Airworthiness Concern Sheet (ACS) for certain Piper aircraft: Model / Series: J-5A, J-5B, J-5C, J-5D, AE-1, HE-1, PA-12, PA-12S, PA-14, PA-16, PA-18, L-21, PA-20, and PA-22 Serial Numbers: All
Recently an accident occurred where the rudder on a PA-12 failed in flight. The airplane was a seaplane equipped with a 160 hp Lycoming O-320 engine. The original tail surfaces had been replaced with PA-18 tail surfaces in accordance with a Supplemental Type Certificate (STC). The broken upper part of the rudder post broke just above the top hinge and the upper part of the rudder folded over the tail brace wires in such a way that rudder control was severely limited and as to effectively create an additional horizontal tail, driving the tail down and the nose up. It was possible for the senior flight instructor to control the airplane in pitch, but required a lot of the available elevator deflection to do so. By dropping the water rudders, some directional control was established and the airplane was able to return to base and land, but with difficulty.