Primary finding
Probable cause
The inadvertent entanglement of a long line with the skid, which resulted in a loss of flight control. Contributing to the accident was the use of nylon lines instead of steel cables to secure the bucket.
Investigator assessment
Analysis narrative
During an aerial application reconnaissance flight, the helicopter departed with a fertilizer bucket attached which was held on by three nylon lines. As the helicopter lifted off and climbed out, the pilot noticed initially that all three nylon lines were hanging downward and moving appropriately with the bucket. The pilot continued to climb out and turned slightly to the right, away from obstacles. However, at this time, the pilot realized that the helicopter was not responding correctly to his flight control inputs. Looking in the mirror, he noticed that the bucket was hanging at a 45° angle and that one of the nylon lines connected to the bucket was wrapped over the right front skid and up against the cross-tube. The helicopter remained in a constant right turn and the pilot struggled to maintain control. He then attempted to release the bucket, but subsequently the helicopter impacted terrain and sustained substantial damage to the fuselage and main rotor blades. The pilot reported no preimpact mechanical anomalies or malfunctions that could have precluded normal operation. He further stated that the nylon lines used to secure the bucket were lighter weight than the steel cable lines normally used and moved substantially in the airflow.