There's an issue with an SLS engine controller.

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Ars Technica Rocket Report reports that Aviation Week (subscription required) reported:
"This past weekend, rumors emerged about a problem with the controller for one of the four RS-25 engines that power the Space Launch System. NASA has not officially commented, but Aviation Week's Irene Klotz spoke with Aerojet's RS-25 program manager, Jeff Zotti. Troubleshooting the problem began on November 22, Aviation Week reported.

Schedule impacts yet to be determined ... If necessary, "replacing a line or a component … we're probably talking about multiple days. Replacing an engine, we're probably talking about multiple weeks," Zotti told the publication. "On top of that, we have to assess what that does and how that affects the vehicle and the integration activities that are going on," he added. All of that must be factored into a potential delay of the launch, presently scheduled for February 12. A summer launch for the SLS now seems far more likely than spring.:

https://arstechnica.com/science/2021/12 ... s-orbital/

The link is to the entire Rocket Report. This bit is way down to the bottom of the report.

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