Airworthiness Directives; Boeing Model 737-600 Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 737-600 series airplanes. This action requires revising the Airplane Flight Manual (AFM) to prohibit operation of the airplane under certain conditions; repetitive inspections of the tab mast fittings of the elevator tab assemblies to detect cracking; an elevator tab freeplay check; and corrective actions, if necessary. This AD also requires installing an additional fastener on the elevator tab mast fitting, which terminates the AFM revision and extends certain repetitive inspections. This AD also requires replacement of the elevator tab mast fitting with a new, improved fitting, which constitutes terminating action for the requirements of this AD. This amendment is prompted by a report of a severe vibration incident on a Boeing Model 737-800 series airplane; inspection revealed fracturing of the elevator tab mast fitting and excessive freeplay in the elevator tab. The actions specified in this AD are intended to prevent loss of controllability of the airplane due to excessive freeplay in the elevator tab or a free tab.