The Bell 427 is the subject of a new FAA airworthiness directive requiring replacement of certain tailboom attachment hardware and at certain intervals determining the torque of the attachment hardware. It was prompted by a review of the tailboom attachment installation that revealed the torque value of the bolts specified in the maintenance manual, and applied during manufacturing, was incorrect and exceeded the recommended torque range. An over-torque of the tailboom attachment bolt could result in bolt failure, loss of the tailboom and subsequent loss of control of the helicopter.