Summary
We propose to adopt a new airworthiness directive (AD) for all Boeing Model 747SP series airplanes. This proposed AD would require repetitive lubrication of the rudder tab hinges and repetitive replacement of the rudder tab control rods. This proposed AD results from reports of freeplay-induced vibration of the control surfaces on Boeing Model 727, 737, 757, and 767 airplanes. We are proposing this AD to prevent damage to the control surface structure during flight, which could result in loss of control of the airplane.