NTSB Factual Report

On June 10, 1993, at 1900 central daylight time, a Bell 47G-2A-1 helicopter, N73988, was destroyed, and the commercial pilot sustained fatal injuries, in an accident in Phlox, Wisconsin. During maneuvering of this aerial application flight, the pilot lost control and the helicopter impacted the ground. There was no flight plan filed for this 14 CFR Part 91 flight operating in visual meteorological conditions.

The pilot and his son arrived at a potato field in Phlox, Wisconsin, about 1330 cdt to apply pesticide (Sencor) by aerial application.

After filling the water tank, working on a dirt bike he brought along, and talking with the potato field's owner, the pilot pre- flighted the helicopter, added one quart of oil, and 20 gallons of fuel to the fuel tanks.

The son remembered the aircraft starting normally, noticing nothing out of the ordinary. At this time, the helicopter took off from the dirt road adjacent to the west side of the field. The pilot flew around the immediate area for about 5 minutes before returning to land on the trailer used to transport the aircraft.

About 1830, the pilot and his son mixed the chemicals for spraying, marked the field, and talked while drinking a soda. Then, the pilot started the helicopter, and while it was running and locked onto the trailer, did a walk around inspection.

The pilot's son said his father then made three spraying runs and returned to land because the passenger's door was not closed securely. At this point, the pilot indicated to his son that the cyclic control was sluggish and unresponsive in the forward range.

Once again, the pilot departed to reposition for another spraying run. Both the pilot's son, and a woman watching the aircraft from her backyard agree that while the helicopter was making a right turn, it '...rolled on its right side and crashed into the brush and trees south of the river.'

The pilot's son stated there was no indication of a mechanical problem prior to the accident.

Investigation of the wreckage found the aircraft impacted the ground at a steep angle with the main rotor blades perpendicular to the ground. The aircraft came to rest on its right side, partially buried, in a rocky, swampy, brush covered area directly to the south of the river running through the area.

No anomalies were discovered during engine teardown. There was positive compression, and the magnetos produced spark.

The flight control hydraulic servos were sent to Bell Helicopter Textron, Inc.'s Flight Safety Department in Fort Worth, Texas for inspection. There were no anomalies found during the functional test or teardown inspection.

The cyclic stick controls for the right seat, the seat the pilot was flying from, were different than those for the left seat. The right stick was significantly further back and to the left than the one on the left side. In fact, the son had mentioned to a witness that "...in order to fly the helicopter level, he (the pilot) had to have the cyclic almost full left."

The autopsy report indicated there was generalized and mild Arteriosclerosis present, with no other pre-existing physical anomalies. This condition would have no effect on the pilot's ability to operate the aircraft. The autopsy was conducted at Good Samaritan Health Center, Merrill, Wisconsin.

Toxicological examination revealed no evidence of cyanide, volatiles, or drugs.

NTSB Probable Cause

WAS THE PILOT IN COMMAND'S FAILURE TO MAINTAIN AIRCRAFT CONTROL. A FACTOR TO THE ACCIDENT WAS THE INADEQUATE CYCLIC CONTROL.