Rudders installed on the affected aircraft may have a rudder post manufactured from American Iron and Steel Institute (AISI) 1025 carbon steel. Over time, rudder posts manufactured from 1025 steel are prone to fatigue failure, which could lead to loss of control of the aircraft.
If it cannot be confirmed that the rudder post is made of 4130N steel, this service bulletin mandates the replacement of the rudder with one that is known to contain a rudder post made from 4130N steel.
This Service Bulletin in referenced in AD 2025-02-11.
Download PDF of complete Service Bulletin below.
