Eurocopter AS350B3 crash near Encino, TX, United States

HISTORY OF FLIGHTOn January 10, 2014, about 0815 central standard time, a Eurocopter AS350B3 helicopter, N3948A, impacted trees and terrain after a loss of control near Encino, Texas. The pilot sustained serious injuries and the two crew members sustained minor injuries. The helicopter sustained substantial damage. The helicopter was registered and operated by the United States Customs and Border Protection (CBP), Washington, DC, under the provisions of 14 Code of Federal Regulations Part 91 as a public use flight. Visual meteorological conditions prevailed at the time of the accident and no flight plan was filed. The local flight originated from the McAllen International Airport (KMFE), McAllen, Texas about 0610. According to the pilot, the crew was conducting a law enforcement patrol flight to assist other CBP agents on the ground near Encino, Texas. He flew the helicopter in a left orbit at 800 feet above ground level (AGL). Eventually he descended to 150 feet AGL and hovered on a southerly heading. The helicopter began to drift to the southeast so the pilot repositioned by making a left climbing turn. During the turn, he "felt the wind catch the tail and a slight shimmy" before the helicopter spun rapidly to the left. He applied full right pedal and attempted to accelerate as he believed that he regained control. The helicopter continued the left spin and impacted trees and terrain. Prior to impact with the trees and ground the pilot heard a sound which he recognized as the "low rotor RPM" horn. He reported that there were no preaccident mechanical malfunctions or failures with the helicopter that would have precluded normal operation. According to the two crew members, the wind was strong and gusting during the flight, and was significantly stronger as their altitude increased. The pilot expressed that he was concerned about the wind while maneuvering the helicopter. While the pilot was maneuvering the helicopter in the left-turn pattern about 50-125 feet AGL and felt the helicopter shudder. The helicopter made a quick left rotation and then descended to the ground. They reported the helicopter seemed to be operating normally at the time of the accident and no anomalies were noted. One crew member stated that after impact he secured the fuel cutoff, activated the rotor brake and turned off the electrical master switch. He exited the aircraft and noticed smoke coming from the engine compartment. A witness reported observing the helicopter 50-100 feet above the ground and about 25 feet above the tree tops. The helicopter made an abrupt maneuver and descended into the trees. The helicopter impacted tress and terrain and came to rest on its right side. PERSONNEL INFORMATIONThe pilot, age 28, held a commercial pilot's license for airplane single engine land, airplane multiengine land, and helicopter. He held an instrument rating for airplane and helicopter and was a certified flight instructor for airplane single engine land and airplane multiengine land. He was issued a first class medical certificate on October 23, 2013, with no limitations. As of the accident date, the pilot had accumulated 111 hours in the helicopter make and model; 100 hours were as pilot in command. Further review of the pilots training records revealed that he had not received additional formal mission training from the local branch. He received informal on-the-job training and completed 15 hours of enforcement mission time in a helicopter prior to assignment. Prior to the accident flight the pilot completed two scheduled days off. The pilot reported that his prior training in loss of tail rotor effectiveness (LTE) was helpful during the accident, but more emphasis could have been placed on LTE during training. The second flight crew member, a supplemental air crew member, was seated in the left front seat and was not manipulating the flight controls. The third flight crew member, an air crew rifle operator, was seated in the left rear seat. AIRCRAFT INFORMATIONThe six seat, single-engine helicopter, serial number 4948, was manufactured in 2010. It was powered by a 747-shaft horsepower Turbomeca Arriel 2B1 turboshaft engine. A review of the airframe and engine maintenance logbooks revealed that the airframe and engine both had a total time of 1,397 hours at the time of the accident. The most recent 100-hour inspection was completed on December 13, 2013 at a total time of 1,378.8 hours. The most recent 600-hour inspection was completed on October 8, 2013 at a total time of 1,180 hours. METEOROLOGICAL INFORMATIONAt 0815, the automated weather report for Brooks County Airport (KBKS), which was 10 miles north of the accident reported at: wind from 160 degrees at 10 knots gusting to 14 knots, visibility 10 miles, scattered clouds at 3,600 feet, temperature 19 degrees Celsius (C), dew point 17 degrees C, and altimeter setting 29.89 inches of mercury. The flight crew members reported that the wind in the area of the accident was strong and gusting during the flight. They both reported that the wind was significantly stronger as the helicopter's altitude increased and estimated the wind to be about 15 knots and gusting to 20 knots. AIRPORT INFORMATIONThe six seat, single-engine helicopter, serial number 4948, was manufactured in 2010. It was powered by a 747-shaft horsepower Turbomeca Arriel 2B1 turboshaft engine. A review of the airframe and engine maintenance logbooks revealed that the airframe and engine both had a total time of 1,397 hours at the time of the accident. The most recent 100-hour inspection was completed on December 13, 2013 at a total time of 1,378.8 hours. The most recent 600-hour inspection was completed on October 8, 2013 at a total time of 1,180 hours. WRECKAGE AND IMPACT INFORMATIONThe helicopter wreckage was located on a ranch about 50 miles north of KMFE. The fuselage came to rest on its right side and oriented on a magnetic heading of approximately 290 degrees. Wreckage debris from the helicopter was mostly localized in close proximity of the main wreckage. There was evidence of a postimpact fire which was extinguished by first responders. The helicopter's cabin structure was mostly intact; however, the forward windows were broken and the left rear door was separated. The forward nose, underside fuselage, and right skids were driven into the loose sand and dirt. The tail boom was bent towards the ground at the aft flex-coupling of the forward steel drive shaft. The transmission and main rotor system remained attached to each other and the transmission deck. All the transmission supports arms were broken. The 'Starflex' remained in the center of the rotor hub with two of the arms broken mid-span (red and yellow); one arm was separated from its thrust bearing. Damage to all three main rotor blades was consistent with leading edge ground impact which was perpendicular to the flight path. Two of the blades came to rest in a position that held the helicopter off of the ground. The tail-rotor gear box remained attached to the airframe. One of the tail rotor blades was damaged and separated mid-span with wood debris identified in the leading edge. The other blade was less damaged and both blades remained attached to the hub. The tail-rotor rotated freely when the blades were moved by hand. The tail rotor chip plug was inspected and appeared clean and the oil appeared fresh. The fuel tank remained undamaged and secured within the fuselage; no fuel was observed leaking from the helicopter nor smelled at the accident site. The transmission mounts were broken consistent with impact damage. The fuel cut-off, and rotor brake handles in the cockpit were both extended to the "OFF" position. The right horizontal stabilizer exhibited impact signatures and was separated mid-span. However, the stabilizer structure remained attached by the trailing edge skin. The right stabilizer also exhibited impact signatures consistent with a tree strike. Flight control con