specify the mx.effects.easing.Bounce.easeOut() method to the Accordion
<?xml version="1.0"?> <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" height="550"> <mx:Script>import mx.effects.easing.*;</mx:Script> <mx:Accordion openEasingFunction="{Bounce.easeOut}" openDuration="2000"> <mx:VBox label="Pane 1" width="400" height="400" /> <mx:VBox label="Pane 2" width="400" height="400" /> </mx:Accordion> </mx:Application>