76-04-03 CESSNA: Amendment 39-2519. Applies to the airplane models and serial numbers listed below which have ARC PA-500A actuators (Serial Numbers 6265 and below) installed as part of Cessna Model 300, 400 and 400A autopilots, 300, 400 or 800 IFCS, or in Type G-830A yaw damper systems. \n\n\nMODELS\nSERIAL NUMBERS\n172L, M\n17259287 thru 17263458 \nF172K, L, M\nF1720780 thru F1721234 \nFR172H, J\nFR1720240 thru FR1720530 \n177B\n17701576 thru 17702123 \n177RG\t\n177RG0001 thru 177RG0592 \nF177RG\nF177RG0001 thru F177RG0122 \n180H, J\n18052170 thru 18052500 \n182N, P\n18260460 thru 18263475 \nA185E, F\n18501815 thru 18502565 \nP206E; TP206E\nP20600626 thru P20600647 \nU206E, F; TU206E, F\nU20601447 thru U20603093 \n207, T207\n20700149 thru 20700314 \n210K, L & T210K, L\n21059200 thru 21061040 \n310Q, T310Q\n310Q0001 thru 310Q1160 \n310R, T310R\n310R0001 thru 310R0330 \n337E, F, G; T337E, F\n33701290 thru 33701673 \nF337E, F, G\nF3370020 thru F3370071 \nT337G\t\nP3370001 thru P3370225 \nF337GP\nFP3370001 thru FP3370015\n340\n3400001 thru 3400555\n401B\n401B0001 thru 401B0221 \n402B\n402B0001 thru 402B0935 \n414\n4140001 thru 4140655 \n421B\t\n421B0001 thru 421B0970 \n\n\tCompliance: Required as indicated, unless already accomplished. \n\n\tTo preclude restrictions of control movement due to jamming of the ARC PA-500A actuator gear train, accomplish the following: \n\n\tA)\tUntil Paragraph B is accomplished, within 100 hours' time in service after the effective date of this AD and thereafter at intervals not to exceed 100 hours' time in service, inspect the ARC PA-500A actuator(s) in accordance with Cessna Service letter AV75-10, dated December 19, 1975, or later approved revisions, which service letter incorporates ARC Field Engineering Service Bulletin No. 181. Correct any unsafe condition noted by adjustment replacement of parts as necessary. \n\n\tB)\tWithin twelve months of the effective date of this AD, modify the ARC Model PA-500A actuator(s) in accordance with Cessna Service Letter No. AV75-10 dated December 19, 1975, or later approved revisions, which service letter incorporation ARC Field Engineering Service Bulletin No. 181. \n\n\tC)\tAny alternate method of compliance with this AD must be approved by the Chief, Engineering and Manufacturing Branch, FAA, Central Region. \n\n\tThis amendment becomes effective February 26, 1976.