On January 18, 2005, approximately 1615 central standard time, a Schweizer 269D helicopter, N296RL, sustained substantial damage when it impacted the ground following a loss of control while hovering at Stinson Municipal Airport (SSF), near San Antonio, Texas. The certificated flight instructor sustained minor injuries, and the student pilot receiving instruction was not injured. The helicopter was registered to the San Antonio Police Department, San Antonio, Texas. Visual meteorological conditions prevailed and a flight plan was not filed for the 14 Code of Federal Regulations Part 91 public use training flight. The local flight originated at SSF, approximately 1600. In a written statement, the 3,206-hour flight instructor reported that the flight was the first training flight in the helicopter for the student, who is a 55-hour fixed-wing private pilot. The lesson started with an outline briefing of the training flight. The student sat in the right seat, and the instructor sat in the left seat of the dual control equipped helicopter. The instructor pilot reported that he hover-taxied to a grass covered area near the center of the airport to practice hovering with the student. The instructor demonstrated an exercise, which illustrated the function of each flight control, to the student. He then instructed the student to demonstrate the exercise while he held lightly on the controls "due to the difficult nature of the exercise." According to the instructor, the student manipulated the controls for approximately two minutes until the helicopter began to drift left and slightly forward. The helicopter then "suddenly descended," and the instructor began to apply corrective input to the controls as the front left skid struck the ground. The instructor "felt the helicopter begin to roll to the left at this pivot point." He "attempted to correct the situation prior to reaching the critical rollover angle of the helicopter, but the helicopter continued to roll over and came to rest on its left side." The Federal Aviation Administration (FAA) Rotorcraft Flying Handbook (page 11-7) states, "A helicopter is susceptible to a lateral rolling tendency, called a dynamic rollover, when lifting off the surface. For a dynamic rollover to occur, some factor has to first cause the helicopter to roll or pivot around a skid, or landing gear wheel, until its critical rollover angle is reached. Then, beyond this point, main rotor thrust continues the roll and recovery is impossible. If the critical rollover angle is exceeded, the helicopter rolls on its side regardless of the cyclic corrections made." According to the instructor, there was substantial damage to the main rotor, tail rotor, tail boom, and horizontal stabilizer. At 1629, the automated weather observing system at SSF reported wind from 060 degrees at 7 knots, 10 statute miles visibility, overcast clouds at 3,300 feet, temperature 54 degrees Fahrenheit, dew point 32 degrees Fahrenheit, and a barometric pressure setting of 30.47 inches of Mercury.