Airworthiness Directives; Boeing Model 747 Series Airplanes

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Boeing Model 747 series airplanes. This action requires inspections to detect broken sealant common to the lower horizontal clevis of the inboard and outboard strut midspar fittings and of the fasteners, and various follow-on actions. This action also requires inspections to detect cracking, corrosion, and fracturing of the lower horizontal clevis, and replacement of discrepant parts with new or serviceable parts, or repair, if necessary. This action also provides for optional terminating action for the inspections. This amendment is prompted by reports of fatigue cracking, stress corrosion cracking, and fracturing of the horizontal clevis of the inboard midspar fitting of the number three strut. The actions specified in this AD are intended to detect and correct such cracking and fracturing, which could result in drooping of the strut at the strut- to-wing interface, and consequent separation of the engine and strut from the airplane.