Boeing says it will be several weeks before it fully resumes building passenger planes, as factory workers return following a strike that lasted nearly two months.

A Boeing spokesperson said Tuesday that the delay in restarting plants in Washington state and Oregon is due to multiple steps needed to resume production.

Each employee will be briefed on their role and safety requirements as they return, and the company will make sure that training certifications are current, the spokesperson said.

About 33,000 workers represented by the International Association of Machinists and Aerospace Workers began a strike Sept. 13 over wages and pensions. They voted last week to accept a Boeing contract offer, and must return to work by Tuesday.

The strike shut down production of the 737 Max and 777 passenger planes and a cargo-carrying version of the 767 plane. Boeing continued building 787s, which are produced by nonunion workers in South Carolina.

The strike cut deeply into the cash that Boeing receives when it delivers new planes.

Boeing said Tuesday that it delivered 14 planes in October including planes that were finished before the strike began. Boeing said it took orders for 63 planes, including 40 737 Max jets by leasing company Avia Solutions Group.