Summary
We propose to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 727 airplanes, Model 757 airplanes, and Model 767-200, -300, -300F, and -400ER series airplanes. This proposed AD was prompted by reports of nuisance stick shaker activation while the airplane accelerated to cruise speed at the top of climb. This proposed AD was also prompted by an investigation of those reports that revealed that the angle of attack (AOA) (also known as angle of airflow) sensor vanes could not prevent the build-up of ice, causing the AOA sensor vanes to become immobilized, which resulted in nuisance stick shaker activation. This proposed AD would require a general visual inspection of the AOA sensors for a part number, and replacement of affected AOA sensors. We are proposing this AD to address the unsafe condition on these products.