ULA successfully delivered the OA-6 Cygnus spacecraft to its precise orbit as planned on March 22. During the launch, the system experienced a premature first stage shutdown. Atlas is a robust system.
The Centaur upper stage compensated for the first stage anomaly, delivering Cygnus to a precise orbit, well within the required accuracy. The ULA engineering team has reviewed the data and has determined an anomaly with the RD-180 Mixture Ratio Control Valve (MRCV) assembly caused a reduction in fuel flow during the boost phase of the flight.
In addition to analysis and testing, all RD-180 engines are being inspected.
