Pilots of a Sunwing Airlines Boeing 737-800 twice returned to the gate to deal with fuel spills during taxiing ahead of a service from Portugal's Faro airport.
The aircraft, bound for Katowice in Poland on 5 August, had already experienced a spill during refuelling when the right-hand main tank was overfilled.
Transportation Safety Board of Canada states that ground personnel dealt with the spill with a firefighting vehicle in attendance.
But as the aircraft (C-FTOH) taxied out for the departure, says the board, it experienced two other fuel spills.
"Each time the aircraft returned [to] the gate and the crew shut down the engines for clean-up and ground maintenance crew examination," it adds.
"Eventually the overflow stopped and the maintenance crew performed fuel balancing of the fuel tanks."
Investigators state that the jet subsequently departed Faro without further incident. None of the 180 passengers and six crew members was injured. The aircraft, built in 2009, was being sub-wet-leased at the time by the Polish division of Czech operator Smartwings.