71-17-07 AEROSTAR: Amdt. 39-1269. Applies to Models 600 and 601 airplanes, Serial Numbers 60-001 through 60-0056 and 61-0001 through 61-0070 with Aerostar Kit No. 600-23-1 installed in accordance with AD 70-23-04. \n\n\tCompliance required as indicated unless already accomplished. To prevent failure of the inboard wing flap attachment ribs accomplish the following before further flight using flaps and within the next 10 hours time in service after the effective date of this AD. \n\n\ta.\tInspect for cracks in the cutout radius of the inboard wing fairing ribs (P/N A200094) in the area shown on the attached drawing. Cracked parts should be replaced with new parts using procedures shown in Aerostar Service Bulletin 600-23 or by an equivalent method approved by the Chief, Engineering and Manufacturing Branch, Southwest Region, FAA, Fort Worth, Texas. \n\n\n\n\nAD 71-17-07 \n\n\n\tb.\tInspect for missing or incorrectly located rivets attaching the inboard flap tracks to the wing fairingribs as shown on the attached drawing No. A200094. The installation should be corrected where necessary to conform to this drawing or by an equivalent method approved by the Chief, Engineering and Manufacturing Branch, Southwest Region, FAA, Fort Worth, Texas. \n\n\tThis amendment becomes effective to all known owners of Aerostar Models 600 and 601 airplanes upon receipt of individual copies mailed August 13, 1971, and to all other persons on August 23, 1971.