The problems emerged once the planes got to the US and Boeing engineers got a look at them. Talk about newbie mistakes on MHI's part.

https://leehamnews.com/2017/01/23/mr...ayed-mid-2020/

The aircraft development started with a Japanese team and this team did not have the expertise needed to understand all the implications of modern certification requirements.

As the Seattle development center and the Moses Lake test center came online, experienced engineers coming from, e.g. Boeing, got insight into the program. The Western workforce started finding oversights in the work of the Japanese team.

The first conclusion of the reviews these teams made was the test program was not realistic. It was based on how aircraft were tested and certified historically. You fly and measure and then decide if things are OK.

This is not how tests are done today. You prepare the test thoroughly, you simulate the test results in a ground environment and you only fly when the ground tests show that you can have a fault-free test flight. Test flights are made to verify results, not to explore developments.

As the international engineering team dived deeper into the design of the MRJ, it found more issues. The MHI press release states that the project needs “revisions of certain systems and electrical configurations on the aircraft to meet the latest requirements for certification.”