What was found
DURING FLIGHT 2797 LT BLEED AIR LEAK LIGHT ILLUMINATED DURING TAXI. CREW RAN QRH REMAINED ON UNTIL ENGINE SHUTDOWN. A/C RETURNED TO GATE. MAINTENANCE TROUBLESHOT, INSPECTED BLEED LEAK DETECTION LOOP, INSPECTED FOR LEAKS OR CHAFES, RAN FOR 15 MINUTES, CHECKING FOR BLEED LEAKS, NONE FOUND. COULD NOT DUPLICATE PROBLEM AT ANY TIME, AS A PRECAUTION CHANGED BLEED FAULT CONTROL UNIT, RAN ANOTHER 15 MINUTES AND NO DEFECTS NOTED.