# NTSB CHI94LA300: Bell 47 MARK-6, N19JM, Lake City, MN, August 26, 1994

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: August 26, 1994, 17:45 local (22:45 UTC)
- Place: Lake City, MN
- Coordinates: 44.439548, -92.27053 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=44.4395&lon=-92.2705&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report February 24, 1995
- Report: Approved by Office Director
- NTSB case key (mKey): 9656
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI94LA300
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/9656/pdf
- Page: https://openairdocs.org/ntsb/CHI94LA300

## Probable cause

THE LOSS OF LIFT RESULTING FROM THE PILOT'S FAILURE TO MAINTAIN ROTOR RPM DURING AN AERIAL APPLICATION TURN. THE POWER AVAILABLE FROM THE ENGINE WAS LESS THAN THAT REQUIRED TO REGAIN THE LOST ROTOR RPM.

## Sequence of events

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

- Loss of control - in flight, maneuvering - aerial application
  - rotor rpm - not maintained, pilot in command (cause)
  - level off - not possible, pilot in command (contributing factor)
- In flight collision with terrain/water, descent - uncontrolled
  - terrain condition - crop

## Analysis

WHILE PERFORMING A LOW LEVEL AGRICULTURAL APPLICATION TURN, THE PILOT REPORTED COMPLETING HIS TURN AND HAVING A LOWER THAN NORMAL ROTOR RPM.  THE TEMPERATURE WAS APPROXIMATELY 74 DEGREES FAHRENHEIT AND THE HUMIDITY WAS REPORTED BY THE PILOT AS HIGH. DENSITY ALTITUDE WAS APPROXIMATELY 2000 FEET.  ATTEMPTING TO REGAIN RPM AND LEVEL OFF WAS NOT SUCCESSFUL, AND THE HELICOPTER SPRAY BOOMS CONTACTED THE CORN CROP.  THE HELICOPTER STOPPED AND OVERTURNED.

## Factual narrative

On August 26, 1994, at 1745 hours central daylight time, a Bell BH-47 Mark-6 helicopter, N19JM, operated by Northland Helicopter, Inc., of Stacyville, Iowa, impacted in a crop field 4 miles south of Lake City, Minnesota, and was substantially damaged.  The commercially certificated pilot was uninjured and no fire occurred.  Visual meteorological conditions existed at the time of the accident and no flight plan was filed.  The flight operated under 14 CFR Part 137 as an agricultural application aircraft, and the flight had originated from a tending vehicle near the accident site at 1530 hours CDT.

The pilot reported that after making an application turn, rotor RPM decayed and he was unable to maintain level flight or regain the rotor rpm.  The temperature was 74 degrees Farenheit, the humidity was described by the pilot as high, the elevation was 1300 feet above mean sea level, and the density altitude was at least 2000 feet.  Post crash inspection of the helicopter and powerplant failed to reveal any discrepancies.

## Aircraft

- Registration: N19JM (not matched to a registry record)
- Reported make and model: BELL 47 MARK-6
- Category: Helicopter
- Serial number: 1921
- Airframe hours: 5852
- Engines: LYCOMING V0-435-A1F 260 horsepower reciprocating
- Damage: Substantial damage
- Flight: Aerial application, Part 137
- Operator: Northland Helicopter Inc
- Registered owner: Northland Helicopters, Inc
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: Annual, October 10, 1993, 170 hours before

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 46; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--no waivers/lim.; seat: front; flight hours: 5,796 total, 4,600 in this make and model, 5,766 as pilot in command

## Weather

- Conditions: Visual (VMC), Day
- Wind: 60° at 6 knots
- Visibility: 12 statute miles
- Lowest ceiling: 2,900 ft broken
- Temperature: 73 °F, dew point 70 °F
- Altimeter: 30.00 inHg
- Observed at: RST, 30 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 19940826034149A](https://openairdocs.org/incident/19940826034149A), Aug 26, 1994: Ccoptr TOMCATMK5A, Rochester, MN, Substantial damage. Lost lift settled into field.

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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