AD 70-11-01

70-11-01 BOEING: Amdt. 39-992 as amended by Amendment 39-1078. Applies to Boeing Model 747-100 Series airplanes. Compliance required within the next 40 flights after the effective date of this AD on aircraft having 960 or more flights, and thereafter at intervals not to exceed 40 flights from the last inspection. To detect cracking in the wing trailing edge aft flap support arms of Boeing Model 747-100 series airplanes accomplish the following or an alternate procedure approved by the Chief, Aircraft Engineering Division, FAA Western Region. (a) Inspect the wing trailing edge aft flap support arms for cracks in accordance with Boeing Alert Service Bulletin No. 27-2024, or later FAA approved revision. (b) If no crack is found, repeat the inspection for cracks at intervals not to exceed 40 flights. (c) If crack is found: (1) and the crack length is 0.4 inches or greater, replace flap support arm with a serviceable part of the same part number in accordance with Boeing ASB 27-2024 (or later FAA approved revision) before further flight. After replacement repeat visual inspection per (b). (2) and the crack length is less than 0.4 inches, the part may be continued in service provided that no more than one cracked support arm per flap panel exists. Parts so continued in service must be inspected at intervals not to exceed 20 flights, subject to the provisions of (c)(1) above. (d) Repetitive inspections may be discontinued upon replacement of the existing aft flap support arm assemblies with new, improved support arm assemblies per Boeing Service Bulletin No. 27-7024, revision 2, or later FAA approved revision. Replacement of an existing support arm assembly with the new improved support arm assembly eliminates inspection requirement at that location only. Amendment 39-992 effective May 25, 1970. This Amendment (39-1078) becomes effective September 15, 1970.