SYDNEY, Australia — A Qantas Airways flight between two Australian cities was canceled Friday after fumes were detected on board, while passengers on another Qantas flight found themselves stranded overnight because of damage to their plane’s wing.

The problems are the latest in a string of mechanical issues to plague the Australian airline in recent months, including a loss of hydraulic fuel that led to an emergency landing, failure of landing gear, and detached panels.

The most serious incident happened in July when a Qantas flight from London to Melbourne was forced to make an emergency landing in the Philippines after an oxygen tank exploded on board, ripping a gaping hole in the fuselage.

On Friday morning, fumes were detected during engine start-up on a Boeing 767 scheduled to fly from Melbourne to Sydney, Qantas spokesman Joe Aston said. The flight was canceled, and the plane taken out of service while engineers tried to determine what went wrong.

The 220 passengers were rebooked on later flights, Aston said.

Meanwhile, 308 passengers on a flight from Melbourne to London that was scheduled to leave Thursday spent the night waiting at Melbourne’s airport after officials realized an access panel on the wing was damaged. Qantas didn’t book passengers in a hotel overnight because officials thought the problem would be fixed promptly, Aston said.

The Boeing 747-400 finally departed Friday morning.

In August, Qantas temporarily pulled six planes from service because of irregularities in maintenance records. Qantas said it was a record-keeping issue and there were no safety implications for the aircraft.

Qantas — Australia’s largest airline — has been on the defensive since the emergency landing in the Philippines. Although no one was injured, questions were raised about the safety of the airline, which has never lost a jet aircraft because of an accident.

Earlier this week, Australia’s aviation agency said a review of Qantas found deficiencies in the way the airline maintains its planes. The Civil Aviation Safety Authority ordered Qantas to make improvements but noted the review had found no link among the airline’s recent problems.

Qantas was forced to defend itself again this week, after Britain’s advertising watchdog began investigating the company’s promotions in the U.K. that claim Qantas is the “world’s most experienced airline.”

The U.K.’s Advertising Standards Authority said it received several complaints about the ads. Some viewers called the promotions misleading because they believed other airlines were established before Qantas.

In a statement, Qantas executive general manager John Borghetti said the airline stood by the ads.

“We’re defending our assertion that Qantas is the world’s most experienced airline,” he said. “Not only has Qantas been in full operation longer than any other airline in the world, but the depth and breadth of our experience as a long-haul carrier back this up.”