Summary
We propose to adopt a new airworthiness directive (AD) for all Boeing Model 737-600, -700, -700C, -800, -900 and -900ER series airplanes. This proposed AD would require repetitive testing of the rudder pedal forces or repetitive detailed inspections of the inner spring of the rudder feel and centering unit, and corrective actions if necessary. This proposed AD also requires replacement of the spring assembly in the rudder feel and centering unit, which terminates the repetitive tests or inspections. This proposed AD results from reports of low rudder pedal forces that were caused by a broken inner spring in the rudder feel and centering unit; a broken inner spring in conjunction with a broken outer spring would significantly reduce rudder pedal forces. We are proposing this AD to prevent reduced rudder pedal forces, which could result in increased potential for pilot- induced oscillations and reduce the ability of the flightcrew to maintain the safe flight and landing of the airplane.