A proposed AD would mandate replacing the pitot probes on nearly 160 U.S.-registered Hawker 800XPs because of reports that they have frozen above FL290, causing erroneous airspeed indications. New probes and their installation would cost about $14,500 per airplane, according to the FAA. Replacement would be required at the next 24-month inspection after the compliance date of the directive. Comments on the proposal are due by November 28. For more information, contact the FAA at (316) 946-4154.