On October 1, 2008, about 1840 Pacific daylight time, a Eurocopter AS350 B3 helicopter, N172AE, was substantially damaged during a hard landing at the Blaine Municipal Airport, Blaine, Washington. The helicopter was registered to the US Department of Homeland Security and operated by the Customs and Border Protection (CBP) as a Public Use flight. The commercial pilot and flight instructor were not injured. Visual meteorological conditions prevailed and no flight plan was filed for the local training flight. The flight originated from Bellingham, Washington at 1815. In written statements provided by the CBP, the pilot and flight instructor reported that they were conducting a series of practice emergency procedures during an annual proficiency evaluation flight. After the completion of two landings, the instructor announced that they were going to conduct manual governor operations and positioned the governor switch from "auto" to "man" while on the downwind leg to runway 32. After performing a left 360-degree turn, the pilot initiated an approach to the runway with the intention of performing a slide-on landing. While on final approach to the runway, the pilot stated he felt like he was slightly high and increased the rate of descent "to intercept a flatter approach profile." At an altitude of about 80 feet above ground level (agl), the pilot increased throttle and slightly raised the collective to maintain a "flatter approach profile." Shortly after, he noticed the rotor rpm (NR) starting to slowly decay below the green arc and applied throttle. While NR continued to decay, the low rotor RPM warning horn sounded as NR approached 360 rpm. The pilot continued to increase throttle as NR stabilized at 350 rpm at an altitude of about 40 feet agl. The pilot stated that as the helicopter descended through 20 feet agl, he attempted to increase throttle and collective to arrest the rate of descent when it "felt like the bottom fell out" and the helicopter landed hard on the asphalt runway surface in a slight nose high attitude. The flight instructor reported that he heard the aural low rotor RPM horn sound and noticed the rotor RPM was slowing through 350 rpm as the helicopter was descending through about 20 feet agl. The instructor stated that he positioned his left hand over the left collective twist grip, however, "before I could react to correct the situation," the helicopter struck the ground. The instructor added that he "believes he saw throttle twisting in the decreasing RPM direction" prior to him placing his hand on the twist grip. Examination of the helicopter by a Federal Aviation Administration (FAA) inspector, who responded to the accident site, revealed that the tail boom was partially bent and one of the main rotor blades was damaged. No mechanical anomalies with the helicopter were reported by the commercial pilot or flight instructor.