55-11-02: Thermal Relief Valves

55-11-02 PIPER: Applies to Model PA-23 Serial Numbers 23-1 to 23-142 Inclusive, 23- 144 to 23-162 Inclusive, 23-164 to 23-173 Inclusive, 23-175 to 23-177 Inclusive, 23-179 to 23- 183 Inclusive, and 23-186. Compliance required by August 1, 1955. In order to eliminate excessive pressures in the hydraulic system due to thermal expansion which can result in failure of the hydraulic actuating cylinders, it will be necessary to install thermal relief valves in the landing gear retraction line, landing gear extension line and the flap retraction line. These relief valves are to be installed in accordance with the sketch and instructions contained in Piper Thermal Relief Valve Kit 754 095. (Piper Service Bulletin No. 136 dated April 26, 1955, covers this same subject.)