In the summer of 2011, Airbus delayed its anticipated delivery dates for two of the plane’s three versions by two years, to 2016 and 2017, to meet customers’ demands for a more powerful engine for the largest version, the A350-1000, and to focus its engineering resources better on building its top-selling version, the 314-seat A350-900, which it had promised to customers beginning in late 2013. Airbus has more than 350 orders for the A350-900, while its 270-seat model, the A350-800, has garnered 118 orders and the 350-seat A350-1000 has just 88.

Then, almost a year ago, the delivery goal for the A350-900 crept back another six months, the result of a maddening shortage of parts from third-party suppliers who were scrambling to meet demand from Airbus as Boeing gradually speeded up production of its competing 787 Dreamliner, which entered service in late 2011 and is also largely built from the same lightweight composite materials. European Aeronautic Defense & Space, Airbus’s parent, booked a €200 million charge on its 2011 third-quarter earnings due to the delay

A bug was subsequently discovered early this year in the software that drives robots responsible for drilling holes in the plane’s carbon fiber wings — which are 32 meters, or 105 feet, long — at a site in Broughton, Wales. The problem, which Airbus says it has since fixed, required that workers drill holes in the first five wings — including those for the first flight-test aircraft — by hand, adding €124 million to the A350’s development bill and pushing back the first deliveries to the second half of 2014.

Airbus said it was sticking to that timetable, with plans to begin a 12-month flight test program next summer. But analysts said they anticipated that the calendar would slip further. It is normal, they said, for snags to arise in the production and testing of new planes, especially when they use new technologies.

“Experience of recent programs shows you can get a long way into the development process before trouble shows up,” said Richard Aboulafia, an aerospace consultant at Teal Group, an analysis firm in Fairfax, Virginia. In the case of the A350’s entry into service, he said, “we have always assumed mid-2015, and we are still sticking with that.”

In addition to lessons from the painful birth of the A380, Airbus has learned much from studying Boeing’s missteps with the 787, which was three years late amid numerous problems linked to inexperience with the new composite materials, outsourcing of key elements of the plane, parts shortages and other issues.

“The 787 was rolled out as an intact aircraft before anyone figured out that things were terribly wrong,” Mr. Aboulafia said.