The British Airways order is the first for the type of engine since the Qantas emergency, and is considered a sign of confidence in Rolls-Royce by a long-term client. Earlier, Rolls-Royce said the midair explosion, which forced the pilot to make an emergency landing and Qantas to ground part of its fleet, would hurt its full-year profit.

“This order does provide a much needed boost of confidence,” Howard Wheeldon, senior strategist at BGC Brokers in London, said. “Engine problems can and do occur. They have resolved it even though they could have handled it a bit better. We’ve moved on.”

The order, which had been under negotiations since September 2007, is worth more than $5 billion and includes Trent 900 engines for 12 A380 aircraft to be delivered from 2013 and Trent 1000 engines for 24 Boeing 787 Dreamliners. The contract includes options to buy another 25 engines along with a care-and-support arrangement.

“We are pleased that British Airways continues to put trust in our world-class Trent engine technology and service provision,” Rolls-Royce’s chief executive, John Rose, said in a statement.

The engine explosion on the Qantas flight did not slow or otherwise affect the contract negotiations, a representative for British Airways said. The chief executive of British Airways, Willie Walsh, said the airline had “had a long and positive relationship with Rolls-Royce and we look forward to continuing to work with them in the future.”

An investigation by Rolls-Royce, the world’s second-biggest aircraft engine maker after General Electric, concluded that a “specific component in the turbine area” of the engine had caused an oil fire and led to the problems. Rolls-Royce also said that the issue was specific to the Trent 900 model and that it would replace the module in question as part of a planned inspection of all such engines.

Qantas has reserved the option to file legal action against Rolls-Royce for the grounding of its A380 fleet after Australian regulators recommended additional safety checks. The airline said in December that it would consider legal steps in case a compensation offer from Rolls-Royce was unsatisfactory.