60-20-01: Wing Rivet Replacement

60-20-01 AERO COMMANDER: Amdt. 204 Part 507 Federal Register September 28, 1960. Applies to Models 680-E and 720, Serial Numbers 501, 623 Through 873 Except 820, 850, 860, 867 and 872. Compliance required within the next 100 hours' time in service after the effective date of this amendment. The manufacturer's inspection has determined a nonconformity with the approved design data and it is possible that aircraft in service may have the following nonconformity: AN 426AD-5 rivets have been installed instead of 3/16-inch huckbolts in the lower surface of the wing at the rear spar between wing station 54 and the inboard nacelle attach angle on both the left and right wings. (a) Inspection. Inspect the lower wing at rear spar between wing station 54 and the inboard nacelle attach angles on both the left and right wings to determine whether 3/16-inch huckbolts or AN 426AD-5 rivets have been installed. If the AN 426AD-5 rivets are installed, the wing shall be reworked as outlined in paragraph (b). (b) Rework. Remove flaps and wing trailing edge closeout skins on both left and right wings. Drill out the AN 426AD-5 rivets and replace with AN 426AD-6 rivets. These rivet heads will protrude below the wing surface by approximately 0.030 inch. Do not overdrive the rivets in an attempt to sink them completely. Measure the distance between the rivet which passes through the wing skin and rear spar cap at wing station 54 and the screw which passes through the inboard nacelle attach angle. This distance should be approximately 4.5 inches and should contain six rivets (0.75 inch on center) and the screw. If only five rivets exists in this area, a brazier head rivet (AN 456AD-6) must be added between the nacelle attach angle screw and the next rivet inboard. If sufficient space does not exist to permit minimum rivet to rivet spacing of three rivet diameters, contact the Service Department, Aero Design & Engineering Company for approved repairinstructions. Replace flaps and left and right wing trailing edge skins. (Aero Design Service Bulletin No. 62 covers this same subject.) This directive effective October 28, 1960.