Factory workers at Boeing have voted to accept a contract offer and end their strike after more than seven weeks, clearing the way for the company to restart idled Pacific Northwest assembly lines. But the strike was just one of many challenges the troubled US aerospace giant faces as it works to return to profitability and regain public confidence. Boeing's 33,000 striking machinists disbanded their picket lines late Monday after leaders of the International Association of Machinists and Aerospace Workers district in Seattle said 59 per cent of union members who cast ballots agreed to approve the company's fourth formal offer, which included a 38 per cent wage increase over four years. Union machinists assemble the 737 Max, Boeing's bestselling airliner, along with the 777 or triple-seven jet and the 767 cargo plane at factories in Renton and Everett, Washington. Resuming production will allow Boeing to generate much-needed cash, which it has been bleeding. Even for a company the