WASHINGTON/SEATTLE – After nearly a decade of review, the Federal Aviation Administration on Monday certified Boeing‘s 737-7 passenger jet for commercial service, clearing the smallest member of the 737 MAX family to begin airline deliveries.

The FAA said the amended type certificate follows years of work to resolve technical issues and complete an extensive review of the aircraft’s design and safety analyses.

Regulators said they scrutinized flight controls, system safety, human factors and other critical areas while requiring additional testing, design changes and analysis before approving the aircraft.

The certification required Boeing to incorporate changes mandated under the Aircraft Certification, Safety and Accountability Act and recommendations from the National Transportation Safety Board, including updates to flight-control software, the flight crew alerting system and a redesigned engine anti-ice system.

The FAA said the changes provide pilots with clearer warnings and prevent engine inlet overheating that could weaken surrounding structures.

The 737-7 is designed to carry 135 to 160 passengers in a typical two-class configuration. It also has the longest range in the MAX lineup, capable of flying up to 3,800 nautical miles (7,040 kilometers).

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

Boeing said the aircraft burns 20% less fuel and produces 20% fewer carbon dioxide emissions than the airplanes it typically replaces while cutting its noise footprint by 50%.

Southwest Airlines, the launch customer for the 737-7, is preparing to take delivery of the first aircraft.

The FAA said safety inspectors will remain at Boeing production facilities to monitor manufacturing, including the company’s safety management system and safety culture.

Boeing has booked about 300 firm orders for the 737-7