NTSB Factual Report

On May 13, 2004, about 0735 eastern daylight time, a Garlick Helicopters Inc. OH-58A, N59MH, was substantially damaged during a forced landing, following a partial loss of engine power in cruise flight near Columbia, Maine. The certificated commercial pilot was not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the local aerial application flight conducted under 14 CFR Part 137.

The pilot reported that prior to the accident, he had been flying uneventfully for approximately 2 hours. The helicopter landed in a private field, where additional chemical spray and fuel was loaded. The pilot then departed the private field, and was flying toward another field to spray blueberries. About 1 minute after takeoff, at 200 feet agl, the engine lost partial power. The pilot attempted to perform a run-on landing to a field; however, the helicopter impacted trees prior to the field. During the impact, the fuselage and tailboom sustained substantial damage.

Following the accident, a test run of the engine was performed at the manufacturer's facility, under the supervision of a Federal Aviation Administration (FAA) inspector. The test run was conducted with the original fuel control unit, power turbine governor, and engine fuel pump. The only slave component used was a burner drain valve, which was replaced due to the accident valve being stuck in the open position, consistent with impact damage. The inspector stated that the engine ran continuously at 95 percent power, with no interruptions or discrepancies noted.

A fuel sample from the accident helicopter was tested at the engine manufacturer's facility on July 21, 2004. The test revealed 800 parts per million (ppm) of water present. However, the fuel sample was recovered from the helicopter 6 days after the accident, and remained in a sealed container until the test. A fuel sample was taken from the fueling truck on the day of the accident, and tested on February 28, 2005. Testing of that fuel sample revealed 4 ppm of water present. The operator reported that the same fuel truck was used before and after the accident, with no problems noted.

According to data provided by a representative from the engine manufacturer, their maximum acceptable level of free and dissolved water was 260 ppm. The data also revealed that the Aviation Fuel Quality Control Handbook listed the maximum acceptable level as 60 ppm. In addition, the United States MIL-STD-1518B listed the maximum acceptable level as 10 ppm.

The pilot reported a total flight experience of approximately 11,369 hours; of which, all of his experience was in helicopters, and 2,500 hours were in the same make and model as the accident helicopter.

NTSB Probable Cause

A partial loss of engine power for undetermined reasons, which resulted in a forced landing during cruise flight.