Singapore received its first A380 in October 2007
Singapore Airlines has grounded a second Airbus A380 super-jumbo because of a fuel pump problem.
The carrier said the move delayed passengers bound for Sydney on Monday who had to switch to smaller planes.
It added that the A380 in question was now back in service. A similar fuel pump problem grounded another of the airline's A380s back in February.
Singapore Airlines is currently the first and only carrier to enter the A380 into commercial service.
"The problem is similar to the problem which affected another aircraft a month or so back, but it is important to mention, it is not the same problem, and not the same aircraft," said Singapore Airlines spokesman Stephen Forshaw.
"The problem last time was identified to be with the electrical relay powering the pump, rather than the pump itself," he said.
Mr Forshaw added that this time the problem involved a "premature failure of the pump".
At present the airline has three of the planes, with another 16 on order.
Last week it flew an A380 into London's Heathrow Airport for the first time.
It first introduced the plane in October, on its Singapore to Sydney route.
Dubai-based Emirates will become the second airline to use the A380 when it takes its first delivery in August.
British Airways has ordered 12 of the airliners, due to be delivered from 2012, while Virgin Atlantic has ordered six, to arrive from 2013.
The airliner's wings are made at Broughton in north Wales and at Filton in Bristol. The Rolls-Royce engines that power Singapore's fleet are built at Derby.
The introduction of the A380 was delayed for more than a year due to wiring problems.