Ethiopian crash investigators have tentatively concluded that the crash of a Boeing Co. 737 Max last year was caused by the grounded plane’s design, according to a draft report that’s being circulated to participants in the probe.

The conclusions, which say little or nothing about the performance of Ethiopian Airlines or its flight crew, have raised concern with some participants in the investigation, according to three people familiar with the situation.

The Ethiopian draft contrasts with conclusions by Indonesia’s National Transportation Safety Committee after a prior 737 Max crash in October 2018. Indonesian investigators cited multiple factors in the accident, including the plane’s design, poor maintenance and the pilots’ actions.

Rather than release a full report, the Ethiopian Aircraft Accident Investigation Bureau plans to publish an interim update before the anniversary of the March 10, 2019, crash.

The conclusions, which include recommendations, are only in draft form and could be altered before release, said the people, who requested anonymity to discuss the sensitive matter. It’s possible the US National Transportation Safety Board could request changes to the report or offer a dissenting opinion.

Under United Nations provisions, other nations participating in an accident investigation should get 60 days to comment on a final report. The Ethiopian report wasn’t sent out for comment until about a week ago, according to one of the people involved.

The provision doesn’t apply to an interim report, but they typically don’t include formal conclusions about the cause.

The NTSB has received a copy of the draft interim report, spokesman Eric Weiss said. The safety board can’t comment on the contents of the draft, Weiss said.

A Boeing spokesman declined to comment on the draft.

The Federal Aviation Administration said in a statement it can’t comment before the report is released. The FAA isn’t a direct participant in the accident investigation, but is providing technical support under the NTSB because it certified the plane.

The Ethiopian Transport Ministry and Ethiopian Airlines didn’t immediately respond to messages left after business hours.

Ethiopian Airlines Flight 302 suffered a malfunction to a sensor moments after liftoff. This triggered a safety feature known as Maneuvering Characteristics Augmentation System or MCAS that was programmed to automatically lower the nose and activated about 80 seconds into the flight.

A preliminary report released by the Ethiopian investigators last April made clear that the MCAS system played a role in the accident. But it also said that pilots had let the plane fly too fast, which made it more difficult to control.

The pilots began a Boeing procedure to disable MCAS, but apparently reactivated the system shortly before the plane entered a steep dive, according to the preliminary report.

A committee of the US Congress released preliminary findings from its investigation on Friday, blasting US regulators and Boeing for a series of design and safety blunders.

The 737 Max’s design and development “was marred by technical design failures, lack of transparency with both regulators and customers, and efforts to obfuscate information about the operation of the aircraft,” the House Transportation and Infrastructure Committee said in a summary of preliminary findings from its nearly yearlong probe of the aircraft.