Boeing said Tuesday it does not expect a problem that came up during testing of its new long-haul 777X aircraft to significantly affect aircraft design or timetable.

Boeing did not disclose details about the problem. A source close to the matter who spoke on condition of anonymity said a door of the plane blew out during the test.

Boeing last week said it suspended “final load testing,” which is overseen by inspectors from the Federal Aviation Administration (FAA) and during which planes are subjected to loads and stresses beyond normal flying conditions.

“While our root cause assessment continues, at this time we do not expect that this will have a significant impact on aircraft design or on our overall test program schedule,” Boeing said.

“We remain fully focused on safety as our highest priority, as we subject the 777X to a rigorous test program prior to first flight.”

The 777X was originally scheduled to take off on its first test flight this summer. That date has been postponed until early 2020 by Boeing, due to problems with its General Electric engine.

The suspension of the test on the 777X comes as Boeing is in the process of completing changes required by regulators on the 737 MAX, which has been grounded worldwide after two crashes that resulted in 346 deaths.

Civil aviation authorities have stepped up their inspections since the disasters, most notably the FAA, which has been accused of cozy ties with Boeing.