What was found
DIVERSION - ENGINE SHUTDOWN - PILOTS REPORTED A NR 1 ENGINE DUCT LEAK LIGHT THAT ILLUMINATED AND WENT OFF 2.5 MINUTES AFTER BLEED WAS SHUT OFF. IT THEN AGAIN ILLUMINATED AND ENGINE WAS THEN SHUTDOWN AND LIGHT REMAINED ILLUMINATED. A DUCT LEAK LIGHT THEN ILLUMINATED IN FLIGHT ON NR 2 ENGINE, AS WELL AS THE APU DUCT LIGHT. MX REMOVED AND REPLACED O-RING IN THE "T" OF ENGINE DUCTING SIDE AND O-RING OF APU DUCT SIDE IAW MM 36-10-01. GROUND LEAK CHECKS WERE GOOD. PN FOR THE O-RINGS WERE M83248-1-226 AND M83248-1-228 RESPECTIVELY.