Progress continues in 2018 on Aerojet Rocketdyne's RS 25 engines for SLS with the testing of 3-D printed parts to speed up production and reduce costs for future launches. FOX News reported on these successful tests in the link above.
As NASA reported following the successful test:
"NASA engineers picked up this year where they left off in 2017, conducting a certification test of another RS-25 engine flight controller on Jan. 16, 2018, on the A-1 Test Stand at Stennis Space Center near Bay St. Louis, Mississippi. The 365-second, full-duration test came a month after the space agency capped a year of RS-25 testing with a flight controller test in mid-December. A 3D printed part tested in December was tested again. This rocket engine component, a pogo accumulator assembly, is part of an ongoing series of tests with parts made using advanced manufacturing techniques that will make building future engines more affordable.
"For this 'green run' test, the flight controller was installed on RS-25 developmental engine E0528 and fired just as during an actual launch. Once certified, the flight controller will be removed and installed on a flight engine for use by NASA’s new deep-space rocket, the Space Launch System (SLS). NASA is building SLS as the most powerful rocket in the world, designed to carry humans on the Orion spacecraft and enable missions to the Moon and Mars.
"Launch of the SLS rocket will be fueled by four RS-25 engines firing simultaneously to generate 2 million pounds of thrust and working in conjunction with a pair of solid rocket boosters to produce more than 8 million pounds of thrust."