The company has delivered eight 787s this month, leaving just six for the remainder of the year, according to industry sources and plane-spotting blog All Things 787. Concern about the target rose after French seat maker Zodiac Aerospace SA said on Dec. 11 that production delays on seating would continue to affect its profits Boeing declined to comment. The pace of 787 deliveries is important to Boeing investors as a gauge of progress in lowering the cost of building each jetliner. In theory, aircraft become cheaper to produce over time as workers learn procedures and iron out kinks on the factory floor. Three years after the 787 entered service, Boeing continues to lose as much as US$30 million on each 787 it produces, according to Richard Aboulafia, an analyst at Teal Group. He bases the figure on Boeing's deferred production cost, which reached US$25.2 billion in the third quarter, more than analysts expected.