Airworthiness Directives; The Boeing Company Airplanes

Résumé

We are revising an earlier supplemental notice of proposed rulemaking (SNPRM) for all The Boeing Company Model 737-600, -700, - 700C, -800, -900 and -900ER series airplanes. The SNPRM proposed to require inspecting for a serial number that starts with the letters "SAIC" on the left- and right-side horizontal stabilizer identification plate; inspecting for correct bolt protrusion and chamfer of the termination fitting bolts of the horizontal stabilizer rear spar, if necessary; inspecting to determine if certain bolts are installed, if necessary; and doing related investigative and corrective actions if necessary. The SNPRM was prompted by reports of incorrectly installed bolts common to the rear spar termination fitting on the horizontal stabilizer. This action revises the SNPRM by revising the applicable thresholds from flight cycles on the airplane to flight cycles accumulated on the affected horizontal stabilizer. We are proposing this SNPRM to prevent loss of structural integrity of the horizontal stabilizer attachment and loss of control of the airplane. Since these actions impose an additional burden over that proposed in the earlier SNPRM, we are reopening the comment period