Rumours of further delays on Boeing's prestigious 787 Dreamliner programme have once again gained momentum with Goldman Sachs circulating a client note late last week which indicates that the plane's customers may have to wait an additional three months, at the very least, to take delivery.

In the note, Sachs analyst Richard Safran said, "Our sources indicate 787 power-on, scheduled for March end, may be delayed until the end of June. First flight, expected three months after power-on, may be further delayed. We now think deliveries will start in the third quarter of 2009 versus the current 'early '09' target."

Boeing, in response to market queries, said that it has committed itself to a comprehensive assessment of 787 production and this report is due March-end. Till the report came out the company was still committed to "power-on early April and fly late June."

The Dreamliner was originally scheduled to fly September 2007 and slated for delivery to launch customer All Nippon Airways in May this year.

After recent delays the re-worked schedule has the first delivery slated for the first quarter of 2009.

In his note, Safran told clients that "final assembly of 787s, 4 through 6, are also delayed, which is significant as we think Boeing needs six aircraft in flight test for 11 months." The note further said, "in our view, Boeing continues to underestimate the amount of work required on the 787."

Interestingly, the note has pointed to wiring as an area of concern. Similarly delayed, the Airbus A380 super jumbo battled wiring issues for an inordinately long time before resolving it successfully.

Sachs is now lowering its 2009 delivery forecast for the 787 to 50 units from 80. Boeing had originally planned to deliver 109 units in 2009.

The Dreamliner has seen its delivery dates pushed back twice - first time for six months in October last year, and once again for three months in January this year.

Further delays will not only affect customer airlines seriously but also leave Boeing facing significant penalties.