Add another ongoing construction project to the list at Boeing’s 787 plant in North Charleston.

According to a county government filing, the plane maker has begun upfitting another 77,000 square feet in its final assembly factory by the airport.

Hitt Contracting submitted the one-page contractor’s notice of project commencement this week. It says the “4th floor fit out” began April 26 but gives no more details.

A Boeing spokeswoman has not responded to a request for more information.

It’s just the latest upgrade or development at the Boeing complex.

Late last summer, Boeing began expanding both its aft-fuselage factory and its campus paint shop. Shortly thereafter, work began on 30,000 sq. ft. of lab and office space in the final assembly building.

And then, in late January, construction crews began building a Dreamlifter Operations Center on the back of the mid-body building, adding a staging area for parts ready to be shipped out via the modified 747s.

Meanwhile, Boeing last month announced an agreement to invest another $1 billion and hire 2,000 more people in South Carolina over the next eight years in exchange for $120 million from the state and other tax breaks from the county.

In addition to land, building and job growth, the North Charleston campus is also diversifying beyond 787 work. It’s in the process of bringing on 20 737 workers and many more information technology staff.

Reach Brendan Kearney at 937-5906 and follow him on Twitter at @kearney_brendan.