COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Fairchild (Swearingen) SA226 and SA227 Series Aeroplanes AD/SWSA226/83 Wing Trailing Edge Ribs 6/98 Applicability: Models Serial Numbers SA226-TC TC201 through TC379 SA226-T T201 through T275, and T277 through T291 SA226-T(B) T(B)276, and T(B)292 through T(B)378 SA226-AT AT001 through AT069 Requirement: 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. Note: FAA AD 98-04-05 Amdt 39-10318 refers. Compliance: Unless already accomplished, within 500 hours time in service after 21 May 1998. This airworthiness directive becomes effective on 21 May 1998. Background: Fatigue cracking of the wing trailing edge ribs has been reported. Failure of a wing trailing edge rib could result in asymmetrical flap deflection with possible loss of control of the aircraft.