Reports of nuisance stall warnings triggered by frozen angle-of-attack (AOA) vanes has led FAA to mandate replacement of the parts on Boeing 757s, 767s and 727s. FAA, in a notice of proposed rulemaking set for publication July 9, is proposing a 36-month window for replacing affected AOA vanes—a shorter time period than Boeing recommended in alert service bulletins that target each model. Boeing issued the bulletins in the last six months.