Last month, the aerospace company said the cumulative impact of a series of issues could push the first delivery "a few weeks into 2011." Those problems included supplier workmanship issues related to the horizontal stabilizer, as well as instrumentation delays.

The latest change in the delivery date follows an assessment of the availability of an engine needed for the final phases of flight tests this fall. In a statement Friday, Boeing spokeswoman Yvonne Leach said Boeing is working closely with Rolls-Royce to expedite engine availability.

KIRO 7 Aviation Analyst Scott Hamilton has also learned that a Rolls-Royce Trent 1000 engine blew up on a test stand.

WATCH IT: New Delay Comes After Engine Test Failure

"The first launch customer, All Nippon Airways, has the Rolls-Royce engine on its airplanes. So, clearly this is a big problem and we really don't know when it's going to be solved," said Hamilton.

Boeing's spokeswoman says flight testing continues as planned. But Hamilton reports on his blog that in the word of one customer, the flight test program is being "babied."

"The flight test hours have fallen far short of expectation and a GEnx-powered unit, #6, hasn’t flown at all and will be at least three months behind schedule before its first flight. The reason is unknown," wrote Hamilton.

The 787 is made of many composite materials designed to make it lighter and more fuel-efficient than comparable planes already in the sky. Its development has been hit by delays.

Aviation Transport World reports that Kenya Airways may consider canceling the nine 787's it has on order.

Boeing says the latest schedule revision will not affect the company's financial guidance. The original delivery date for the 787 was May 2008.