History of Flight
On May 29, 2011, about 1145 central daylight time, a Eurocopter AS 350 B2 helicopter, registration N747CH, impacted terrain while on approach to Fort Worth Alliance Airport (AFW), Fort Worth, Texas. The private rated pilot, flight instructor, and passenger received minor injuries. The helicopter was substantially damaged during the accident and a postcrash fire ensued. The aircraft was registered to and operated by Sovereign International Equities, LLC, Portland, Oregon, under 14 Code of Federal Regulations Part 91 as an instructional flight. Visual meteorological conditions prevailed; the flight operated without a flight plan.
The pilot had recently purchased the helicopter. The certified flight instructor (CFI), employed by the helicopter's previous owner, was to help ferry the helicopter from Puerto Rico to Texas and then provide flight instruction to the new owners.
The CFI reported that he was giving the pilot instruction in normal and emergency procedures. During the last traffic pattern, the hydraulic system was turned off to simulate a hydraulic system failure. The CFI added that the ground controller reported they were on the wrong radio frequency, so he corrected it. During the approach, the helicopter slowed and started a left yaw. The CFI stated that he tried to regain control by adding right pedal, looking for forward airspeed, and reducing power. The helicopter did not respond to the CFI's control inputs, descended, and impacted terrain.
Personnel Information
The CFI held commercial pilot and flight instructor certificates for rotorcraft-helicopter and a private pilot certificate for airplane single-engine land. His last first-class FAA medical was issued on May 28, 2010. The CFI reportedly had approximately 3,466 total flight hours and about 789 hours in a Eurocopter AS 350.
The pilot in the right seat held a private pilot rotorcraft-helicopter rating. His FAA third-class medical was issued on August 23, 2010. The pilot's logbook was not located; he estimated total flight time at 4,200 hours, with about 9 hours in the accident helicopter.
The rear-seat passenger held private pilot certificates for airplane single-engine land and rotorcraft-helicopter ratings.
Aircraft Information
The accident helicopter was a 2004 Eurocopter AS350B2 "A-star," a single-engine helicopter powered by a Turbomeca Arriel turboshaft engine. The helicopter had been purchased from Caribbean Heli-Jets, Puerto Rico, by the LLC. Under the previous owner, it was maintained per the manufacturer's recommended plan and had accumulated approximately 2,168 hours.
Meteorological Information
The automated weather station at KAFW reported at 1145: wind from 160 degrees at 20 knots, gusting to 27 knots; temperature 86°F; dew point 68°F; visibility 10 miles; clear sky; altimeter 29.76 inHg.
Communications and Radar
The pilots were in contact with the AFW tower controller. During traffic pattern work, the private pilot inadvertently contacted ground control; the ground controller advised they were on the wrong frequency. Otherwise, communications with AFW tower were routine, and no emergency or distress calls were received. Alliance approach radar did not display the accident helicopter during its traffic pattern work or the accident sequence.
Wreckage and Impact Information
FAA inspectors examined the wreckage on-site. All major components were accounted for. The main wreckage came to rest on its right side. The right side skids were torn from the fuselage, the tailboom horizontal stabilizers were damaged, the main rotor blades remained attached but exhibited severe impact and heat damage; one of the two tail rotor blades separated on impact. A postcrash fire partially consumed the cabin area.
Tests and Research
The NTSB IIC, FAA inspectors, and technical representatives from the airframe and engine manufacturers examined the wreckage after recovery at a salvage yard. The examination did not reveal any preimpact mechanical malfunctions.
The helicopter's 30 alpha switch central console and caution warning panel were sent to the NTSB Materials Laboratory for further examination. Both units received heavy thermal damage from the postcrash fire. The Materials Laboratory examination revealed some evidence of filament sagging on several bulbs, most likely due to age. There were no broken filaments and no evidence of hot filament stretching. The position of the push-type buttons on the systems control panel could not be determined due to fire damage.
Additional Information
According to the Eurocopter AS 350 B2 Flight Manual (Emergency Procedures) and Flight Manual Supplement, Hydraulic Pressure Failure Training Procedures: To simulate a loss of hydraulic power, depressing the "HYD TEST" pushbutton produces the same effects as a real failure: the hydraulic pump pressure is bypassed; the main rotor accumulators give limited time hydraulic assistance backup; the red HYD light comes on, the horn sounds. The simulation is the same as a real failure except that the main rotor load compensator is depressurized and tail rotor pedal control feedback forces are higher than normal when pushing on the right pedal.
The manual notes: "The instructor must ensure that the 'HYD TEST' pushbutton is selected OFF (upper position) before the collective hydraulic cut-off switch is selected OFF to ensure that the tail rotor compensator is pressurized, and to enable the pilot to restore the hydraulic power system by resetting the hydraulic cut-off switch to ON during the training exercise should it become necessary."
The manual also notes that the hydraulic failure safety speed is 40 to 60 knots and states: "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."