Airbus has acknowledged it will require "two or three months" to obtain a realistic understanding of the A320neo's performance, following the September 25 first flight of the re-engined single-aisle twinjet. "It's not just measuring cruise and climb performance, but also engine-out behavior [and everything else] and then asking 'What does it all mean?'" commented flight and integration tests senior vice president Fernando Alonso.

The A320neo flight-test fleet will comprise eight aircraft: four A320 variants and pairs of A321 and A319 models, with half of each group powered by Pratt & Whitney PW1100G-JM geared turbofan (GTF) engines and half by CFM International Leap-1A powerplants. Airbus expects to devote some 3,000 flight hours of testing to certification of the planned six variants. The company says flight-testing will be the same for each variant, with "a plan to complete all necessary work, but the bulk will be [accomplished] on the A320, then less on the others."

Results of initial performance analysis should be available by the turn of the year, when Airbus will be preparing to introduce a second A320neo, also P&W GTF-powered, which is expected to fly in January; maiden flight of the CFM Leap-1A-engined variant is set for the middle of next year. The European manufacturer will deliver "probably all" of the A320neo test aircraft, said Alonso, who has now overseen the maiden flights of the past five Airbus projects: A320neo, A350, A318, A380 and the A400M military transport; by tradition, Airbus might retain the initial A320neo (MSN 6101).

With European certification requirements having evolved since the original A320 was developed in the 1980s, Airbus had to agree to the basis for airworthiness approval with the European Aviation Safety Agency and then present its certification plan to show compliance. The manufacturer had learned a lot about the latest requirements through flight-tests of the A380 and A350, according to Alonso. "So we knew the impact of the changes, which can involve systems, aircraft handling and so on, but this might not read across [from one aircraft design to another]," he explained.

One development, for example, has been the requirement to demonstrate aircraft handling in icing conditions. "Previously we had to expose the aircraft to severe icing conditions using [artificial] ice shapes on non-deiced parts and locations,” Alonso added. “Now, we add ice shapes on deiced areas to demonstrate [the effect of] icing when the deicing system has failed. It's all about agreeing with the authorities what we need to do because we are not starting from scratch."