Rolls-Royce said the Federal Aviation Authority (FAA) had granted a key certification to its Trent 1000 engines, which are being used to power Boeing's 787 Dreamliner jets.
The approval, called Extended Twin Engine Operations, or ETOPS, will allow the 787 to fly more than 330 minutes away from an available airfield on a single engine.
Boeing, which is already nearly three years behind on its original 787 delivery schedule, due to glitches in the supply chain and labour problems, expects to deliver its first Dreamliner to Japan's All Nippon Airways in the third quarter of this year.
Rolls-Royce said it has now delivered Trent 1000 engines to Boeing to support 787 test flights for ETOPS approval of the engine/aircraft combination.
The company said its Trent engines power five out of the seven aircraft in the 787 flight programme.