What was found
YUL - FLT 4005 - THE CREW REPORTED THAT DURING CLIMB THROUGH ICING CONDITIONS THE F/A HEARD A 'LOUD BANG' NE THE LAV AREA, THE APU WAS ALREADY SHUTDOWN AND BLEED LEAK 1-2 WAS NOTED. BLEED LEAK 1 CLEARED AFTER ABOUT 1 MIN BLEED LEAK 2 REMAINED. ENGINE NR 2 WAS SHUTDOWN PER THE QRH. THE AIRCRAFT LANDED BACK TO YUL UNDER WEIGHT AND WITHOUT FURTHER INCIDENT. MAINTENANCE REMOVED AND REPLACED THE O-RING ON GAMAH JOINT ON THE NR 2 BLEED DUCT BY THE RADIO ALTIMETER IN THE LOW AFT WING FAIRING IAW EMB145MM 36-11-09, LEAKS AND OPS CHECKS WERE GOOD. THE AIRCRAFT WAS RELEASED TO SERVICE. (M)