Boeing’s board of directors is expected to decide as early as its next meeting in April whether to give the Commercial Airplanes division authority to offer the proposed 777X derivative to airlines.

The milestone move, if confirmed, puts Boeing at the start of a six-year development track culminating with the entry into service of the first of two new 777 family members in 2019. The extended twinjet series will include a 777-8X, sized to succeed today’s 777-300ER, and a larger 777-9X which opens up new territory in the 400-plus seat, long range market.

Before the 777X proposal goes before the board, however, Boeing needs to finalize one of the most crucial decisions it has faced over the new development: whether to offer the larger twin with a choice of engines. The longer range 777-200LR/300ER versions, which now account for all but a handful of 777 orders, are powered by General Electric

GE90-115 engines provided under a sole-source deal agreed in 1999.

According to airline sources, Boeing is believed to be on the verge of selecting General Electric’s GE9X under a similar agreement for the follow-on 777X. Boeing had been considering offering Rolls-Royce’s proposed RB3025 as an alternate to the GE9X, mostly under pressure from the airlines which wanted the competitive benefit of an engine choice. However, having eliminated late last year a study version of a higher thrust variant of Pratt & Whitney’s geared turbofan, it now seems Boeing is once again set to continue along the sole-source path with GE.

Boeing declines to comment on whether the 777X program is about to be proposed to the board for authority to offer (ATO). It says only that “customers are happy with the airplane design and we are pleased with where we are in the process. We are aggressively moving forward per our plan and working with our customers on the requirements. While we haven’t set a firm timeline or launched the program, we’ve consistently talked about a potential EIS around the end of the decade.”

The manufacturer also declines to comment on whether the engine selection has been made, saying that its “decision regarding engine options will be based on the right technical solutions available at the right time under the right business arrangements to meet our customers’ requirements.” Neither Rolls-Royce nor GE are willing to comment on the status of their 777X proposals.

GE has made no secret of its long-term plan to maintain its dominance on the 777 by going ahead with development and testing of the GE9X it is readying for the 777X. The engine-maker is running several technology demonstration efforts to support FAR33 engine certification in 2018, and entry-into-service in 2019.

Commenting late last year on GE’s decision to plow on with tests despite Boeing’s apparent indecision in 2012, GE90 general manager William Millhaem said “even though Boeing is still figuring out what they want to do we’re doing the technology. It’s the right thing to do for the industry.”