13 February 2025
The news that owners of fabric covered Piper aircraft have worried about for a while has come true: an Airworthiness Directive requiring replacement rudder posts to be fitted on many models.
The US regulator, the FAA, has issued the AD as a result of two rudder-post failures on float-equipped Super Cubs in Alaska.
In both cases, the rudder post fractured above the upper hinge and the top portion of the rudder folded over the upper tail brace wires. A FAA investigation found three other similar cases.
The AD requires replacing any rudder equipped with a rudder post made from AISI 1025 steel tube with a rudder post made from AISI 4130 steel.
Owners had lobbied for the change only to be applied to higher power aircraft, and/or ones fitted with anti-collision beacons.
Piper Aircraft had already issued Service Bulletin 1379 in December 2022 which “Piper Considers Compliance Mandatory” in the headline.
That SB said, “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.”
Aircraft models affected are:
Download the Airworthiness Directive here
