Airline spokeswoman Michelle Mohr said no passengers were on board the plane at the time of the fire, KTVK-TV, Phoenix, reported.
Phoenix Fire Department officials said the fire started in the rear of the plane and it was quickly extinguished with foam. Mohr said an auxiliary power unit, in the plane's tail is believed to have been the source of the fire and a reported fuel leak.
"A preliminary inspection showed that there is no real damage to the aircraft, but it will remain out of service for a full inspection," Mohr said.
The Airbus A320 that can carry 150 passengers was to be used for Flight 504 from Phoenix to Vancouver, British Columbia, Canada, Monday night, she said.