Boeing has submitted a request for proposal to 787 supplier Hamilton Sundstrand for its larger -9.
Hamilton Sundstrand, which supplies the electrical and environmental control systems for the 787-8, received the RFP on 9 July, says Bob Leduc, president for Hamilton Sundstrand's 787 programme.
While Leduc say that the company has not yet had the chance to review the entire document, "it appears Boeing has made a concerted effort to make the -8 and -9 as common as possible. It appears there will be some electric system modification and the [auxiliary power unit] will be common between the two models".
Leduc explains the largest system change "will be the environmental control system whose capacity will have to be increased to accommodate the higher passenger count of the -9".
The 6.1m (20ft) stretched -9 will seat between 250 and 290 passengers compared to 210-250 carried on the smaller -8, which will be delivered to Japan's All Nippon Airways by year-end.
Leduc says that even with the larger cabin for the -9, the electrical power requirements will remain the same on the aircraft's engine and APU generators.
Boeing achieved firm configuration of the -9 on 1 July, following a comprehensive internal review of the aircraft's overall capability and basic design.
Air New Zealand, launch customer for the 787-9, is expected to take the first delivery at the end of 2013.