Uvalde, TX, USA
N417WT
Bell 206
The pilot and two passengers onboard the turboshaft-powered helicopter departed from a private ranch on a night cross-country flight in visual meteorological conditions. Video evidence from witnesses who observed the departure showed that bright flood lights were shown directly at the helicopter during the departure. The helicopter impacted terrain shortly after takeoff about 100 ft below the top of a 1,500-ft hill and about 5 miles east of the departure point. An automated weather station, located 13 miles southeast of the departure site, at 0015 recorded, clear skies, and an altimeter setting of 29.97 inHg. A review of weather information about the time of the accident revealed a small area of cloud ceilings east of the departure point. Based upon the helicopter's recorded route of flight, it is unlikely that the helicopter encountered this area of reduced visibility/ceilings. Examination of the helicopter revealed no evidence of any mechanical malfunctions or anomalies that would have precluded normal operation. Data from the helicopter's flight displays revealed that the helicopter's altimeter was set at 30.05 inches of mercury (inHg); The altimeter setting at the station nearest the accident site was 29.97 inHg. This difference would have resulted in the helicopter's altimeter indicating a higher altitude than the helicopter's actual altitude. The display's data also indicated the helicopter's flight path towards its destination airport. The flight display's last indicated altitude was 1,538 ft, which would have only provided marginal obstacle clearance. Additionally, the helicopter's terrain avoidance and warning system low altitude alerts were set to "inhibit", or turned off; therefore, the pilot would not have received a terrain warning message. Flight information from the displays did not record any evasive maneuvering, and it is likely that the pilot did not see the terrain before impact. Autopsy and toxicology testing of the pilot did not reveal evidence of incapacitation. A review of the pilot's medical information indicated that he had been diagnosed with early cataracts; the pilot first reported cataracts to the FAA in 2005, and it is possible that they could have increased in severity enough to have compromised his night vision and contributed to his difficulty avoiding the hill. Additionally, the pilot's eyesight may not have adjusted to the night conditions after being exposed to bright lights during departure. However, the severity of his cataracts at the time of the accident is unknown, and whether visual limitations from cataracts or bright lights contributed to the accident, could not be determined. The accident is consistent with control flight into terrain during dark night conditions
HISTORY OF FLIGHT On November 3, 2018, about 2347 central standard time, a Bell 206B helicopter, N417WT, was destroyed when it was involved in an accident near Uvalde, Texas. The pilot and two passengers were fatally injured. The helicopter was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. Night visual meteorological conditions prevailed at the time of the accident. A review of data from the helicopter's primary and multifunction display units revealed that the helicopter departed a private ranch about 2341 and proceeded east toward San Antonio, Texas. The data showed that the helicopter reached an altitude of 1,900 ft before beginning a gradual descent, until the final barometric altitude of 1,538 ft (indicated altitude on the display) and 74 knots airspeed. The altimeter was set for a barometric pressure of 30.05 inHg. The data did not reveal any extreme changes in pitch, bank, or airspeed. The flight display also retained the last GPS altitude, which was 1,422 ft. Additionally, the terrain awareness warning system (TAWS) and helicopter TAWS low altitude alerts were set for 140 ft above ground level; however, terrain alerts were set to "inhibit." Figure 1. Helicopter departure with flood lights shining on helicopter (Video screenshot from KSAT and Jason Martinez). The Uvalde County Sherriff's Office was notified of a possible downed aircraft northwest of Uvalde, Texas. A search effort of authorities and local volunteers found the wreckage about daybreak the following morning. The helicopter impacted the side of a hill about 5 miles east of the departure point and about 71 miles west of San Antonio International Airport. PERSONNEL INFORMATION A review of previous aviation medical examinations noted a diagnosis of early cataracts; however, there was no additional information regarding the severity of the condition. METEOROLOGICAL INFORMATION A review of weather information about the time of the accident revealed a small area of cloud ceilings east of the departure point. This area of clouds dissipated and moved eastward over time. There was no indication of low-level wind shear or clear air turbulence. There was no record of the pilot receiving a weather briefing before departure. Moonrise occurred at 0343 and moonset at 1642 with about 19% disk illuminated. At the time of departure and the accident, the moon would have been below the horizon. <span style="color: black;"></span> WRECKAGE AND IMPACT INFORMATION The helicopter impacted about 100 ft below the apex of a hill that measured about 1,500 ft mean sea level (see figure 2). A wreckage path about 75 to 100 yards long was distributed along the hillside leading to the main wreckage. There was no post-crash fire. Figure 2. Wreckage at the accident site (Courtesy of FAA) The hazardous terrain at the accident site precluded an on-scene examination of the helicopter; the wreckage was recovered to a secure facility for examination. All major components of the helicopter were located at the accident site. The forward portion of the cabin/cockpit area was largely destroyed by impact. The tail boom remained attached to the fuselage but was twisted and damaged due to the impact. The fuel bladder remained in the fuselage and contained an undetermined quantity of fuel. The tail rotor gearbox was found several feet away from the tail boom. Both tail rotor blades were bent near the doubler but remained attached. The tail rotor was rotated by hand with no binding or anomalies noted with the tail rotor gearbox. Oil was present in the tail rotor gearbox. The tail rotor gearbox's magnetic chip detector was removed and no particles were observed. The main rotor hub and blade assembly had separated from the main rotor mast below the main rotor hub. The main rotor mast exhibited a fracture consistent with mechanical overload. The two main rotor blades were fractured outboard of the doublers and located near the wreckage path. Main rotor drivetrain continuity was established by rotating the input drive by hand and observing the rotation of the mast. No abnormalities were noted when the transmission was rotated by hand. The transmission chip detectors were removed and no particles were observed. The components of the hydraulic system, including the hydraulic pump, sustained various degrees of impact damage. A small amount of hydraulic fluid was present in the hydraulic oil reservoir. The three servo actuators remained attached to the roof structure, and movement was noted when manipulated by hand. No preimpact abnormalities were noted with hydraulic system. Flight control continuity could not be established due to impact damage; however, no anomalies were noted with the collective, cyclic and anti-torque pedals. No evidence of pre-impact abnormalities were noted during the airframe examination. The engine was removed from the airframe and transported to an overhaul facility for a detailed examination. The engine was placed on a stand and disassembled. Continuity through the accessory section was established. Foreign object damage was noted to the leading edges of the intake compressor blades; also "metal spray" was noted on the turbine compressor wheel. The engine bleed valve and fuel nozzle were bench tested. The power turbine governor and fuel control units were sent to another facility and tested. No engine abnormalities were noted that would have restricted normal operation of the engine. MEDICAL AND PATHOLOGICAL INFORMATIONThe Bexar County Medical Examiner's Office, San Antonio, Texas, conducted an autopsy on the pilot. The cause of death was determined to be "multiple blunt force injuries." The FAA Forensic Sciences Laboratory conducted toxicological testing of the pilot. The specimens were not tested for cyanide and carbon monoxide. The test was negative for ethanol; desmethylsildenafil was detected in the muscle and liver. Desmethylsildenafil is an active metabolite of sildenafil, which is not considered to be impairing.
The pilot's controlled flight into terrain during night visual meteorological conditions. Contributing to the accident was the pilot improper decision to inhibit the helicopter's terrain warning systems and flight at low altitude.
Source: NTSB Aviation Accident Database
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