ADDIS ABABA, Ethiopia — Ethiopian investigators have concluded in a new analysis that the March 2019 crash of an Ethiopian Airlines flight was caused by design flaws in the Boeing 737 Max plane and not by the performance of the airline or its pilots, adding to the scrutiny of the jet model that has been involved in two recent deadly crashes.

An interim report released on Monday by the Ethiopian Aircraft Accident Investigation Bureau comes almost exactly a year after Ethiopian Airlines Flight 302 went down shortly after departing Addis Ababa, killing all 157 people onboard. The crash occurred five months after a similar Max owned by Lion Air of Indonesia crashed minutes after takeoff, killing 189 people.

Although several factors have been cited in the two crashes, malfunctions related to automated software known as MCAS were listed as key in both accidents.

The two crashes thrust Boeing into the biggest crisis in its history, leading to the ouster of its chief executive, Dennis A. Muilenburg, and drawing government scrutiny over the design, development and certification of the 737 Max. The subsequent global grounding of the 737 Max, Boeing’s most popular passenger jet, and the halting of its production are projected to cost the company $18 billion.