Globe, AZ, USA
N617LH
EUROCOPTER AS350BA
During a night vision goggle (NVG) training flight, the flight instructor initiated a simulated hydraulic failure on the downwind leg for landing. The flight instructor stated that during this maneuver, the pilot receiving instruction did not properly adjust the trim and did not maintain sufficient air speed. The helicopter slowed to about 20 knots, which was half the speed the flight instructor expected. When the flight instructor heard what he believed to be the low rotor horn and heard the pilot exclaim “uh-oh,” the flight instructor tried to regain control of the helicopter; however, the helicopter impacted the ground hard. Interviews with the pilot and instructor established that both were manipulating the controls after the initial loss of control and that no positive exchange of control had occurred. The pilot reported that the last time he had performed a simulated hydraulic failure was almost 1 year before the accident and that he had never performed such a procedure or had one demonstrated while operating with NVGs. The pilot and instructor reported no in-flight abnormalities with the helicopter before the initiation of the simulated hydraulic failure, and postaccident examination of the hydraulic system components revealed no abnormalities that would have precluded normal operation.
On November 4, 2009, about 1930 mountain standard time (MST), an American Eurocopter Astar AS350BA, N617LH, landed hard during a training flight at San Carlos Apache Airport (P13), Globe, Arizona. Omniflight Helicopters, Inc., was operating the helicopter under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The certified flight instructor (CFI) and the commercial pilot undergoing instruction (PUI) sustained serious injuries. The helicopter sustained substantial damage to the tailboom, fuselage, main cabin, and main rotor blades. The cross-country instructional flight departed Phoenix, Arizona, about 1845. Visual night meteorological conditions prevailed, and a company flight plan had been filed. The pilots reported that during a Night Vision Goggle (NVG) initial training flight, while performing a simulated hydraulics failure, which was initiated while on downwind in the traffic pattern at P13, they lost control of the helicopter and subsequently impacted the ground. The pilots both submitted written statements and were interviewed. The helicopter was in the pattern on the downwind leg when the CFI told the PUI that the CFI was going to execute a simulated hydraulic failure by activating the hydraulic test switch. After activation of the hydraulic test switch, the PUI decelerated to just below 58 knots, and the CFI deactivated the hydraulic test switch and waited until the hydraulic (HYD) warning light went out. The CFI told the PUI to turn off the hydraulics with the isolation switch and to make a shallow approach to a run on landing. The PUI acknowledged and turned off the hydraulic system with the isolation switch on the collective. The PUI then started a right turn towards the final approach, but, according to the CFI, the PUI was not correcting trim or airspeed. The CFI noted that the PUI slowed to about 20 knots. The CFI expected to see the airspeed closer to 40 knots at this point of the maneuver, so he made a slight forward cyclic input to try and increase speed, but he was primarily verbally instructing the PUI to make the needed corrections. At this time, the CFI observed that the nose of the helicopter was left of their flight path. The helicopter nose then started to tuck and rolled to the left. The CFI heard what he thought was the low rotor horn and the PUI exclaim something to the effect of “uh-oh.” The CFI then attempted to recover control of the helicopter by getting onto the controls and stated, “I have the controls.” The instructor told the PUI to turn the hydraulics back on. The helicopter continued in a nose low attitude and in a left bank of about 15-30 degrees. The pilots both stated that they could not move the cyclic in the lateral axis. The helicopter continued the rotation with the nose low attitude until ground impact. Post-accident interviews with both of the pilots established that both were manipulating the controls after the initial loss of control, and that a positive exchange of controls had not occurred. The pilot’s reported no in-flight abnormalities with the helicopter prior to the initiation of the simulated hydraulic failure. The pilot receiving instruction reported that the last time he had performed a simulated hydraulic failure was on November 20, 2008. He reported that he had never performed, or had a simulated hydraulic failure demonstrated, while operating using NVG’s. On November 9 and 10, 2009, the wreckage was examined by the investigation team. Continuity for the flight controls was established, and it was determined that the damage to the flight control system was a result of impact forces. The hydraulic servos were removed from the helicopter for further examination. On December 1, 2009, the servos from the accident helicopter were examined at the facilities of Hawker Pacific Aerospace, Sun Valley, California. A copy of the test results are on file in the docket. The testing revealed no abnormalities that would have precluded normal operations.
The pilot receiving instruction’s failure to maintain adequate airspeed or control of the helicopter during a simulated hydraulic failure maneuver, which resulted in a hard landing. Contributing to the accident was the flight instructor’s delayed remedial actions and the lack of a positive exchange of control.
Source: NTSB Aviation Accident Database
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