Boeing Co on Wednesday stuck to its goal of generating free cash flow this year and said it was in the "final stages" of preparing to restart 787 Dreamliner deliveries.

Shares of the planemaker rose 3.6% in premarket trading, even as it posted an adjusted second-quarter loss on charges related to its defense and space unit.

Some analysts were skeptical about Boeing achieving its free cash flow goals this year, as the company works through industry-wide supply-chain disruptions and labor shortages that have hobbled production.

A resumption in deliveries of the wide-body Dreamliner would mark a significant milestone for the company that is working to turn around its fortunes amid a resurgence in air travel.

Deliveries of the Dreamliner were halted for more than a year by inspections and repairs to fix manufacturing flaws in an industrial headache costing the company about $5.5 billion.

"Even as we navigate a difficult environment, we are making progress across key programs and are beginning to hit significant milestones," Chief Executive Dave Calhoun said in a letter to employees.

Boeing posted a core loss of 37 cents per share in the quarter through June, compared with a year-ago profit of 40 cents per share.

(Reporting by Abhijith Ganapavaram in Bengaluru and Rajesh Kumar Singh in Chicago; Editing by Saumyadeb Chakrabarty)