Nearly a week after a panel blew off an Alaska Airlines 737 Max 9 aircraft midflight, lawmakers and federal regulators are starting to look to the Boeing plane’s troubled history to understand what happened — and what didn’t. On Thursday, fingers started pointing. The Federal Aviation Administration announced Thursday morning it was opening an investigation into Boeing’s role in last Friday’s fuselage blowout. The investigation would determine if Boeing properly complied with all regulations meant to ensure its planes were safe and built correctly. Later that day, Sen. Maria Cantwell, D-Washin…