AD FAA-2012-0994

We are superseding an existing airworthiness directive (AD) for all The Boeing Company Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes. That AD currently requires repetitive inspections of the aft attach lugs of the elevator tab control mechanisms, and replacement of any discrepant elevator tab control mechanism. This new AD requires replacing the left and right elevator tab control mechanisms with elevator tab control mechanisms that have the modified attach lugs, which would terminate the existing requirements. This AD was prompted by reports of failure of the aft attach lugs on the elevator tab control mechanisms, which resulted in severe elevator vibration; and reports of gaps in elevator tab control mechanisms and analysis indicating that additional elevator tab control mechanisms might have bearings that will come loose. We are issuing this AD to prevent discrepancies in the aft attach lugs of the elevator tab control mechanism, which could result in severe elevator and tab vibration. Consequent structural failure of the elevator or horizontal stabilizer could result in loss of structural integrity and aircraft control.