Exactly 300 days into a 2,500-hour flight-test program, the Airbus A380 very-large airliner (VLA) is here at Asian Aerospace 2006 as the European manufacturer celebrates the maiden flight of a fourth example (S/N007). The latest aircraft flew two days ago.

Making its second visit to the island state, the display aircraft–S/N004, the second flying test specimen–is performing daily flying demonstrations similar to those seen at last year’s Paris and Dubai airshows. It wears the uniform of local carrier Singapore Airlines, which will be the double-deck VLA’s first operator.

Following scheduled delivery of the initial A380-800 in November, SIA will use the aircraft for training before it begins scheduled flights around the turn of the year. At that time, Airbus expects to have handed over a second aircraft to the airline. But SIA pilots do not have to wait a further nine months. Some crew are expected to fly the A380 here before the aircraft returns to the manufacturer’s test center in Toulouse, France, next week, according to flight-test senior vice president Fernando Alonso.

Airbus has logged more than 900 flight hours in more than 250 flights with the first three articles. A380s S/N001 and 004 are bearing the brunt of testing while the third flying example–S/N002–is currently being equipped with a representative airline cabin interior in Hamburg. S/N002 should return to flight test by the end of March (after which S/N007 will be similarly outfitted).

Alonso said that while in Hamburg, S/N007 would be used for the emergency evacuation demonstrations required for certification, perhaps in April. The test had been expected on S/N002 but now will use the later aircraft.

For formal airworthiness approval, the A380 will be equipped in an 853-passenger, high-density configuration (as opposed to the 454-seat, three-class layout with which both aircraft will resume flight testing). Certification requires all passengers to disembark the aircraft in 90 seconds using the emergency doors on one side of the aircraft only.

S/N004 has come to Singapore after only a few days back at the factory following cold weather trials at Iqaluit (the former Frobisher Bay) in northern Canada. There, the A380 was exposed to temperatures down to –40 deg F.

The tests followed four days of high-altitude work with the same aircraft from José Maria Cordova International Airport at Medellin, Colombia, in January. Further weather-related work will be carried out in mid-year when the A380 is operated in temperatures exceeding 110 degrees F, probably in North Africa.

Positioning the aircraft for the cold-temperature and high-altitude trials has given Airbus further valuable experience with long-haul operations, especially engine and pressurisation performance, Alonso told Aviation International News. This is in addition to the 24,750 miles it flew late last year as the VLA underwent airport compatibility tests in Australia and Asia, including S/N002’s first visit to Singapore. Two minor anomalies raised during that first long trip away from home were intermittent high-frequency radio reception because of an antenna-bonding fault and problems with an air-conditioning pack–neither related to long-range operational considerations, according to Alonso.

Wake Vortex Issues

Having measured the large jetliner’s wake vortices since the first flight in April, with accelerated monitoring more recently, Airbus is preparing for a series of trials to better understand vortex behavior, especially the implications for following aircraft when on the approach to landing. Late last year, the International Civil Aviation Organization (ICAO) recommended a sharply increased separation distance of 10 nm between A380s and all other types–regardless of weight–compared with varying four-, five-, or six-nm spacing depending upon the weight of the trailing aircraft. ICAO also proposes 15-nm cruise separation for all aircraft following A380s, compared with the current ten nautical miles.

Now Airbus wants to conduct tests using an A380, a Boeing 747-400, a Boeing 777 and an A320 (probably a short-body A318 variant) to gauge the relative behavior of each and collect data. The manufacturer acknowledges that the VLA generates stronger vortices than does the 747-400, but argues that ICAO’s rationale is not driven by scientific tests.

Also, Airbus says the 747 should not be the limit in defining a “heavy” aircraft for separation purposes. “There is no comparative data from vortex tests with other widebodies,” said Alonso.

He told AIN that Airbus has been “surprised” by the initial ICAO proposal, which confirms the manufacturer’s belief that it must work with aviation authorities to establish standards. “Airbus is confident that we can demonstrate that the [10-nmi] separation is excessive and overly conservative.” Alonso believes it should be possible to reach agreement “close to the current ‘heavy’ separation, but we need the data to establish what is safe.”