Board Cites Risk of Catastrophic In-Flight Failure

The National Transportation Safety Board, on Friday, 02 December 2022, issued urgent recommendations to American and Canadian aviation regulators to require both immediate and more frequent inspections of certain components of Bell’s popular, single-engine, 407 helicopters.

NTSB Chair Jennifer Homendy asserted: “With hundreds currently in service, the Bell 407 helicopter is a popular model among tour operators, police departments, air ambulance providers, and many others—which is why our finding is so urgent. We’re calling on regulators to act immediately, before there’s another accident.”

The NTSB’s identification of the urgent safety issue derived of its ongoing investigation of a 08 June 2022 accident in which the tail-boom of a Bell 407 operating in the vicinity of Kalea, Hawaii separated from the aircraft’s fuselage during an air-tour flight. Investigators located the tail-boom more than seven-hundred-feet from the helicopter’s main wreckage. The 407’s pilot and two passengers were seriously injured; three additional passengers received minor injuries—a fortuitous outcome given the aircraft came to ground on lava-covered terrain.

Post-impact examination of the helicopter wreckage revealed deficits in all four of the attachment fittings by which the 407’s tail-boom and fuselage were ostensibly mated. Two of the fittings were found to have overload fractures, a third was compromised with multiple fatigue fractures. The upper left fitting was missing its attachment hardware altogether. An exhaustive search of the accident site turned up no sign of the missing hardware.

In the report containing the urgent recommendations, the NTSB put forth it was concerned that additional Bell 407 helicopters may be operating with missing or fractured tail-boom attachment hardware. The board stated unequivocally that the potential for catastrophic failure warrants immediate and mandatory action.

The NTSB also warned that the three-hundred-hour inspection interval Bell requires for the tail-boom attachments may not detect missing or fractured hardware. The 08 June Hawaii accident occurred just 114-flight-hours after the lost helicopter’s last inspection—which revealed no anomalies.

Accordingly, the NTSB urged the FAA and Transport Canada to require Bell 407 operators to conduct immediate inspections of their machines’ tail-boom attachment hardware, and to reduce the inspection interval from three-hundred-hours to an unspecified but more conservative timeframe for purpose of increasing the likelihood of detecting fractured attachment hardware prior to the occurrence of catastrophic failure.

The NTSB further petitioned the aviation regulators to require Bell 407 operators to report their findings to their respective FSDOs or regulatory authorities.

FMI: www.ntsb.gov