Cracked - Vertical Stabilizer Spar Web &Rudder Attachment Bolt
During a scheduled inspection, a 10X visual magnification revealed a crack located under the radius of the National Aircraft Standard (NAS) 147-29 bolt head. Removal of the bolt revealed no crack, however, closer examination revealed the bolt washer was incorrect and was not chamfered as required for NAS bolts. The Illustrated Parts Catalogue (IPC) is in the process of being revised to reflect the correct washer.
In addition, a 2” vertical crack was found in the upper end of the spar web near the upper hinge fitting. Both the upper fitting and the hinge pin were loose. The crack in the spar was not readily visible until the rudder was removed.
Transport Canada Comments:
Viking is in the process of examining the spar web to determine the root cause of the crack on the spar web. Additionally, the OEM will carry out an IPC change to add the correct P/N MS2002 washer to install under NAS 147-29 bolt head.
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