47-36-01 DOUGLAS: (Was Mandatory Note 1 of AD-3L-1.) Applies to A-26B and A-26C Aircraft. \n\n\tCompliance required prior to November 15, 1947, on all serial numbers. \n\n\tTo reduce the possibility of failure of the wing bulkhead assemblies and subsequent loss of the ailerons: \n\n\t1.\tMachine face of boss on fitting assemblies P/N 4154028 and 4154028-1, to 0.335 inch, and ream bore to 0.9007 + 0.0000, -0.0005 inch. (See Figure 1.) Replace bearing AN 209K4A with self-aligning bearing, P/N AN 200KS4 and stake in six places each side. Install reworked fitting assemblies, P/N 4154028 and 4154028-1, on original bulkheads as follows: \n\n\n\t\t\n\n\t\t(a)\tOn installations using two screws, P/N 1029421-416-11, or two bolts, P/N AN 4-6A, and three rivets, enlarge the rivet holes in the fitting and bulkhead to 0.191-inch diameter and countersink the holes in bulkhead 100 degrees. Install fitting using two screws, P/N 1029421-416-11 or NAS 214-11, or two bolts, P/N AN4-6A, originally installed, two washers, P/N AN 960D416, and two nuts, AN 365-428, in the top and bottom holes, and three screws, P/N S-1029421-10-12, three washers, P/N AN 960D10, and three nuts, P/N AN 365-1032, in the three remaining holes. \n\n\t\t(b)\tOn installations using four or five screws, P/N S-1029421-10-12, reinstall fitting assemblies with original screws, washers, and nuts. \n\n\t2.\tInspect bulkhead assemblies, P/N 5153663 and 5153663-1, for cracks. If cracks are found, replace bulkhead as follows: \n\n\t\tRemove damaged bulkhead by drilling out the attaching rivets. Using damaged bulkhead as a pattern, fabricate a new bulkhead from 0.081-inch 24SO aluminum alloy sheet, condition A, annealed (Spec. No. QQ-A-362 or AN A-13.) After forming new bulkhead, heat- treat in accordance with AN 01-1A-1, section V, then apply one coat of zinc chromed primer. \n\n\t\tHold new bulkhead in place on the airplane and check for proper alignment between the upper and lower surfaces of the wing and wing tip. (Drill holes to match existing holes in the angle, skin, and fitting.) Install bulkhead using rivets, P/N AN 426AD-(0), length and diameter as required. \n\n\t\tInstall reworked fitting assemblies on new bulkheads as follows: \n\n\t\t(a)\tFor fitting assemblies which incorporate two 1/4-inch bolt holes and three rivet holes, enlarge the rivet holes to 0.191-inch diameter. Drill corresponding holes in bulkhead and countersink 100 degrees. Install fitting assembly using two screws, P/N 1029421-416-11 or NAS214-11, two washers, P/N AN 960D416, two nuts, P/N AN 365-428, three screws, P/N S- 1029421-10-12, three washers, P/N AN 960-D10, and three nuts, P/N AN 365-1032. \n\n\t\t(b)\tFor fitting assemblies which incorporate four 0.191-inch diameter holes, drill corresponding holes in new bulkhead and countersink 100 degrees. Install fitting assembly using four screws, P/N S-1029421-10-12, four washers, P/N AN 960D10, and four nuts, P/N AN 365- 1032. \n\n\tReinstall aileron and check alignment of fitting assembly. Install washers, P/N AN 960D416 or AN 960A416L, or shim stock, as required, to take up the end play between the bearing inner race and bracket assembly, aileron hinge support. \n\n\t(Army Technical Order 01-40AT-40 covers this same subject.)