Inspect both wing trailing edge ribs at the centre flap actuator attach brackets, wing stations 98.385 and 100.635, for cracks in accordance with the Accomplishment Instructions section, Part A, of Fairchild Aircraft Service Bulletin (SB) 57-016, issued 25 June 1981, revised 9 December 1981.
If no cracks are found, install the reinforcement doubler, part number 27K36075-7, in accordance with the Accomplishment Instructions section, Part B of Fairchild SB 57- 016.
If any cracks are found, replace any cracked rib with a new rib assembly, part number 27-31085-1/2 or 27-31086-1/2, and install the new reinforcement doubler, part number 27K36075-7, in accordance with the Accomplishment Instructions section, Part B and Part C of Fairchild SB 57-016.