Summary
We propose to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 747-200B, -200C, -200F, -300, and 747SR series airplanes. This proposed AD was prompted by reports of cracks of both lower chords and web on certain outboard struts. This proposed AD would require repetitive inspections for cracking of the lower spar chords and web, web lower spar chord modification, which includes inspections for cracking of the lower spar chords, and repetitive post modification inspections for cracking of the lower spar web and chord; and applicable corrective actions. We are proposing this AD to prevent cracked chords and web on certain outboard struts, which, if the chord severs, could result in reduced structural integrity of the diagonal brace load path and of the strut-to-wing attachment, and consequent separation of a strut and engine from the airplane during flight.