History of Flight
On August 3, 2020, at 1941 eastern daylight time, an Airbus EC130-B4 helicopter, registration N55GJ, was substantially damaged when it impacted the Tennessee River near Knoxville, Tennessee. The helicopter was being operated as a Title 14 Code of Federal Regulations Part 91 personal flight. One passenger was fatally injured; the pilot and two other passengers were not injured.
The flight departed McGhee Tyson Airport (TYS) at about 1826 for a local area flight. According to the pilot, about 1940 he made a right circling approach over the river toward a landing site on his property near the river's edge. He stated he was descending with low power and a 25° angle of descent, planning to come to a hover at low speed over the water and then hover taxi to the landing site at a height of about 75 feet above the water. When he added power to arrest the descent, the helicopter "started to settle." He pulled maximum power to stop the settling, but it continued to descend until impacting the river.
A witness on a neighboring property reported seeing the helicopter hover low over the water longer than usual before tilting toward the south and descending into the water. A passenger stated that the helicopter descended in a level attitude, then the left skid struck the water, followed by the rotor, and the helicopter was torqued into the water on the left side. The pilot and two passengers egressed before the helicopter sank; one passenger was unable to egress and was later recovered by first responders.
A pilot who had previously flown with the accident pilot spoke to him the morning after the accident. The accident pilot recalled that he was making a steep approach, coming in vertically with little-to-no airspeed, and estimated a descent rate greater than 300 feet per minute.
Aircraft Information
The helicopter's gross weight at the time of the accident was estimated at about 4,440.2 lbs, based on the flight manual and weight and balance chart. The maximum gross weight per the manual was 5,350 lbs. Longitudinal and lateral center of gravity locations were within flight manual limits.
Wreckage and Impact Information
Examination of the accident site by a Federal Aviation Administration (FAA) inspector revealed the helicopter came to rest on the bottom of the Tennessee River approximately 435 feet at a bearing of 149° from the intended landing site. The fenestron (tail rotor shroud) was recovered floating nearby.
The helicopter was recovered mostly intact. Damage included a large hole in the left side windshield, the left door window broken out, damage to all rotor blades consistent with water impact, and two of four suspension bars fractured midspan. The tailboom remained attached to the fuselage, and the fenestron separated from the tailboom just aft of the ring frame.
Examination of the airframe and flight control system revealed no evidence of pre-impact failure or mechanical malfunction that would have precluded normal operation. The pilot reported no mechanical malfunctions or failures prior to the accident sequence. The helicopter was equipped with a vehicle and engine monitoring display and a digital engine control unit that stored failure messages. The data showed no failures or limit exceedances prior to impact and indicated the engine was running at impact. All failure indications occurred around the time of impact, and no preimpact anomalies were noted with the engine that would have precluded normal power production.
Additional Information
The FAA's Helicopter Flying Handbook (FAA-H-8083-21B) describes vortex ring state (formerly settling-with-power) as an aerodynamic condition where a helicopter may be in a vertical descent with 20 percent up to maximum power applied and little or no climb performance. Conditions conducive to vortex ring state include hovering out of ground effect (OGE) without precise altitude control, and steep approaches with a tailwind component. The combination of a vertical or nearly vertical descent of at least 300 fpm, rotor disk using 20–100 percent of available engine power, and horizontal velocity slower than effective translational lift is likely to cause settling in a vortex ring state. Recovery traditionally involves increasing airspeed and/or partially lowering collective; in most helicopters, lateral cyclic thrust combined with increased power and lateral antitorque thrust produces the quickest exit. The accident helicopter's rotor diameter was 35 feet 1 inch; hovering more than one rotor diameter above the surface is considered OGE.