On August 4, 2009, about 1628 eastern daylight time, a Eurocopter AS 350B3 helicopter, N186AE, was substantially damaged while maneuvering at Herlong Airport (HEG), Jacksonville, Florida. The certified flight instructor (CFI) sustained minor injuries and the certificated commercial pilot receiving instruction was not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the instructional flight that originated at Jacksonville Naval Air Station (NIP), Jacksonville, Florida. The helicopter was owned by the US Department of Homeland Security and operated by Customs and Border Protection (CBP) as a public use flight. According to a CBP representative and the pilots, the pilots were practicing maneuvers with the hydraulic system turned off, to simulate a hydraulic system failure. The commercial pilot was conducting a practice approach to runway 25, with a transition to a hover. As the helicopter approached 5 feet above the ground, the commercial pilot began to lose directional control, and requested that the flight instructor take control of the helicopter. The flight instructor assumed control; however, the helicopter entered multiple revolutions, climbs, and descents, before it contacted the ground, spun, and rolled over. The helicopter came to rest about 290 feet south of runway 25, on a magnetic heading about 080 degrees. The fuselage, tail rotor and main rotor drive systems were substantially damaged. Examination of the helicopter by a Federal Aviation Administration (FAA) inspector did not reveal any preimpact mechanical malfunctions; nor did either pilot report any mechanical abnormalities. The CFI reported 2,782 hours of total helicopter fight experience, which included 580 hours in the same make and model as the accident helicopter. The commercial pilot reported 1,154 hours of total helicopter flight experience, which included 12 hours in the same make and model as the accident helicopter. Review of the AS 350B3 flight manual training supplement revealed that practice hovering without hydraulic power was not an approved procedure. The manual stated, in part: "Caution: Do not attempt to carry out hover flight or any low speed maneuver without hydraulic pressure assistance. The intensity and direction of the control feedback forces will change rapidly. This will result in excessive pilot workload, poor aircraft control, and possible loss of control." Winds, reported at an airport located about 5 miles southwest of HEG, at 1550, were variable at 6 knots.