79-10-10 AYRES CORPORATION (FORMERLY ROCKWELL INTERNATIONAL AND SNOW AERONAUTICAL COMPANY): Amendment 39-3469. Applies to all Ayres S-2D and S-2R airplanes certificated in all categories having installed the rudder assembly with the single upper hinge (P/N 54030-87). This AD does not apply to S-2D and S-2R airplanes which have installed a rudder assembly with three upper hinges. \n\n\tCompliance is required as indicated unless already accomplished. \n\n\tTo prevent the possible separation of the single upper hinge from the rudder assembly and consequent possible loss of airplane directional control, accomplish the following: \n\n\tWithin 10 hours' time in service after the effective date of this AD, and at intervals not to exceed 100 hours' time in service and thereafter on all S-2D and S-2R airplanes having an installed rudder assembly with a single upper hinge (P/N 54030-87), perform the visual repetitive inspection in accordance with procedures listed in paragraph 1. \n\n\t1.\tInspection Procedures \n\n\t\t(a)\tRemove rudder assembly from airplane. Remove rudder as outlined in the Ayres (Thrush) Maintenance Manual, Section VII. \n\n\t\t(b)\tStrip fabric and dope from area around upper hinge to facilitate the inspection as shown in Figure 1. \n\n\t\t(c)\tInspect with 10 power magnification in and around weld bead on upper hinge for cracks as shown in Figure 1. \n\n\t\t(d)\tIf no cracks are discovered, comply with paragraph 2. If no cracks are discovered, comply with paragraph 3\n\n\n\n\n\n\n\n\t2.\tAction required if cracks are discovered \n\n\t\tIf a crack or cracks are detected in the area of the upper hinge, accomplish any one of the available options listed below: \n\n\t\t(a)\tReplace the rudder assembly having the single upper hinge (P/N 54030-87) with the rudder assembly having triple upper hinges (P/N 54030-987) prior to further flight. \n\n\t\t(b)\tModify the single upper hinge rudder assembly in accordance with Ayres Custom Kit No. CK-AG-18 prior to further flight. \n\n\t(c)Replace the cracked single upper hinge rudder assembly with an airworthy single upper hinge rudder assembly prior to further flight and continue the paragraph 1. inspection at intervals not to exceed 100 hours' time in service. \n\n\t\t(d)\tRepair the single upper hinge rudder assembly in accordance with the procedures of Advisory Circular (AC) 43.13-1A, Chapter 2, prior to further flight and continue the paragraph 1. inspection at intervals not to exceed 100 hours' time in service. \n\n\t3.\tAction required if cracks are not discovered \n\n\t\tContinue the paragraph 1. inspection at intervals not to exceed 100 hours' time in service unless options (a) or (b) of paragraph 2. are accomplished. If accomplished, the repetitive inspections may then be discontinued. \n\n\tAyres Service Bulletin SB-AG-15 also pertains to this subject. \n\n\tCompliance with the provisions of this AD may be accomplished in an equivalent manner approved by the Chief, Engineering and Manufacturing Branch, FAA, SouthernRegion. \n\n\tThis amendment is effective May 23, 1979.