Action
Supplemental notice of proposed rulemaking (NPRM); reopening of comment period.
Summary
We are revising an earlier proposed airworthiness directive (AD) for all The Boeing Company Model 757 airplanes. That NPRM proposed to require a detailed inspection of the inboard and outboard main slat track downstop assemblies and a torque application to the main track downstop assembly nuts of slat numbers 1 through 10, excluding the outboard track of slats 1 and 10; a detailed inspection of all slat track housings for foreign object debris (FOD) and visible damage; and corrective actions if necessary. That NPRM was prompted by reports of fuel leaking from the front spar of the wing through the slat track housing. This action revises that NPRM by adding inspection results reporting. We are proposing this supplemental NPRM to detect and correct incorrectly installed main slat track downstop assemblies, which, when the slat is retracted, could cause a puncture in the slat track housing and lead to a fuel leak and potential fire. Since these actions impose an additional burden over that proposed in the NPRM, we are reopening the comment period to allow the public the chance to comment on these proposed changes.