Summary
We propose to adopt a new airworthiness directive (AD) for certain Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes. This proposed AD would require repetitive testing of the stabilizer takeoff warning switches, and corrective actions if necessary. This proposed AD results from reports that the warning horn did not sound during the takeoff warning system test of the S132 "nose up stab takeoff warning switch.'' We are proposing this AD to detect and correct a takeoff warning system switch failure, which could reduce the ability of the flightcrew to maintain the safe flight and landing of the airplane.