COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Twin Commander (Gulfstream/Rockwell/ Aerocommander 500, 600 and 700) Series Aeroplanes AD/AC/66 Amdt 8 Wing Fatigue Life Limitation 13/89 Applicability: As specified in the Requirement. Requirement: Retire wing main spar lower cap assembly from service (or modify in accordance with a scheme approved by the Authority) in accordance with the schedule below: AIRCRAFT MODELS AFFECTED (The straps referred to are wing spar lower cap fatigue life improvement reinforcements) SPAR CAP RETIREMENT LIFE (Hours' Time in Service) MTOW of 6750 lb. MTOW of 7400 lb. 500B 30400 - 500B used in low level survey type operations 19900 - 500U with external strap (Pre S/N 1731) 23200 17700 500U with external strap (Pre S/N 1731) and used in low level survey type operations 15900 12100 560F 24100 560F used in low level survey type operations 16300 MTOW of 8000 lb. MTOW of 8500 lb. 680F 17100 - 680FL with external strap (Pre S/N 1731) 17100 11200 680FL with internal strap (S/N 1731 and on) 3900 30000 680FL (P) with external strap (Pre S/N 1731) - 25200 680T 27100 680V, 680W (Pre S/N 1731) with external strap 23500 685 20700 690, 690A 12900 690B 11500 690C, 695 - canted aerodynamic wing tips 11300 690C, 695 - plain tips for total operational life 24800 695A To be Advised. Note 1: If Models 680F(P) or 680FL(P) aircraft are flown predominantly at low or zero cabin differential pressure, then the retirement life of Models 680F or 680FL respectively, shall apply. COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Note 2: Should models other than the 500B, 500U and 560F be used in low level survey type operations, the Authority must be advised as a reduction in life will be necessary. For all aircraft engaged in low level operations appropriate log book entries must be made listing times actually engaged in such operations. The Authority must also be advised of any aircraft operating consistently at a flight duration of less than 45 minutes when averaged over the life of the aircraft. Note 3: The wing spar lower cap assembly subject to retirement consists of the spar cap "T" section element together with the nesting angles, outer wing spar cap splice angles and, as fitted, either internal or external reinforcement straps. The outer wing spar caps need not be retired. Note 4: On the basis of currently available fatigue substantiating data only one spar cap assembly replacement is permitted without further evaluation. This will normally allow only a single life extension from spar cap replacement or reinforcement/modification. Note 5: Models not listed in the schedule generally have fatigue lives greater than 30000 hours and are thus unlikely to be affected. Compliance: As specified in the Requirement. Background: The retirement lives of this Directive are based directly on data provided by the manufacturer. Amendment 7 was raised to clarify the strap configuration for those models which were fitted with any one of a number of strap configurations during their production life. For all models, the internal straps were fitted to S/N 1731 and subsequent. Amendment 8 corrects some typographical errors.