Aug. 3 (UPI) — After years of delays, the Federal Aviation Administration has certified the Boeing 737 Max 7, the smallest model in that line, to fly passengers.

The FAA delayed the certification for reasons including the redesign of an engine anti-icing system and other safety and manufacturing issues. In addition, there was increased inspection after Max 8 models, which had already been certified, crashed in 2018 and 2019.

“The approval reflects years of sustained work to resolve complex technical issues and complete a thorough review of the airplane’s design and supporting safety analyses,” the FAA said in a statement.

“Throughout the process, the FAA performed or directly reviewed significant work involving flight controls, system safety assessments, human factors, flight-crew alerting and other novel, complex or safety-critical areas, while also requiring testing, design changes, and additional analysis when necessary.”

Airlines will now need to work the planes into schedules, so it may take a while before passengers see them. They had originally expected to have the Max 7 models flying before the COVID-19 pandemic.

“This important certification validates the rigor of our airplane’s design and recognizes the determination and resilience of our 737 MAX development team,” said Stephanie Pope, Boeing Commercial Airplanes president and CEO, in a statement Monday.

Boeing’s stock rose about 8% in Monday afternoon trading following the news.

The company is still waiting on certification of the 737 Max 10 model, the largest in the line, which has also been delayed for years.

In mid-July, the FAA resumed allowing Boeing to issue airworthiness certificates for its 737 Max aircraft and 787 Dreamliners. The manufacturer lost that authority after the Max 8 crashes, which killed more than 300 people. It has since escalated production of those airplanes.