An Investigation By Bell Textron Canada Limited Identified 43 T/R Blades That Could Have Missing Adhesive 

An Emergency Airworthiness Directive, AD #2023-17-51, has been sent to owners and operators of Bell Textron Canada Limited Model 407 helicopters over concerns with possible issues in the aircraft's tail rotor. According to the E-AD, "This emergency AD was prompted by a report of a disbonded area in a tail rotor (T/R) blade due to missing adhesive between the upper skin and core. 

Transport Canada, which is the aviation authority for Canada, has issued Transport Canada Emergency AD CF-2023-63, dated August 17, 2023 (Transport Canada AD CF-2023-63), to correct an unsafe condition on certain serial-numbered Bell Textron Canada Limited Model 407 helicopters. Transport Canada AD CF-2023-63 states that an operator identified an abnormal sound in a T/R blade while manually rotating it. A subsequent tap inspection revealed a disbonded area that exceeds allowable limits. According to Transport Canada, an investigation by Bell Textron Canada Limited identified 43 T/R blades that could have missing adhesive between the upper skin and core that was caused during the manufacturing process. 

Accordingly, Transport Canada AD CF-2023-63 requires determining if an affected T/R blade is installed, a one-time inspection of both sides of each affected T/R blade for skin to core voids and, depending on the results, replacing the T/R blade with a serviceable T/R blade. Transport Canada AD CF-2023-63 also limits the installation of a T/R blade to a serviceable T/R blade as defined therein. 

This emergency AD is intended to detect skin to core voids that exceed allowable limits in affected T/R blades. This condition, if not addressed, could result in severe vibration, failure of the T/R blade, and subsequent loss of T/R control.

The FAA is stating that this emergency AD requires accomplishing the actions specified in Transport Canada AD CF-2023-63, described previously, as incorporated by reference, except for any differences identified as exceptions in the regulatory text of this emergency AD and except as discussed under “Differences Between this Emergency AD and the Transport Canada Emergency AD.”

FMI: https://drs.faa.gov/browse/excelExternalWindow/DRSDOCID186554222920230821221450.0001