N4055NRobinson Helicopter R44 · 2020

On April 22, 2021, about 2104 eastern daylight time, a Robinson Helicopter R44, N4055N, was destroyed when it was involved in an accident near Forkston, Pennsylvania. The pilot was fatally injured. The helicopter was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

According to radar track data from the Federal Aviation Administration, the pilot took off from Allentown Queen City Municipal Airport (XLL), Allentown, Pennsylvania about 2010. He contacted Allentown approach control at 2011 and requested VFR flight-following to Bradford County Airport (N27), Towanda, Pennsylvania. After departure, the helicopter proceeded to the northwest, climbing to a cruise altitude between 3,000 and 4,000 ft above mean sea level (msl), remaining closer to 3,000 ft msl for most of the flight. At 2028, Allentown approach directed the pilot to contact Wilkes-Barre (AVP) approach. The pilot checked in with AVP approach and was issued the local altimeter setting. Shortly after passing Kasson Brook, Pennsylvania, the helicopter made a slight right turn, then entered a right, descending spiral until radar contact was lost about 2104 (see figure 1). The last recorded radar location was near the accident site location. No distress calls were received from the pilot prior to the accident.

Figure 1 - Helicopter's flight track during the final moments of the flight.

The pilot’s widow was interviewed after the accident. She reported that her husband purchased the helicopter about 1 year prior to the accident. He used the helicopter to commute to work at the hospital in Sayre, Pennsylvania. She stated that he had a normal work week prior to the accident; meals and rest were also normal. The pilot departed for the hospital later than he normally would have on the night of the accident. Flying at night was not an issue for her husband.

The pilot’s 208 hours of logged flight time in helicopters were split equally between R22 and R44 models. He began his helicopter training in the R22 and transitioned to the R44 after he purchased the accident helicopter in June 2020. He obtained his rotorcraft-helicopter rating in the accident helicopter on September 19, 2020. The pilot held an instrument rating in airplanes but not in helicopters.

The helicopter was not approved for flight in instrument meteorological conditions.

The National Weather Service (NWS) Surface Analysis Chart centered over the eastern United States for 2000 depicted a trough located from northcentral Pennsylvania to southwestern Pennsylvania. There were no low- or high-pressure systems located near the accident site. The accident site was located east of the surface trough. Troughs can act as lifting mechanisms to help produce clouds and precipitation if sufficient moisture is present.

Greater Binghamton, New York Airport (BGM) was located 44 miles north of the accident site at an elevation of 1,636 ft. The 2053 observation included wind from 310° at 5 knots, 1 ½ statute miles visibility, with light snow, a broken ceiling at 4,300 ft, and overcast skies at 5,500 ft. The 2121 observation included wind from 300° at 8 knots, 1 ½ statute miles visibility, with light snow and mist, a broken ceiling at 2,900 ft, broken skies at 3,800 ft, and overcast skies at 5,000 ft.

A review of recorded Doppler radar data revealed a band of precipitation (snow showers) moving across the area of the accident site at the accident time. The NWS office in Binghamton issued an area forecast at 1953 for the area that included lake effect snow showers moving across the region. AIRMETs active at the time included mountain obscuration, moderate turbulence, and moderate icing.

The accident pilot did not request weather information from Leidos Flight Service or ForeFlight. There is no record of the pilot receiving or retrieving any other weather information before or during the accident flight.

At the accident site, sunset was 1953 and the end of civil twilight was 2023. At the time of the accident, the moon was located at an altitude of 60.66° and azimuth of 160.80° with 77.7% of the moon visible disk illuminated.

The helicopter was not approved for flight in instrument meteorological conditions.

The helicopter collided with trees and terrain in a remote, wooded area. The wreckage was recovered to a storage facility where an examination was conducted by a National Transportation Safety Board (NTSB) air safety investigator.

The aluminum and fiberglass structure of the fuselage and cabin were consumed by a postaccident fire. The forward end of the tailcone and empennage were mostly consumed by fire. The horizontal and vertical firewalls were deformed from impact and heat distress. The cyclic, collective, and antitorque pedals were fractured, deformed, and thermally damaged and were no longer attached to the structure.

The fuel tank bladders and shells were completely consumed by postaccident fire. Both filler caps were secure on their filler necks. Both finger strainers were clean and unobstructed. The fuel lines and hoses were damaged by postaccident fire. The fuel valve was found in the ON position.

The main rotor hub remained attached to the driveshaft. Both main rotor blades were cut by recovery personnel. Both blades exhibited impact damage to the leading edges and multiple fractures were observed throughout the length of the blades. The tail rotor blades sustained impact and thermal damage.

Most of the flight control tubes in the cabin and airframe areas were consumed by postaccident fire. All connections to the main rotor controls were accounted for, and all but three of the rod ends for the tail rotor controls were accounted for. The visible disconnects at the rod ends displayed either overload or thermal damage. The hydraulic servos moved smoothly by hand.

The engine separated from the airframe and exhibited heat and impact damage throughout. The engine was suspended from a lift and partially disassembled to facilitate the examination. The engine accessories were removed, and the crankshaft was rotated by turning the cooling fan. All six pistons were observed to move in their respective cylinder bores; however, the intake and exhaust valves were not observed to move as the crankshaft was rotated. Compression and suction were observed from the cylinders where both the intake and exhaust valves were closed. Observation of the crankshaft gear through the magneto mount openings in the accessory case revealed that the crankshaft gear did not rotate as the crankshaft was rotated. The head of the crankshaft gear bolt was observed raised about 1/8 inch above the crankshaft gear. The bolt safety washer was in place.

The accessory case was removed, and the crankshaft gear dowel pin was sheared, consistent with sudden stoppage of the accessory gears at impact. The crankshaft gear bolt was removed and was unbroken. The bolt head was damaged, consistent with contact with the oil pump drive. The first 3/16 inch of the bolt threads were damaged.

The crankshaft gear, crankshaft gear bolt, and safety washer were sent to the NTSB Materials Laboratory for examination. By design, the crankshaft gear contained a hole in its pilot flange that interfaced with an alignment dowel that was press-fit into a counterbored recess on the aft end of the crankshaft. The alignment dowel had fractured, and the separated piece of the dowel was captured in the pilot flange hole. All components (except the tip of the bolt) had dark-tinted surfaces, including the dowel fragment’s fracture surface, consistent with exposure to elevated temperatures. The tip of the bolt had a shiny appearance and stripped threads, consistent with damage during extraction of the bolt. All surfaces were examined for indications of burnishing, rubbing, or wear, but none were found. The dowel’s fracture surface had a flat, featureless appearance, with no apparent crack arrest marks. Shear lips were observed along the radially inward and outward edges of the fracture surface. The chamfer around the pilot flange hole exhibited deformation and metal transfer at the leading edge (the edge that leads during rotating of the crankshaft/gear assembly). The features were consistent with an overstress fracture of the dowel in shear and bending.

Postaccident examination of the airframe and engine revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation.

VFR into IMC

In April 2003, the Federal Aviation Administration (FAA) published Advisory Circular 61-134, General Aviation Controlled Flight into Terrain Awareness. The circular stated in part:

Operating in marginal VFR [visual flight rules]/IMC conditions is more commonly known as scud running. According to National Transportation Safety Board (NTSB) and FAA data, one of the leading causes of GA accidents is continued VFR flight into IMC. As defined in 14 CFR part 91, ceiling, cloud, or visibility conditions less than that specified for VFR or Special VFR is IMC and IFR [instrument flight rules] applies. However, some pilots, including some with instrument ratings, continue to fly VFR in conditions less than that specified for VFR. The result is often a CFIT [controlled flight into terrain] accident when the pilot tries to continue flying or maneuvering beneath a lowering ceiling and hits an obstacle or terrain or impacts water. The accident may or may not be a result of a loss of control before the aircraft impacts the obstacle or surface. The importance of complete weather information, understanding the significance of the weather information, and being able to correlate the pilot's skills and training, aircraft capabilities, and operating environment with an accurate forecast cannot be emphasized enough.

According to autopsy report from the Office of the Coroner, Wyoming County, Pennsylvania, the cause of death of the pilot was blunt force trauma due to helicopter crash and the manner of death was accident. The examination to identify any natural disease was limited by extensive trauma.

Toxicology testing performed by the FAA Forensic Sciences Laboratory detected ethanol in the pilot’s liver tissue at 0.048 grams per hectogram (gm/hg) and n-butanol in the pilot’s liver tissue; no other tested for drugs were detected in his muscle tissue.

Ethanol is a social drug commonly consumed by drinking beer, wine, or liquor. It acts as a central nervous system depressant; it impairs judgment, psychomotor functioning, and vigilance. Ethanol is water soluble, and after absorption it quickly and uniformly distributes throughout the body’s tissues and fluids. The distribution pattern parallels water content and blood supply of the tissue. Ethanol can be produced after death by microbial activity, sometimes in conjunction with other alcohols such as butanol. Extensive trauma increases the spread of bacteria and raises the risk of ethanol production after death.