The Boeing 737 MAX, the aircraft involved in two deadly crashes in the past five months, is battling public scrutiny from lawmakers as a number of federal investigations kick off to examine how the aircraft were certified.

“We plan to dig deep into the issues surrounding the recent accidents over the coming weeks and months,” House Transportation and Infrastructure Committee Chairman Peter DeFazio, D-Ore., said in prepared remarks during a hearing on infrastructure investment in U.S. airports late last month. “Tragedies like these should not happen.”