Transport Canada has issued airworthiness directive CF-2022-68 mandating torque checks and visual inspections on Bell 407 tail booms following the issuance of a similar alert service bulletin (ASB 407-22-128) on December 8 from Bell earlier this month.
The actions follow calls by the NTSB for such inspections as it continues its investigation of an in-flight tail boom separation on a 407 in Hawaii earlier this year. The 407 is manufactured in Canada and Transport Canada is the original grantor of its type certificate. The checks and inspections must be performed within 25 hours of time-in-service or 30 days, whichever comes first. The effective date is December 29.
Specifically, the AD calls for both tail boom attachment hardware torque checks and visual inspections of sealants on the aft fuselage, and replacement of any hardware that does not meet the torque check along with a repetitive torque check. It also requires the replacement of sealant that does not meet the Bell ASB, and visual inspection of tail boom attachment fittings, aft frames, aft fuselage bulkhead, the aft section of the canted web, tail boom canted bulkhead, and upper and lower tail boom longerons for cracks, dents, loose fasteners, deformation, corrosion, and general condition. Any problems found must be rectified per Bell product support engineering before further flight.