History of Flight
On October 4, 2014, about 0155 central daylight time, N335AE, a Bell 206L1+ helicopter, was destroyed by post-impact fire after it impacted terrain while on approach to the United Regional Hospital helipad in Wichita Falls, Texas. The commercial pilot was seriously injured; the flight nurse, paramedic, and patient died. The helicopter was registered to and operated by Air Evac EMS, Inc., O'Fallon, Missouri. A company visual flight rules flight plan was filed for the patient transfer flight that departed Jackson County Hospital, near Waurika, Oklahoma, about 0133. Visual meteorological conditions prevailed.
A witness, a photojournalist, observed the helicopter hovering over 10th and Grace Streets at about the height of the hospital (100-120 feet). He then saw it begin to spin to the right, descend, and disappear behind a building. Sparks were seen, and he called 911.
The pilot stated that after a previous flight, he received a call to transport a patient from Waurika to Wichita Falls. The flight to Waurika was uneventful. After a 20-minute engine-running ground time, they departed for Wichita Falls. The pilot used night-vision goggles en route but flipped them up near the hospital due to ground lighting. He performed a high recon, then initiated an approach from the northwest. He felt fast (about 12-15 knots) and high, so he aborted. He added power and pulled collective, after which the helicopter entered a rapid right spin. Despite control inputs, the spin continued. The helicopter struck the ground inverted and caught fire.
Data from a Sky Trac system showed that during the last 43 seconds, the helicopter descended from 202 feet to 152 feet, decelerated to about 5 knots, then turned right, descended to 54 feet, and increased speed to 17 knots before data ended. Hospital surveillance video showed a descending right-hand turn and impact at 0154:56, followed by an explosion six seconds later.
Another Air Evac crew based at the hospital heard a change in rotor noise, then a snap and bang. They responded to find the helicopter upside down and on fire. The flight nurse was lying about six feet away, on fire; the paramedic was crawling out; the pilot was crawling out of the front. The patient was inaccessible due to fire.
Personnel Information
The pilot held a commercial pilot certificate for rotorcraft-helicopter and instrument rating. Total flight time was 1,810 hours, with 1,584 hours in helicopters (214 in the Bell 206). His last FAA second-class medical was issued May 13, 2014, without limitations. He was also a chief warrant officer in the U.S. Army, trained in CH-47D helicopters.
He came on duty October 2, 2014, at 1810, after six days off. He had made one flight prior to the accident flight.
He was hired June 9, 2014, and completed initial training including 10.9 hours of flight training, covering normal and emergency procedures including loss of tail rotor effectiveness. He passed a proficiency check on June 22, 2014. Additional base orientation training included 5 flight hours and 2 hours of night flying to local hospitals.
Meteorological Information
Weather at Sheppard Air Force Base/Wichita Falls Municipal Airport, about 5 miles north, at 0152: wind 140 degrees at 3 knots, visibility 10 miles, clear skies, temperature 51°F, dewpoint 33°F, barometric pressure 30.24 inHg.
Helipad Information
The United Regional Hospital's ground-level helipad was 60 ft by 60 ft, privately owned. At the time of the accident, it was clear of obstacles.
Aircraft Information
The single-engine, seven-place helicopter was manufactured in 1981, equipped with a Rolls-Royce C-250-30P engine. It was configured for air medical transport. The airframe had about 18,378.6 total hours; engine about 3,546.2 hours. The helicopter was retrofitted with Van Horn Aviation composite tail rotor blades (Supplemental Type Certificate SR02249LA). Estimated gross weight at accident was 4,274 pounds, about 176 pounds below maximum gross weight of 4,450 pounds.
Wreckage and Impact Information
The helicopter collided with power lines and came to rest inverted between two trees about one block northwest of the helipad. All major components were at the main impact site. The wreckage was extensively burned and fragmented. The tail boom separated from the fuselage. Tail rotor blades had minor leading edge damage. Control continuity was established for main flight controls; no pre-mishap mechanical anomalies were observed that would have precluded normal operation. The right anti-torque pedal was displaced about 50-75% at impact. The engine sustained extensive thermal damage but no pre-mishap anomalies were noted.
Medical and Pathological Information
Toxicological examination of pilot blood specimens taken at the hospital was negative for all tested items.
Additional Information
The FAA Advisory Circular 90-95 describes loss of tail rotor effectiveness (LTE) as an aerodynamic condition resulting in uncommanded rapid yaw at airspeeds less than 30 knots. LTE is not related to maintenance malfunction and can be influenced by factors such as main rotor downwash, rotor tip vortices, turbulence, and low airspeed. The Rotorcraft Flying Handbook (FAA-H-8083-21A) defines LTE as an uncommanded yaw toward the advancing blade, caused by aerodynamic interaction, not mechanical failure.