Summary
We propose to supersede an existing airworthiness directive (AD) that applies to all The Boeing Company Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes. The existing 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. Since we issued that AD, Boeing has developed a modification of the aft attach lugs of the elevator tab control mechanisms, which will adequately address the unsafe condition. This proposed AD would require 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. We are proposing 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.