Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all Boeing Model 747-100, 747- 100B, 747-100B SUD, 747-200B, 747-200F, 747-200C, 747-300, 747SR, and 747SP series airplanes. This proposal would require repetitive inspections for discrepancies of the structure near and common to the upper chord and splice fittings of the rear spar of the wing, and repair if necessary. This proposal also would provide for an optional modification that, if accomplished, would terminate the repetitive inspection requirement, but would necessitate eventual post- modification inspections. This action is necessary to find and fix fatigue cracking of structure near and common to the upper chord and splice fittings of the rear spar of the wing, which could result in loss of structural integrity of [[Page 36507]] the airplane. This action is intended to address the identified unsafe condition.