N51990Air Tractor AT-502B · 1999

On April 22, 2014, about 1310 central daylight time, N51990, an Air Tractor 502B, was destroyed when it collided with power lines then terrain while spraying a hay field in Garfield. Kansas. The airline transport rated pilot was fatally injured. The airplane was registered to Farmer's Spraying Service Incorporated, Pratt, Kansas, and operated by Gross Flying Service, Pratt, Kansas. Visual meteorological conditions prevailed and no flight plan was filed for the aerial spraying flight conducted under 14 Code of Federal Regulations Part 137.

A witness stated that he had hired the operator to spray his hay field for weevils. He heard the airplane circle over his field twice then looked out the window where he saw the airplane start its first pass from south to north. The witness then saw a puff of smoke when the airplane struck a set of power lines (about 60 feet tall) that ran east and west along the southern edge of the field. The airplane descended behind a tree line and the witness no longer heard or saw the airplane. He then drove toward where he last saw the airplane and discovered that it had crashed on a dirt road east of the field and called 911. There was no post-impact fire.

A Federal Aviation Administration (FAA) inspector responded to the accident site and said the airplane struck the two very top wires to a set of power lines, which were 3/8-inch-wide steel, static cables. The wires sat about 5 feet below the top of the poles, about 55-feet-above the ground. The airplane crossed over a set of trees before it collided with terrain about 275 feet north of the power lines on a dirt road then traveled about another 145 feet to where it came to rest. There was no evidence the airplane struck the trees; however part of the airplane did impact a large haystack adjacent to the road. The landing gear came to rest about 130 feet forward of where the airplane came to rest. Examination of the airplane revealed wire strike marks on the propeller blades and main landing gear. The pilot remained strapped into the 5-point restraint system and was wearing a helmet with a glare shield.

According to the operator, he stated that he normally handles all of his own spraying jobs, but during busy times he hired the pilot to help him. He said that he and the pilot had four loads to spray on the day of the accident and the accident occurred on the fourth load. He and the pilot discussed breaking for lunch after the third load, but they were excited about "making money" and decided to finish the job. Plus, the wind was picking up out of the south-southeast about 17-18 miles per hour (mph) and they wanted the last field sprayed before it got too windy. The operator added that the previous flights were normal and both airplanes were operating fine. The pilot was in a good mood, not tired, and happy to be flying.

The operator put about 300 gallons of chemicals in the pilot's airplane and then refueled it with fuel from his own fuel-storage tank. The operator did the same with his airplane then they both departed for their respective fields. The operator didn't learn that the pilot had crashed until after he landed.

The operator said that he has sprayed the field where the pilot had crashed numerous times. However, the pilot was not familiar with the field or the surrounding obstacles. The operator described the power lines that the pilot struck as "H Poles." At the very top of the poles were two high-tension ground wires that were "very taught." Below these lines were the power lines that carried electricity. The operator said these lines had a lot of slack in them and sagged "quite a bit". They were also a lot darker than the ground wires and much easier to see. The operator said there was a stand of trees on the opposite side of the street where the power lines were located and it was really difficult to see the top ground wires as you approached the field because "they would get lost in the trees."

The operator also thought that the pilot was most likely setting up his "A and B" lines along the haystack via the onboard GPS when he struck the power lines. The next pass would have been the first spray pass.

The airplane and engine (including the propeller) were examined on June 10, 2014, under the supervision of the National Transportation Safety Board Investigator-in-Charge (NTSB IIC). Examination of the airplane revealed that it had sustained extensive impact damage to the fuselage, wings, and tail section. Flight control continuity was established for all major flight controls to the cockpit. An after-market airbag system was installed on both the left and right shoulder harnesses. Both airbags were out of their respective housing and deflated, indicative that the airbags had deployed upon impact with the ground. No mechanical deficiencies were noted with the airplane or the restraint/airbag systems.

The turbine engine sustained extensive impact damage and was separated in three major sections. Internal examination of the engine revealed deep rotational scoring consistent with it operating at the time of impact. No mechanical anomalies were noted that would have precluded the engine from operating at the time of impact.

The 3-bladed propeller had separated from the engine during impact and all three blades remained in the hub and were loose. One of the blade's tip was missing and never recovered. The fractured end of the blade was curled aft and exhibited 45 degree shearing. The second blade was relatively straight and exhibited rotational scoring on the front of the blade near the tip. The third blade was relatively straight and also exhibited front face rotational scoring near the tip. This damage was consistent with the propeller turning at the time of impact. No mechanical anomalies were noted that would have precluded normal operation of the propeller at the time of impact.

A visit to the accident site revealed that the two top, high-tension cables struck by the airplane had been re-installed by the utility company. It was evident that these top cables were more difficult to see than the lower set of cables, which were much darker in color.