A Boeing 737 carrying 132 people crashed early Monday in China. Although Boeing’s 737 has faced extraordinarily high-profile safety concerns over the past three years, the plane that crashed Monday was a different version of the aircraft than the embattled 737 Max that shook Boeing to its core. The cause of Monday’s crash has yet to be determined. The plane had been in service since 2015. The flight, operated by China Eastern Airlines, was flying from the southwestern Chinese city of Kunming to Guangzhou when it crashed. Here’s what we know about the aircraft. The 737-800 The crashed China Eastern Airlines plane was a Boeing 737-800. It’s the most common version of Boeing’s jets now in service, and it is the workhorse of many airlines’ fleets. There are 4,502 of the 737-800s now in service worldwide, according to aviation analytics firm Cirium, making it by far the most common Boeing\n \n (BA) aircraft in use today. It is the most common plane model in the United States, where there are 795 in service, as well as in China, which has 1,177 in service. And it’s the second-most-common plane in use worldwide, behind only the A320 made by Boeing\n \n (BA) rival Airbus\n \n (EADSF). The 737-800 is an older model aircraft that has been replaced by the 737 Max. Previous safety issues Boeing started deliveries of the 737-800 in 1998 but has not delivered a civilian version of the plane since two went to China Eastern in January 2020. The Boeing 737-800 is part of a class of Boeing jets known as 737-NG. The “Next Generation” planes have had safety issues cited by US regulators, although none of those rose to the level of requiring the planes to be grounded. In 2018 a single passenger was killed on a Boeing 737-700, the other plane in the Next Generation family. In that accident, an engine fan blade on a Southwest Airlines flight broke and caused part of the engine covering to hit the side of the plane. It smashed one of the windows, and the cabin rapidly depressurized. The crew was able to land the plane safely, but a woman sitting next to that window was killed. In 2019 the National Transportation Safety Board recommended that Boeing redesign part of the jet’s engine covers to prevent them from flying into the plane in the event of a similar malfunction. Boeing agreed to make the change. In some older planes, a part used to keep the wings in place was found to have cracks. Those cracks temporarily grounded a handful of the 737 NGs. Other fatal accidents involving the 737-800 have occurred when planes were landing in bad weather and missed or skidded off runways. Another one was shot out of the sky by a missile in Iran in 2020. There has not been a fatal accident with a Chinese airline since 2010, according to the Aviation Safety Network. Boeing issued a statement Monday saying it is working with both US and Chinese safety authorities. “Our thoughts are with the passengers and crew of China Eastern Airlines Flight 5735,” the plane maker said. “We are working with our airline customer and are ready to support them. Boeing is in contact with the US National Transportation Safety Board and our technical experts are prepared to assist with the investigation led by the Civil Aviation Administration of China.” The 737 Max Boeing’s 737 Max suffered two fatal crashes, in 2018 and 2019, that were shown to be caused by a design flaw and led to a global grounding of the aircraft. Those crashes resulted in the 20-month grounding of the 737 Max, costing Boeing tens of billions of dollars. The 737-800 does not have the feature that caused the 737 Max crashes. — CNN’s Richard Quest, Yong Xiong and Helen Regan contributed to this report.