On March 26, 2000, at 1040 central standard time, a Schweizer 300C helicopter, N698SM, sustained substantial damage during landing near New Ulm, Texas. The commercial pilot and passenger were not injured. The helicopter was registered to ADC, Inc., of San Angelo, Texas, and was operated by SkyLane Helicopters, LLC., of Decatur, Texas. Visual meteorological conditions prevailed for the 14 Code of Federal Regulations Part 91 business flight, for which a flight plan was not filed. The local flight departed at 1030 from an off-airport staging area near New Ulm, Texas. The operator and pilot reported to an FAA inspector that the helicopter was transporting the passenger to a remote site to change the batteries on a seismic recorder box. As the pilot terminated the landing approach to a hover, at a skid height of 1 to 2 feet above the ground, an empty canvas bag that was lying on the ground blew into the main rotor system. According to the pilot and passenger, the helicopter developed "a severe vibration and the main rotor system separated from the helicopter." Subsequently, the helicopter impacted the ground in a "moderately hard landing." In the section of the NTSB Pilot/Operator Aircraft Accident Report (Form 6120.1/2) titled "Recommendation (How Could This Accident Have Been Prevented)", the operator stated "making sure that heli-bag [canvas bag] is secure and that aircraft is a safe distance from bag and box." According to the FAA inspector, who examined the helicopter, the main rotor mast housing was fractured just above the top of the transmission case, and the upper portion of the mast housing and the main rotor system separated from the helicopter.