Date: 201606
Local time of day: 0001-0600
Location: ZZZ.Airport, US
Flight conditions: VMC
Weather elements / visibility: Rain; 8
Light: Daylight
Aircraft: Robinson R44
Operator: Personal
Operating under: Part 91
Flight plan: None
Mission: Utility / Infrastructure
Flight phase: Other Hovering
Airspace: Class G ZZZ
Aircraft component: Main Rotor Blade
Component problem: Improperly Operated
Reporter organization: Personal
Reporter function: Pilot Flying; Single Pilot
Reporter qualification: Flight Crew Instrument; Flight Crew Flight Instructor; Flight Crew Commercial
Human factors: Confusion; Situational Awareness; Time Pressure; Workload; Distraction
Anomaly: Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Fuel Issue; Inflight Event / Encounter Object
Detector: Person Flight Crew
When detected: In-flight
Result: Aircraft Aircraft Damaged; Flight Crew Landed As Precaution; General Maintenance Action
Contributing factors: Aircraft; Weather; Procedure; Human Factors
Primary problem: Human Factors

Narrative: I was drying cherry trees on an orchard which I already dried two times before on the same day. There were five wind machines in the orchard. The first two times I was drying the orchard at a speed of 10 knots groundspeed. When I did it the third time the owner of the orchard asked me to do it at 6 knots this time. When I was passing the second wind machine I must have been too close to the mast of the wind machine. I was already past the mast when I heard two hits (metal on metal). I didn't feel any hit; yaw; or change in power setting. But the noise of the main rotor blades changed to a light whistle and felt some very light vibrations from the main rotor system. Made a precautionary landing right next to the orchard; shut down and inspected the blades for damage. The blade-tip-caps were missing and there was some slight damage to the first half inch of the leading edge of both main rotor blades.Turns out the tips of the rotor blades hit the ladder which is mounted on the mast of the wind machine. I was only one inch too close to that ladder. The helicopter had to be put on a trailer and was shipped to the next repair center for inspection. The problem was most likely that I was flying at 10 knots on the first two times I dried the orchard that day and then had to slow down to 6 knots on the third time. That might have made me think I'm already past that mast and I came back to the tree row a little bit too early. Another thing was that I was worried about; if I had enough fuel in case the owner wanted me to do another pass over his orchard after I did it already three times. That might have distracted me from my task to fly safely over the trees and stay far enough away from the obstructions.Next time I have to focus on keeping my distance from all obstacles (even though it seems like I've already passed them) and don't let anything distract me from my job. Worry about the fuel calculation when on the ground.




Synopsis: A R44 pilot reported flying too close to a wind machine while low and slow drying cherry orchards. His rotors hit the wind machine damaging them. The pilot landed; discovered the damage and trucked the helicopter to a maintenance facility.