On July 3, 1997, approximately 1445 central daylight time, a Bell 206B helicopter, N49661, registered to Omni Geophysical, LLC, and operated by American Aviation, Inc., as a Title 14 CFR Part 133 long-line external load operation, was substantially damaged following a loss of control while repositioning to land near New Iberia, Louisiana. Visual meteorological conditions prevailed, and a company VFR flight plan was filed. The commercial pilot, sole occupant of the aircraft, was seriously injured. During a telephone interview, the pilot reported to the investigator-in-charge that he flew the helicopter from the staging field to a field location to pick up an external load of seismic wire bundles weighing about 300 to 400 pounds. After loading the external basket, he flew the helicopter with the basket attached to a 100 foot long-line cable 2 to 3 miles back to the staging field, and made an approach to the landing area into the wind. He set the basket on the ground; however, he did not release it. He then began to reposition the helicopter to land and shut down. He moved the helicopter to the left side of the basket and then descended laterally to the left approximately 20 feet to a hover height of about 10 feet. As he hovered the helicopter forward about 10 to 15 feet, he felt a jolt. The helicopter nosed down to the left, and came to rest on its right side. The pilot reported to the operator that after he placed the basket in the loading area, he moved laterally monitoring the placement of the external load cable on the ground. He then moved forward and descended attempting to lay the cable out behind the helicopter prior to landing. He further reported that during his descent he looked back and determined the helicopter was approximately 50 to 70 feet from the basket. During a telephone interview, the operator reported to the investigator-in-charge that the company's procedure for repositioning the helicopter to land with the external load attached is that "the cable must remain in visual contact with the pilot at all times." The pilot is to "lay the cable out in front of or to the side of the pilot position in full view of the pilot." Examination of the aircraft wreckage by the FAA inspector revealed that the tailboom was partially separated from the fuselage. The section from the cabin nose to the pilot station was destroyed. The main rotor system was separated from its mast. One main rotor blade was separated about 3 feet from the blade grip/hub assembly, and the outer portion of this blade was embedded in the ground. The commercial pilot successfully completed an initial Part 133 evaluation on June 18, 1997. He accumulated approximately 25 flight hours as an employee of American Aviation, Inc. The pilot reported to American Aviation, Inc., on his pilot application form, that he had a total of 3,126 flight hours in helicopters, of which 211 hours were in the Bell 206B. He further reported that he had 42 hours of experience in long-line external load operations, and zero flight time in the last six months.