N353HW

HISTORY OF FLIGHTOn October 22, 2013, about 0605 central daylight time (CDT), a Eurocopter AS 350 B3, N353HW, impacted trees and terrain near Somerville, Tennessee. The certificated commercial pilot, a registered nurse, and a respiratory therapist were fatally injured; the helicopter was destroyed by impact forces and a post-crash fire. The helicopter was registered to and operated by Memphis Medical Center Air Ambulance Service, doing business as Hospital Wing, under the provisions of 14 Code of Federal Regulations Part 91, as a positioning flight. The flight operated on a company visual flight rules flight plan. The flight originated from Hospital Wing Heliport (2TN0), Memphis, Tennessee, at 0547 and was en route to Whitehurst Field Heliport (60TN), Bolivar, Tennessee.

According to company personnel, the accident pilot arrived for work about 1730 on October 21 and began his flight planning procedures, which included a review of the local area weather and completion of the company's risk assessment checklist. About 0025 on October 22, a call came in to company, requesting helicopter services to Piperton, Tennessee to pick up a patient. The pilot completed a weather check at 0026 and the flight departed 2TN0 at 0035. About two minutes later, the pilot aborted the flight and returned to 2TN0 due to low ceilings. The flight was cancelled due to weather.

At 0137, another call was received by the company for helicopter services in Olive Branch, Mississippi. The accident pilot declined the flight due to weather.

At 0500, another request for helicopter services was received by the company, to pick up a patient at 60TN and transport him to Memphis. Dispatch records indicated that the accident pilot performed a weather check at 0500 and the flight was dispatched at 0503. According to satellite tracking data provided by the operator, the helicopter departed 2TN0 at 0547 and proceeded in an easterly direction, following U.S. Highway 64. About 18 minutes later, the helicopter was observed in a climb and in a right turn away from the observed course. The last data point indicated that the helicopter was on a course of 146 degrees and at 98 knots ground speed and at an altitude of 1,560 feet above mean sea level (msl) or about 1,116 feet above ground level (agl).

The operator dispatched two aircraft to the last known position of N353HW after the pilot did not make the normal 10-minute position report. One of the pilots observed a fire in a rural area about 19 miles west of 60TN. First responders confirmed that the helicopter had crashed at that location.

Several local residents were interviewed after the accident. They reported hearing a helicopter in their vicinity near the time of the accident; however, no one reported hearing the helicopter crash. Also, no eyewitnesses to the accident were found. Their statements are included in the public docket for this accident investigation.

PERSONNEL INFORMATION

The pilot, age 47, held a commercial pilot certificate with ratings for rotorcraft-helicopter, instrument-helicopter, and airplane single engine land. According to the operator, his total flight experience was 2,441 hours, including 521 hours in the accident helicopter make and model, and 2,250 hours in rotorcraft. His flight experience during the 90 days prior to the accident was 33 hours, including 10 hours in the 30 days prior to the accident.

According to the operator, the pilot flew previously with the Memphis Police Department (MPD), where he accumulated about 400 hours in the AS 350. He received all of his night vision goggle (NVG) training and experience at Hospital Wing, since MPD did to utilize NVG.

Training records provided by the operator revealed that the pilot completed AS 350 B3 initial training (ground and flight) on October 31, 2012. Ground training consisted of 51 hours and flight training consisted on 12.1 hours, including 5.8 hours with NVG. The training was conducted "in house" by the Hospital Wing Chief Pilot. The training included inadvertent instrument meteorological conditions (IMC) scenarios in a simulator.

Several company pilots, supervisors, and nurses were interviewed following the accident. In general, the accident pilot was described as a good pilot, well-liked by the other company pilots and medical staff, and conscientious. He flew "by the book," did not "press" the weather, and utilized the company's risk assessment tools.

AIRCRAFT INFORMATION

The accident helicopter was a Eurocopter AS350 B3 model that was manufactured in 2001. It was equipped with a three-blade main rotor system and a two-blade tail rotor system and was powered by a Turbomeca Arriel 2B engine rated at 871 shaft horsepower. The helicopter was purchased new by the operator.

The helicopter was equipped with skid-type landing gear, NVG and NVG-compatible lighting, an Aspen Avionics 1000H primary flight display/multi-function display (PFD/MFD), a vehicle engine multifunction display (VEMD), an autopilot, an enhanced ground proximity warning system (EGPWS), and a Thales/Sextant Digital Electronic Control Unit (DECU). The helicopter was not equipped for flight under instrument flight rules.

According to the operator, the helicopter was maintained under the manufacturer's inspection program. The last recorded aircraft time was 6,391.1 hours on October 13, 2013. The most recent aircraft inspection occurred on October 11, 2013, which was a 30-hour inspection. The last annual inspection occurred on July 17, 2013, at 6,274.3 hours.

METEOROLOGICAL INFORMATION

The closest weather observation facility to the accident site was Fayette County Airport (FYE), located about 1.5 nautical miles (nm) south-southwest of the accident site. The airport elevation was about 436 feet msl. The 0556 surface weather observation (about 9 minutes prior to the accident) included a broken ceiling at 1,600 feet agl, wind from 030 degrees at 4 knots, visibility 10 statute miles or greater, temperature 11 degrees C, dew point minus 1 degrees C, and altimeter setting 30.05 inches of mercury.

The FYE observation about 2 minutes after the accident, at 0607, included calm wind, few clouds at 800 feet agl, a broken ceiling at 1,200 feet agl, a broken ceiling at 6,000 feet agl, visibility 10 statute miles or greater, temperature 11 degrees C, dew point minus 1 degrees C, and altimeter setting 30.05 inches of mercury.

The Memphis International Airport (MEM) observation (5 nm SE of 2TN0), at 0554 (about 3 minutes prior to takeoff) included wind from 010 at 7 knots, few clouds at 1,200 feet agl, scattered clouds at 4,700 feet agl, overcast ceiling at 5,500 feet agl, and visibility 10 statute miles or greater.

Official sunrise at Somerville, on October 22, 2013 was about 0710 and civil twilight was about 0644.

WRECKAGE AND IMPACT INFORMATION

The aircraft wreckage debris was located in a wooded area surrounded by cotton and soybean fields, approximately 3,300 feet south of U.S. Highway 64, in Somerville. The accident site elevation was about 372 feet. The majority of the aircraft structure, including the cockpit, instruments and controls, was burned and consumed by impact forces and a post-impact fire. The VEMD exhibited extensive thermal damage during the post-crash fire and further examination was not attempted. The helicopter impacted trees prior to impacting the ground. The energy path was generally oriented on a magnetic heading of about 090 degrees and was about 100 feet in length. The flight path angle, measured from broken trees to the initial impact crater, was about 50 degrees. All static and dynamic components of the helicopter were accounted for at the accident site.

All three main rotor blades exhibited signatures consistent with powered impact strikes throughout the length of the blades. The red and yellow blades showed more extensive damage, where impact forces resulted in blade delamination. Severe fraying was also observed at the outboard tips of all three blades.

The tail boom was consumed by a post-impact fire and the horizontal stabilizers exhibited both thermal and impact damage. The vertical stabilizer and vertical fin were consumed by fire. The engine output-to-tail rotor drive shaft flange remained bolted to the engine; however, all three flange tangs that attached to the flex couplings were bent and pulled aft and separated at the flex coupling. The splined coupling remained attached to the flex coupling on the tail rotor forward steel drive shaft. The splined portion on the tail rotor drive shaft was separated with no visible anomalies to the splines. The length of the tail rotor drive shaft was bent in a "u" shape, approximately mid-span from impact forces and was broken just aft of the third hanger support bearing. The aft section of the drive shaft was separated and partially damaged from post impact fire and was separated at the aft flexible coupling flange. The aft flange mount was thermally separated from the tail rotor drive shaft; the flexible couplings were intact to the coupling system but broken away from the tail rotor gearbox forward mounts.

Both tail rotor blades remained attached to the tail rotor gearbox; there was no visible impact damage observed to the leading edges; however, both blades exhibited thermal decomposition. The hub could not be pulled off the shaft due to thermal damage; however, the woodruff key appeared to be in place when the nut was removed. The gearbox oil cap was melted away and the oil was consumed. Subsequent disassembly of the tail rotor gearbox revealed no anomalies except for post-crash fire signatures. No metallic debris was observed on the chip detector. The yaw load compensator was observed to be thermally damaged and separated from the helicopter and was found within the main wreckage area.

Flight control continuity could not be confirmed due to post-crash fire damage. The cyclic, collective, and anti-torque pedals were found lying loose in the cockpit area of the fire-c...