This paper presents the preliminary results of an "a posteriori" exercise of application of a Requirements Traceability Automation Tool (RT tool) to a set of documents. The documents have been prepared according to established Space System Engineering methodologies and with attention to text quality, but without attention to requirements traceability because the processes and methodologies used during their preparation predates the emergence of the processes and methodologies developed by Requirements Engineering (RE). This study is intended to determine some of the benefits of using a RT tool when compared with the previously used processes and methodologies. The set of documents under scrutiny have been prepared in the frame of the development of the CBERS-3 satellite (China-Brazil Earth Resources Satellite) and is composed of system, subsystem and equipment specification and covering documents related to the Electrical Power Subsystem (EPS) of the satellite. We present a summary of the current status of the study and some examples of requirements problems discovered when reviewing the text prior to entering the documents in the RT tool. Up to now, the study has definitely demonstrated that the use of a RT tool, regardless of its functionalities, compels the writer to pay attention to individual requirements, to their relationships and to avoid construction of long elaborate texts that are source of errors and misinterpretations.