TSB IMAGE
The accident investigation revealed that evidence of blade skin debonding likely was detectable before takeoff but went unchecked despite a 2015 airworthiness directive that required preflight inspection of the specific main rotor blades installed in the accident helicopter and other R22s and R44s of similar vintage.
certified technician; and replacement of the blades with those possessing an improved design (in this case, part number C016-7) no later than Jan. 1, 2020. Compliance was also mandatory under Canadian regulations. Closer examination of blade B found exposed metal along the spar–lower skin joint near the point the blade fractured, about 38 in. from its tip, with “signs of debonding and gaps in the skin at the spar bonding joint.” The TSB noted that it was “highly likely that the metal surfaces in these areas were visible and detect- able before takeoff.” Destructive inspection also found a total of about 20 in. in which the adhesive on the spar and honeycomb didn’t show the usual imprints left by contact between them, evidence of a manufacturing defect. The TSB concluded that progressive debonding during the accident flight, compounded by the gap between a length of the spar and the honeycomb, led the blade to lose its stiffness and deform, causing pro- gressively intensifying vibrations. Because the engine showed no sign of having been on at the moment of impact, the pilot is believed to have shut it down in an attempt to control the vibrations, then stalled the main rotor attempting an autorotation. The helicopter’s maintenance logs recorded the
100-hour blade inspections but didn’t document the daily visual checks required by the AD, leaving doubt they were ever performed. This wasn’t the only shortcut revealed by the investigation. The private pilot held a helicopter rating, but his
medical certificate had expired the previous October. Further, the lack of a flight plan or flight itinerary delayed initiation of search-and-rescue efforts by a full day and vastly expanded the search area, perhaps preventing help from reaching the passenger in time to save the individual. The arming switch on the body of the ELT was found in the “off” position. The safety lock to prevent its inadvertent movement from “arm” to “off” had snapped off long enough ago that the broken edge had worn smooth.
The Takeaway
While aerodynamics is a science, operating a flying machine requires a degree of faith. Without confidence that a rapidly moving collection of parts will continue moving together in flight, climbing into the cockpit would feel suicidal. But without self-discipline, confidence can breed complacency that slips into carelessness. No one takes off expecting to crash, but thoughtful action to pre- vent that contingency—such as careful fuel planning, informed weather evaluation, and a meticulous preflight inspection—is essential to preventing accidents. Efforts to mitigate the risk of an accident are best
backed up by measures to mitigate an emergency if one occurs. When flying over remote terrain, facilitating potential search-and-rescue efforts should never be far from mind.
Filing (and opening!) a flight plan, verifying ELT opera- tion, and carrying a satellite-based tracking device can prove to be lifesaving precautions.
JUNE 2021 ROTOR 65
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