Accident Overview
On October 18, 2020, at approximately 1059 eastern daylight time, a Robinson Helicopter Company R22 Beta, registration N566BC, was substantially damaged when it collided with terrain near Barrow County Airport (WDR) in Winder, Georgia. The private pilot, the sole occupant, was seriously injured. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal operation.
Flight Sequence
The pilot had departed from Gwinnett County Airport (LZU) in Lawrenceville, Georgia, and flown to WDR to practice takeoffs and landings. During the fifth circuit of the traffic pattern, the pilot performed a touch-and-go landing. After takeoff, while turning onto a left crosswind leg, the pilot heard a metallic noise described as “metal against metal,” and the helicopter “jerked.” As the pilot looked for a suitable landing area, the helicopter jerked again. Suspecting a loss of power, the pilot observed the helicopter descend “straight down” through trees before impacting the ground.
Post-Accident Examination
The helicopter came to rest on its left side. Structural damage was noted to the fuselage, tailboom, main rotor, and tail rotor. The engine sustained minimal impact damage; the crankshaft could be rotated more than 360° by hand using the cooling fan, and no anomalies were observed in the engine.
Examination of the cooling fan assembly revealed that the alignment marks (torque stripes) on the fanwheel were misaligned by about 90° from the corresponding marks on the nut and by about 10° from the roll pin. The paint around the fanwheel-to-hub hardware was displaced, and surface corrosion and fretting residue were present on exposed metal. The attachment bolts were loose, with threads extending more than two threads beyond the nuts, and could be easily rotated with a wrench.
Most of the drive system vee-belts were missing; only a 2-foot section of one belt was recovered. This section lacked backing, had a jagged edge on one end and a frayed end on the other. The friction surfaces were smooth with no glazing or thermal damage.
The belt tension actuator extended 1.65 inches between the scissor mounts. The scissors were deformed, and the overtravel switch was damaged. The upper and lower actuator support bearings rotated smoothly.
The actuator was removed and functionally tested at Robinson Helicopter Company. The load tension and amperage draw were slightly above production specifications. The fuse installed in the actuator circuit protection holder was a 2-ampere fuse; specifications required a 1.5-ampere fuse. The spare fuse holder contained a 1.5-ampere fuse.
Maintenance Findings
The helicopter was not equipped with an actuator time delay assembly, as prescribed by Robinson R22 Service Bulletin SB-113A, and the maintenance records did not indicate compliance with that bulletin. The service bulletin described that the actuator fuse normally prevents overtensioning, but in some cases a vibrating switch could allow gradual overtension without blowing the fuse. The bulletin introduced a time delay to prevent actuator motor operation unless switch contacts were closed for about 1/4 second.
According to maintenance logbooks, the helicopter underwent an overhaul in 2000, about 180 hours before the accident, and a 100-hour inspection was performed about 84 hours prior. Per Robinson Helicopter Company, the fanwheel should have been replaced at the most recent overhaul, but this replacement was not documented. The fanwheel should also have been visually inspected during the 100-hour inspection and during any preflight inspection by the pilot.