Airworthiness Directives; The Boeing Company Model 737-600, -700, -700C, -800, -900, and -900ER Series Airplanes

The FAA is superseding an existing airworthiness directive (AD) that applies to all Model 737-600, -700, -700C, -800, -900, and - 900ER series airplanes. The existing AD currently requires, for certain airplanes, a one-time detailed inspection of the inboard and outboard aft attach lugs of the left and right elevator tab control mechanisms for discrepancies, and replacement of any discrepant elevator tab control mechanism. For certain other airplanes, the existing AD requires that the inspections be done repetitively. Replacing the elevator tab control mechanism with a new Boeing-built mechanism terminates the repetitive inspections in the existing AD. This new AD requires that modified repetitive inspections be done on all airplanes, regardless of accomplishment of the terminating action specified in the existing AD. This AD results from reports of failure of the aft attach lugs on the elevator tab control mechanisms, which resulted in severe elevator vibration. This AD also results from reports of gaps in elevator tab control mechanisms and analysis that additional elevator tab control mechanisms might have bearings that will come loose. We are issuing this AD to detect and correct discrepancies in the aft attach lugs of the elevator tab control mechanism, which could result in elevator and tab vibration. Consequent structural failure of the elevator or horizontal stabilizer could result in loss of structural integrity and aircraft control.