NTSB issues urgent recommendations for inspections of Bell 407 helicopters

The National Transportation Safety Board (NTSB) urges American and Canadian aviation regulators to complete immediate and more frequent inspections of certain components on Bell 407 helicopters.

The NTSB identify the urgent safety issue during its ongoing investigation of a Bell 407 crash in Hawaii earlier this year, in which the tail boom separated from the fuselage during an air tour flight.

In that accident, investigators located the tail boom more than 700 feet from the rest of the helicopter, which crashed in lava-covered terrain.

An examination of the helicopter wreckage revealed that the upper left attachment hardware, installed in one of four fittings that attaches the tail boom to the fuselage, was missing and could not be located at the accident site. The remaining three fittings and hardware were found with the tail boom, one fitting with multiple fatigue fractures and two fittings with overload fractures.

The report containing the urgent recommendations stated that the NTSB was “concerned that there may be additional Bell 407 helicopters with missing or fractured tail boom attachment hardware, and the potential for catastrophic failure warrants immediate and mandatory action.”

Chair of the NTSB Jennifer Homendy said: “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 Federal Aviation Administration and Transport Canada have been urged to require Bell 407 operators to conduct an immediate inspective of tail boom attachment hardware and to reduce the inspection interval from 300 hours to a more conservative number to “increase the likelihood of detecting fractured attachment hardware before a catastrophic failure can occur.”

The Maine Forest Service is one of the operators of the Bell 407, unveiling the helicopter for forest firefighting and search and rescue operations earlier this year.