AD/JBK 117/26 - Tail Rotor Transmission Attachment Nuts

Requires operators of Kawasaki BK117 helicopters to inspect the four tail-rotor transmission attachment nuts for cracks per Kawasaki Service Bulletin KSB-117-291 (or later JCAB-approved revisions), replace all nuts if any are cracked, and inspect newly installed nuts, replacing them if cracked. Compliance is required before further flight. It matters because cracked attachment nuts can cause loss of tail-rotor control; operators bear the inspection, replacement and scheduling costs.