N16760

HISTORY OF FLIGHTOn April 4, 2016, about 1610 eastern daylight time, a Bell 206L, N16760, was destroyed when it impacted terrain while maneuvering following a loss of engine power in Pigeon Forge, Tennessee. The commercial pilot and four passengers were fatally injured. The helicopter was registered to a private individual and operated by Great Smoky Mountain Helicopters, Inc., doing business as Smoky Mountain Helicopters as a Title 14 Code of Federal Regulations (CFR) Part 91 local air tour flight. Visual meteorological conditions prevailed, and no flight plan had been filed for the flight that departed Sixty Six Heliport (6TN3), Sevierville, Tennessee, about 1600.

According to the operator, the helicopter had been purchased in 1986 for air tour/sightseeing purposes. At the time of the accident, the operator owned two helicopters, a Bell 206B that was based in Cherokee, North Carolina, and the accident helicopter, which was based at 6TN3.

A company pilot reported that he flew the helicopter on an estimated 10 local sightseeing flights on the morning of the accident. The accident pilot took over from him between 1300 and 1400 and completed 5 sightseeing flights in the helicopter before the accident flight. The company pilot reported that he checked the helicopter's fuel level before the departure of the accident flight, and the fuel level was "just below the 6-inch line," which corresponded to about 300 pounds of fuel.

The pilot of another helicopter operating in the area about the time of the accident reported that he did not hear any distress calls. He further stated that he heard the accident pilot make a normal landmark position report over "wonderworks."

A witness who lived near the accident site reported that he was outside when he observed the helicopter at a low altitude in a descent and that it "didn't sound right." He further described the sound as if "the engine was wound tight" and it "lost the rotor sound." He then heard the engine go silent, "as if the pilot cut the power," which was followed by sounds associated with impact. Another witness reported hearing the impact and seeing the accident site engulfed in fire. PERSONNEL INFORMATIONAccording to Federal Aviation Administration (FAA) airmen records, the pilot held commercial pilot and flight instructor certificates with ratings for rotorcraft-helicopter and instrument-helicopter. He reported a total flight experience of 550 hours, with 300 hours accumulated during the preceding 6 months on the application for his most recent FAA second-class medical certificate, which was issued on April 21, 2015.

According to company records, the pilot was hired in April 2015. He satisfactorily completed a factory Bell Helicopter 206L pilot transition course on April 10, 2015 and received a logbook endorsement that noted satisfactory completion of a flight review in accordance with 14 CFR section 61.56 on that date. Review of the pilot's logbook revealed that, as of March 25, 2016, he had logged about 1,310 hours of total flight experience, which included about 875 hours in Bell 206-series helicopters. According to the operator's helicopter log, the pilot flew the accident helicopter on several occasions between March 25 and the accident flight; however, the flight time that was accumulated by the pilot during these flights could not be determined. AIRCRAFT INFORMATIONThe seven-seat helicopter was manufactured in 1977 and issued an FAA standard airworthiness certificate in the normal category on March 1, 1977. It was equipped with a two-blade main rotor system and a two-blade tail rotor system that were powered by a 420-horsepower Rolls-Royce (formerly Allison) 250-C20B turboshaft engine.

Review of maintenance information revealed that, at the time of the accident, the helicopter had accumulated about 22,562 total hours, and the engine had accumulated about 8,550 total hours. The helicopter had been operated for about 40 hours since its most recent 100-hour and annual inspections, which were signed-off concurrently on March 4, 2016.

According to engine records, the engine fuel pump, model number 386500-5, serial number T103542, was manufactured by the Power Accessories Division of TRW, Inc., later known as Argo-Tech Corporation and now a part of Eaton Corporation. The fuel pump was installed on the engine on June 23, 2009, at an engine total time of 7,472.0 flight hours. A maintenance record entry stated that, at the time of installation, the fuel pump had 0 flight hours since overhaul. Based on the engine total time at the time of the accident, the fuel pump had accumulated about 1,078 flight hours since its last overhaul. According to the Rolls-Royce M250-C20 series maintenance manual, the fuel pump had an overhaul interval of 4,000 hours. Before installation on the accident engine, the fuel pump was overhauled at International Governor Services (IGS) in Broomfield, Colorado. The IGS work order stated that the pump was overhauled in accordance with Argo-Tech Component Maintenance Manual (CMM) No. 73-10-10, revision 0, dated November 2000. Signed-off inspections in the work order included dimensional checks; fluorescent penetrant inspection of the filter housing, bypass filter housing, pump cover, and gear housing assembly; and magnetic particle inspection of the main drive shaft, drive gear, and driven gear. No anomalous findings were recorded in these inspections. METEOROLOGICAL INFORMATIONThe 1615 weather observation at Gatlinburg-Pigeon Forge Airport (GKT), Sevierville, Tennessee, located about 3 nautical miles northeast of the accident site, reported wind from 220° at 10 knots, 10 statute miles visibility, clear skies, temperature 24°C, dew point 2°C, and an altimeter setting of 29.93 inches of mercury. AIRPORT INFORMATIONThe seven-seat helicopter was manufactured in 1977 and issued an FAA standard airworthiness certificate in the normal category on March 1, 1977. It was equipped with a two-blade main rotor system and a two-blade tail rotor system that were powered by a 420-horsepower Rolls-Royce (formerly Allison) 250-C20B turboshaft engine.

Review of maintenance information revealed that, at the time of the accident, the helicopter had accumulated about 22,562 total hours, and the engine had accumulated about 8,550 total hours. The helicopter had been operated for about 40 hours since its most recent 100-hour and annual inspections, which were signed-off concurrently on March 4, 2016.

According to engine records, the engine fuel pump, model number 386500-5, serial number T103542, was manufactured by the Power Accessories Division of TRW, Inc., later known as Argo-Tech Corporation and now a part of Eaton Corporation. The fuel pump was installed on the engine on June 23, 2009, at an engine total time of 7,472.0 flight hours. A maintenance record entry stated that, at the time of installation, the fuel pump had 0 flight hours since overhaul. Based on the engine total time at the time of the accident, the fuel pump had accumulated about 1,078 flight hours since its last overhaul. According to the Rolls-Royce M250-C20 series maintenance manual, the fuel pump had an overhaul interval of 4,000 hours. Before installation on the accident engine, the fuel pump was overhauled at International Governor Services (IGS) in Broomfield, Colorado. The IGS work order stated that the pump was overhauled in accordance with Argo-Tech Component Maintenance Manual (CMM) No. 73-10-10, revision 0, dated November 2000. Signed-off inspections in the work order included dimensional checks; fluorescent penetrant inspection of the filter housing, bypass filter housing, pump cover, and gear housing assembly; and magnetic particle inspection of the main drive shaft, drive gear, and driven gear. No anomalous findings were recorded in these inspections. WRECKAGE AND IMPACT INFORMATIONThe helicopter impacted trees near the top of a ridge that was about 1,100 ft mean sea level (msl). The main wreckage was found on its left side on a heading of about 340° magnetic in a wooded area near the bottom of a ridge. An initial tree strike was identified about 405 ft south of the main wreckage on top of the ridge at an elevation of about 1,100 ft mean sea level. Pieces of Plexiglas and the front-left piece of skid tube were found in the immediate vicinity of the initial tree strike. The primary debris path began at the top of the ridge and extended down to the main wreckage at the bottom of the ridge. The main wreckage was mostly consumed by a postcrash fire, and the entire area surrounding the main wreckage was charred. All major structural components of the helicopter were located at the accident site.

Airframe and Rotor Systems

The upper portion of the main fuselage with the engine and main transmission still attached was resting on its left side and exhibited crush damage. The midsection of the tail boom, including the horizontal stabilizer, was found separated but immediately aft of the main wreckage. The left horizontal stabilizer was fractured about mid-span. The outboard portion of the left horizontal stabilizer and the vertical fin were found at the top of the ridge, about 110 ft south of the main wreckage.

The cockpit instruments were observed ahead of the main fuselage along the debris path. The instruments exhibited thermal distress. The caution and warning panel (CWP) was observed behind the main fuselage along the debris path, and it also exhibited thermal distress. Subsequent X-ray examination of the CWP was conducted at the NTSB Materials Laboratory in Washington, DC, to assess the condition of the individual light bulb filaments. The examination found that several of the bulb globes were melted due to thermal exposure; all of the lights had filaments present; and all of the filaments were visible in the X-ray. Several of the filaments were broken, but none of the bulbs demonstrated hot coil filament stretching. These findings were consistent with none of the lights bei...