Boeing said Thursday that its Gresham factory will start making additional parts for three of its flagship jets, bringing work in house that had previously been done by a supplier in another country.

The Gresham facility will start making a component known as a flap actuation system, used to extend and retract wing flaps during flight. Boeing says the parts add lift for take-off or increase drag when an aircraft needs to slow down.

Boeing employs more than 1,600 at its 87-acre site along Northeast Sandy Boulevard. The new work won't bring additional jobs, according to the company, but enables the site to maintain its current size.

"As we gain in productivity each year, if you don't bring new work in then your size shrinks," said Don Hendrickson, a Boeing finance manager in Gresham.

The decision to stop outsourcing the work reflects improved manufacturing technology within Boeing, according to Hendrickson. He said the company is continually adding capabilities to its equipment, and so it's now more efficient to do some work internally than to hire contractors. Boeing declined to say where the flap actuation system had been made previously.

Boeing operates in Gresham under three separate packages of local property tax exemptions, including one that took effect last year valued at more than $10 million.

The company, like other manufacturers, has been eager to tout domestic production since the election of President Donald Trump last fall. Last week, Boeing hosted the new president at a factory in South Carolina.

Historically, workers at the Gresham factory have engineered and machined parts from a variety of metals for Boeing's 737, 767 and 787 jets. Boeing said it will use the flap actuation systems on its 737, 737 MAX and 777 aircraft.

-- Mike Rogoway; twitter: @rogoway; 503-294-7699