“The first phase of the engine tests was really a warmup to make sure that everything looked good prior to running the engine. Then we moved to the actual first engine start. That took the engine out of the preservation mode that it had been in since installation on the aircraft. It was the first check to see that it was operating properly and that all the systems it impacted – hydraulics, electrical system, environmental control systems, etc. – seemed to be working.”
Source: Jay Brandon, NASA’s X-59 chief engineer, commenting on the start of a new phase of testing for the NASA Quesst mission