Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 747-400 series airplanes. This proposal would require repetitive inspections to detect fatigue cracking of the longeron splice fittings at stringer 11 on the left and right sides at body station 2598, and various follow-on actions. This action is necessary to detect and correct fatigue cracking of the longeron splice fittings and subsequent damage to adjacent structure. Such damage could result in the inability of the structure to carry horizontal stabilizer flight loads, and consequent reduced controllability of the horizontal stabilizer. This action is intended to address the identified unsafe condition.