C-FGKZ, an Airbus 321-200 aircraft operated by Air Canada, was conducting flight ACA338 from Vancouver Intl, BC (CYVR) to Ottawa/MacDonald-Cartier Intl, ON (CYOW) with 6 crew members
and 178 passengers on board. Shortly after the departure, the landing gear failed to retract. The flight crew advised ATC, declared a Pan Pan and returned for landing at CYVR. An overweight landing was accomplished without further incident with ARFF standing by.
Subsequent maintenance actions revealed that the nose landing gear oleo had been over-serviced with hydraulic fluid. Maintenance personnel accomplished a nose landing gear service as per the
Aircraft Maintenance Manual (AMM) and the aircraft was returned to service.