The FAA has issued a final rule on an airworthiness directive for the Eurocopter EC 120B. It requires modifying the pilot cyclic control friction device by replacing a specified thrust washer with two thrust washers. The AD is prompted by an incident in which the pilot encountered a sudden restriction of the cyclic control movement during flight. The actions specified by this AD are intended to prevent jamming of a pilot cyclic control stick and subsequent loss of control of the helicopter.