Action
Supplemental notice of proposed rulemaking (NPRM); reopening of comment period.
Summary
The FAA is revising an earlier NPRM for an airworthiness directive (AD) that applies to all Boeing Model 737-600, -700, -700C, - 800, and -900 series airplanes. The original NPRM would have superseded an existing AD that currently requires reviewing the airplane maintenance records to determine whether an engine has been removed from the airplane since the airplane was manufactured. For airplanes on which an engine has been removed, the existing AD also requires an inspection of the aft engine mount to determine if the center link assembly is correctly installed, and follow-on actions if necessary. The original NPRM proposed to require the same actions for airplanes on which the engine has not been previously removed. The original NPRM resulted from reports indicating that operators found that the center link assembly for the aft engine mount was reversed on several airplanes that had not had an engine removed since delivery. This new action revises the original NPRM by expanding the applicability to include Model 737-900ER airplanes. We are proposing this supplemental NPRM to prevent increased structural loads on the aft engine mount, which could result in failure of the aft engine mount and consequent separation of the engine from the airplane.