...Observed The Helicopter In A Nose Down Attitude Of Nearly 90°

Location: Cornwall, NY Accident Number: ERA22FA010
Date & Time: October 10, 2021, 13:57 Local Registration: N637HP
Aircraft: Robinson Helicopter Company R44 II Injuries: 1 Fatal
Flight Conducted Under: Part 91: General aviation - Personal

On October 10, 2021, at 1357 eastern daylight time, a Robinson R44 II, N637HP, was destroyed when it was involved in an accident in Cornwall, New York. The pilot was fatally injured. The helicopter was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

According to fueling records, the pilot purchased 24.6 gallons of fuel prior to his departure from Floyd Bennet Memorial Airport (GFL), Glenn Falls, New York, about 1247. The destination was MacArthur Airport (ISP), Ronkonkoma, New York, where the helicopter was based.

According to Federal Aviation Administration (FAA) preliminary tracking data, at 1356, as the helicopter was flying southbound over the center of the Hudson River at an altitude of about 1,700 ft mean sea level (msl) it began a climbing right turn toward the west bank of the river. As it reached the shoreline, it turned right again and flew toward the northwest for about 1/4 mile, before it descended and turned left about 90°. The recorded data ended about 120 yards north of the accident site. The entire flight was about 70 minutes and the accident site was located about 120 nautical miles south of GFL. A witness located on a hiking trail about 0.1 mile southeast of the accident site reported hearing the helicopter’s engine “falter and die.” One to two seconds later, he heard a swishing sound, which he attributed to the helicopter “spinning” or being “out of control,” however he could not see the helicopter due to the tree canopy. Shortly thereafter, he heard a series of loud noises that he described as “backfires, at machine gun speed” for about 2 seconds, which he surmised was “the engine catching and the rotors slapping,” and then the sounds stopped. He reported that the visibility was “clear,” the clouds were higher than the mountain peaks, there was no fog over the river, and he could see the river clearly from his location on the hiking trail.

A second witness located about 1/2-mile northwest of the accident site reported hearing a “loud noise” that he believed was the helicopter’s engine. When he turned toward the noise, he observed the helicopter in a nose down attitude of nearly 90°, travelling at a “high speed…straight down.” The witness lost sight of the helicopter as it descended below a tree line; shortly thereafter he “heard it crash.”

Examination of the accident scene revealed a debris path that was about 150 ft long and oriented on a heading of about 188° magnetic. It began with damaged treetops and broken limbs, where the tail rotor assembly and fragments of the tail rotor guard were located. The main impact crater, which contained fragmented landing gear components was about 60 ft from the initial tree strike, with the main wreckage located about 60 ft beyond the impact crater. The fuselage was fragmented and compressed from the nose toward the rear seats. All flight control attachment fittings remained attached at their ends. The push-pull tubes between the servos and the swashplate remained intact. All other flight control push-pull tubes were fractured, some in multiple locations, consistent with overload. The sprag clutch operated normally and smoothly when rotated by hand. All four main drive belts were intact and found in place around both drive sheaves. The upper drive sheave had impact marks on the front and rear faces adjacent to the clutch centering strut and fuselage frame tubes, respectively. A 3-inch imprint consistent with the starter ring gear was present in the grooves of the upper sheave. The main and auxiliary fuel tanks were impact damaged; their bladders were breached, and a trace amount of fuel remained in the bladders.

Some vegetation surrounding the impact crater and the main wreckage showed evidence of fuel blight. The engine crankshaft rotated smoothly when turned by hand at the cooling fan. Crankshaft and valvetrain continuity were confirmed as the crankshaft was rotated. The accessory case cover was fractured with some portions missing, exposing the accessory gears. Thumb suction and compression was attained on all 6 cylinders. A borescope examination of all cylinders revealed no internal damage or anomalies. Both magnetos were found separated from the engine. The left magneto was fractured in half and with the lower half not recovered. The right magneto has some impact damage to the top near the condenser but was otherwise intact. It would not produce spark on any leads when tested. The fuel servo was separated from the engine and partially fragmented. The butterfly valve was open about 75% and could not be moved by hand. The inlet screen was absent of debris and liquid with an odor consistent with aviation fuel drained out of the servo when the screen was removed. The servo regulator section was partially disassembled and no damage to the internal rubber diaphragms or other components noted.

The air filter box was separated from the engine, the filter element was clean and unobstructed. The 1345 weather conditions reported at New York Stewart International Airport (SWF), located about 7 miles northwest of the accident site at an elevation of 491 ft msl, included an overcast cloud ceiling at 1,500 ft, visibility 5 miles in mist. At the time of the accident a National Weather Service airman’s meteorological information advisory was in effect for the accident area and the intended destination, warning of possible instrument flight rules weather conditions.

The helicopter was retained for further examination.

FMI: www.ntsb.gov