Bill Brown’s appointment as CEO of Maplewood-based manufacturing giant 3M in March marked a change of direction for the company. Unlike his predecessor Mike Roman, who had been with 3M for over three decades, Brown is a company outsider who previously worked in aerospace and defense. Brown takes over at a critical time for 3M, which has faced litigation related to its allegedly defective military-grade earplugs and the proliferation of PFAS, or “forever chemicals,” which have been found in drinking water throughout the U.S. and world. Upon his appointment, Brown said he was looking forward to building on Roman’s “significant positive changes” at the company.