Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain McDonnell Douglas Model DC-8 series -10 through -50, -61, -61F, -71, -71F airplanes, that currently requires a visual or eddy current inspection(s) of the left and right wing front spar lower caps to detect cracks migrating from attachment holes; and repair, if necessary. That AD also provided for an optional terminating modification of the front spar lower cap. This proposal is prompted by a report that additional cracking was found in the front spar lower cap of a wing. This action would require accomplishment of the previously optional terminating action. The proposed AD also would expand the applicability of the existing AD to include additional airplanes and to increase the interval for the repetitive eddy current inspections. The actions specified by the proposed AD are intended to prevent reduced structural integrity of the left or right wing due to metal fatigue failure of the front spar lower cap.