially damaged during a forced landing 10 miles north of Colorado Springs, Colorado. Visual meteorological conditions prevailed at the time of the accident. The local public use flight was being operated under the provisions of Title 14 CFR Part 91 without a flight plan. The commercial certificated pilot and two passengers reported no injuries. The local flight originated approximately 1800.

According to the accident report submitted by the pilot, he was orbiting over a college campus when the "engine out light illuminated" in the cockpit. This light was followed by an "audible engine out alarm" and the "N1 gauge dropped." The pilot elected to perform a precautionary landing west of Interstate 25 on Air Force Academy property. The pilot stated that the terrain sloped uphill and the helicopter stopped "abruptly" and rock back and forth. Approximately 30 inches aft from the boom attach point, the boom buckled, leaving a wrinkle approximately 9 inches in length and approximately 2 inches at its deepest point.

A postaccident examination revealed that the N1 tachometer generator had failed. Further examination revealed that the N1 tachometer generator wire was not connected to the cannon plug and frayed. Examination of the helicopter's remaining systems revealed no anomalies.

## Aircraft

- Registration: [N198PD](https://openairdocs.org/aircraft/N198PD), registered now, S/N 68-16947 (OpenAirDocs)
- Reported make and model: Bell OH-58C
- Registry model: [Bell OH-58C](https://openairdocs.org/model/bell-oh-58c) (registry code 1181580) (OpenAirDocs)
- Category: Helicopter
- Serial number: 68-16947
- Airframe hours: 9433.3
- Engines: Rolls-Royce Allison 250 420 horsepower turbo shaft
- Damage: Substantial damage
- Flight: Public aircraft - local, Part 91
- Registered owner: City of Colorado Springs Police Department
- Airworthiness certificate: Standard, Normal
- Last inspection: Continuous airworthiness, April 1, 2005
- Departed: COS, Colorado Sprngs, CO

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 41; injuries: none; commercial; airplane ratings: single-engine land; medical: class 2, with waivers/limitations; last flight review May 1, 2004; seat: right; flight hours: 437 total, 350 in this make and model, 288 as pilot in command, 51 in the last 90 days, 14 in the last 30 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 30° at 18 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 54 °F, dew point 21 °F
- Altimeter: 30.29 inHg
- Observed at: KCOS, 10 nm away

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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