The Airbus 380 is here again - the fourth time in two years.

MSN 007 - one of five test A-380s flying currently - arrived at Changi Airport on Thursday afternoon, following a 12-hour-plus flight from Toulouse in France.

It is here at the request of Singapore Airlines (SIA), which will be the first to fly the double-decker jet in October.

The trip this time round is for SIA and the Civil Aviation Authority of Singapore (CAAS) to do a series of detailed ground tests which include passenger boarding and disembarkation; as well as loading and unloading of baggage and cargo.

The test aircraft is fully fitted with more than 500 seats in a three-class configuration.

For the first time, the facilities and infrastructure at Terminal 3, which opens on Jan 9, will also be put through their paces.

SIA spokesman Stephen Forshaw told The Straits Times that doing the tests prior to the actual delivery in October will allow the airline to put the aircraft into service as soon as possible.

The A-380 is already about two years behind schedule because of production problems.

Mr Forshaw said: 'Normally, with a new aircraft type as different as the A-380, we might require a month or even longer to train operations staff and familiarise them with the aircraft.'

Doing the ground tests in advance means the new plane can start flying 'within a couple of weeks of delivery'.

SIA, which has ordered 19 of the superjumbos, has not revealed the configuration of its A-380 but there will be fewer than 480 seats in a three-class configuration.

The aircraft will be put into service first on the Sydney route, and later on the London and Tokyo routes.

The CAAS has put in $60 million into making sure Changi is A380-ready. Taxiways have been widened along some stretches by up to 6m to accommodate the A-380's larger turning radius and there are also new aerobridges that can take passengers on and off the upper deck of the aircraft.

The A-380 was last here in November last year, as part of a critical 150-hour test flight that spanned more than 15 days.

So far, 14 airlines have ordered 165 of the superjumbos.