57-09-01: Aileron Bellcrank Casting

57-09-01 AERO COMMANDER: Applies to All Model 520 Aircraft, Serial Numbers 31 and Above, and to All Models 560, 560A and 680 Aircraft. Compliance required not later than the next 3 hours of flight or May 15, 1957, whichever occurs first and at 100-hour intervals thereafter. As a result of finding cracks in the aileron bellcrank casting in the vicinity of the aileron push-pull rod attach bolt, the following action is considered necessary unless already accomplished. Inspect, using dye penetrant or fluorescent methods, all aileron bellcrank castings P/N 3510005 on bellcrank assembly P/N 4510004-401 and 402 for cracks in upper or lower lugs to which the aileron push-pull rod attaches. Remove rod to make the inspection, replace all castings found defective and reattach push-pull rod, making certain no clearance exists between casting lugs and rod-end bearing inner race before tightening bolt. Use shim washers to eliminate clearance. The 100-hour reinspection of casing P/N 3510005 may be discontinued upon installation of revised casting under development by Aero Design. (Aero Design Service Bulletin No. 41, dated April 19, 1957, provides a sketch of the part and defines the area to be inspected.) This AD covers the same inspection required by CAA telegraphic instructions dated April 25, 1957.