Airworthiness Directives; Boeing Model 707 and 720 Series Airplanes

This amendment supersedes two existing airworthiness directives (AD), applicable to all Boeing Model 707 and 720 series airplanes, that currently require inspections of the upper chords of the wing front and rear spars, repair, if necessary, and application of corrosion inhibitor to the inspected areas. This amendment requires repetitive inspections of the upper and lower chords on the wing front and rear spars, repair, if necessary, and application of corrosion inhibitor to the inspected areas. These actions are necessary to find and fix stress corrosion cracking of the upper and lower chords on the wing front and rear spars, which could result in reduced structural integrity of the wing. This action is intended to address the identified unsafe condition.