While Boeing continues installation of the 787 wing fix, engineers have returned to the drawing board to redesign a crucial portion of the reinforcement, Flightglobal affiliate FlightBlogger reports.
As a result, sources say the 2009 first flight target could be in jeopardy as engineers work to redesign the fix for four remaining wing stringers.
Scott Fancher, vice-president and general manager of the 787 programme commented:
"The design of the side-of-body solution is on track. Installations of the fittings are proceeding well and we are pleased with the progress we are making on this important effort. We continue to be on track to fly the 787 by the end of the year."
Boeing will provide a more detailed update on the side-of-body reinforcement on 21 October during the company's third quarter earnings call.
Boeing announced on 23 June that it had cancelled plans for first flight due to structural deficiencies requiring reinforcement at the side-of-body of the aircraft where the wing meets the centre wing box.
The company began installing the existing reinforcements on the static structural and flight test 787s on 23 September.