The delivery date revision follows an assessment of the availability of an engine needed for the final phases of flight test this fall.
While Boeing works closely with Rolls-Royce to expedite engine availability, flight testing across the test fleet continues as planned.
Boeing said last month that the cumulative impact of a series of issues, including supplier workmanship issues related to the horizontal stabilizer and instrumentation delays, could push first delivery of the 787 a few weeks into 2011. The delay in engine availability has extended that estimate to mid-first quarter 2011.
The schedule revision will not affect the company's financial guidance.