52-24-01\tNAVION: Applies to All Models, Serial Numbers NAV-4-2 and Above. \n\nCompliance required as soon as possible but not later than November 1, 1952. \n\nIn order to eliminate the possibility of the aileron control chain jamming, each end of the fiber channel chain guard should be reworked as shown in Figure 1. The chain and guard are on the control column. \n\n(Ryan Navion Field Service Bulletin No. 18 dated September 3, 1952, covers this same subject.) \n\n\nAD 52-24-01