NASA and Boeing officials said Tuesday that they have successfully removed two valves from the Starliner spacecraft and have shipped them to Marshall Space Flight Center in Alabama for further analysis.

The forensic examination—the two valves will be inspected with a variety of techniques, including a CT scan—is part of Boeing’s ongoing effort to diagnose the “stuck” valve issue that caused an abort of Starliner’s uncrewed test flight on August 3. With less than five hours remaining in the countdown to launch, during a routine procedure, 13 of the 24 valves that control the flow of dinitrogen tetroxide oxidizer through the service module of the spacecraft would not cycle between closed and open.

An initial diagnostic effort at the launch pad yielded no results, so the Atlas V rocket and spacecraft were rolled back to an integration facility. After more inspection and testing there, engineers decided to “de-stack” the spacecraft and return it to Boeing’s spacecraft processing building at Kennedy Space Center. This eventually led to further dissection of the vehicle and removal of several valves.