What was found
AT 29,000 FT HEARD LOUD SQUEAL IN COCKPIT, ALSO CABIN DIFFERENTAL GAUGE CLOSE TO RED BAND. FLIGHT ATTENDANTS REPORTED LOUD HISS FROM 12AB AREA. NOISE QUIT WHILE DESCENDING THROUGH 18,000. SYSTEM INOP IN AUTO 2, MANUAL CONTROL WAS OK. RETURNED TO JFK. REPLACED CONTROLLER AND SELECT PANEL, SYSTEM CHECKS NORMAL.