NTSB Identification: IAD01LA041.
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Accident occurred Sunday, April 08, 2001 in Ringgold, VA
Probable Cause Approval Date: 12/18/2001
Aircraft: Bell BH-206-B, registration: N17HA
Injuries: 2 Minor.
NTSB investigators may have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The pilot/owner prepared to land on an estimated 7 degree slope with the right/uphill skid first. When the right skid made contact with the ground, the helicopter began to rock back and forth longitudinally. The pilot then lifted the helicopter back up into the air, but it nosed forward. To counteract the nose down attitude, the pilot applied aft cyclic, but it did not arrest the situation. The pilot was then concerned about striking trees that were directly in front of him, so he "dropped" the collective to set the helicopter down again. However, the helicopter landed on the front part of the skids, and rolled over onto its nose, and came to rest on its left side. According to Advisory Circular 90-87-Helicopter Dynamic Rollover, "During normal or slope take-offs and landings with the same degree of bank angle or side drift with one skid on the ground, the bank angle or side drift can place the helicopter in a situation where it is pivoting (rolling) about a skid, which is still in contact with the ground. When the uphill slope skid hits the ground, the dynamics of the motion can cause the helicopter to bounce off the upslope skid, and the inertia can cause the helicopter to roll about the downslope ground contact point and over onto its side. The collective should not be pulled suddenly to get airborne, as a large and abrupt rolling moment in the opposite direction will result. This movement can be uncontrollable. If the helicopter develops a roll rate with one skid on the ground, the helicopter can roll over on its side." The pilot reported that there were no mechanical deficiencies.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: pilot's failure to properly control the helicopter during a slope landing, which resulted in a dynamic rollover. Full narrative available
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