 BP challenged the revocation and the probation was lifted as planned in December 2011.In the settlement of a civil suit, in July 2011 investigators from the U.S. Department of Transportation's Pipeline and Hazardous Materials Safety Administration (PHMSA) determined that the 2006 spills were a result of BPXA's failure to properly inspect and maintain the pipeline to prevent corrosion.PHMSA issued a Corrective Action Order (CAO) to BP XA that addressed the pipeline's risks and ordered pipeline repair or replacement.