General Electric’s share of the total Boeing 787 announced orderbook has officially broken the 50% barrier with the selection by Air France-KLM of the GEnx-1B engine to power its mixed fleet of 37 owned and leased 787-8s and 9s.

The deal maintains GE’s lead in the 787 which it has held over the competing Rolls-Royce Trent 1000 engine largely due to an early advantage in fuel burn as well as broader leveraging of fleet support deals involving GE90-powered 777-300ERs. The total engine order, which covers 25 787-9s and 12 leased 787s, is valued at more than $1.7 billion says GE, which adds the operator has also signed an agreement that will let Air France-KLM offer maintenance, repair and overhaul (MRO) services for the GEnx-1B.

GE says the deal licenses Air France-KLM “to perform maintenance and overhaul work on the GEnx-1B,” while GE will also provide technical support and assistance on overhaul workscoping and component repair licenses, comprehensive material support and training.

While the Air France-KLM selection was widely expected given existing links between the airlines and GE, the announcement officially marks the point at which the U.S. engine maker assumes the majority of the engine selections yet made for the 787.

According to Boeing figures the latest announcement means that GE has been selected to power 535 of the 1,031 787 aircraft of all versions currently on firm order. Of the remainder 253 are officially logged as Rolls-powered, with the balance of 243 (23.5%) currently marked as unselected.

However according to engine maker sources the actual number of firm selections is greater for both companies with airlines having picked the GEnx-1B for 564 787s, and the Trent 1000 for 321. Although Boeing cannot confirm these numbers, if verified they mean that the backlog of undecided 787s to fight over has shrunk to just 146 aircraft, or around 14% of the firm orderbook. The updated numbers also indicate GE’s share of the firm 787 market has climbed to almost 55% with Rolls taking over 31%.

Rolls is meanwhile mounting a comeback campaign with the radically revised Trent 1000 TEN which was launched at the 2012 Farnborough airshow. To be rated at 78,000 lb. thrust, the engine is in development for all versions of the 787 including the -10 which received the go-ahead last year.

The engine, which will be built in Singapore, will enter service on the 787-8/9 in 2016 and on the stretched 787-10 in 2018. Assembly of the first-TEN engine is underway and the unit is due to enter testing later this month. Eight engines are scheduled to take part in the certification program which includes a stint on Rolls’ 747-200 flying testbed in mid-2015. Certification is expected at the end of next year.