Rouge A319 near Philadelphia on Oct 20th 2014, loud noise and acrid smell in cockpit

An Air Canada Rouge Airbus A319-100, registration C-GSJB performing flight RV-1786 from Toronto,ON (Canada) to St. George's (Grenada) with 135 people on board, was enroute at FL330 about 20nm south of Philadelphia,PA (USA) when the crew heard a loud noise followed by an acrid smell on the flight deck. The flight crew decided to turn around and return to Toronto, on the way back two more encounters of that loud noise occurred. The aircraft landed safely back in Toronto about one hour after turning around.

The Canadian TSB reported that maintenance found an Avionics Equipment Vent Control (AEVC) exhaust fan bearing was worn and grinding during operation. The fan was replaced.