This paper presents our research on devising a dependability assessment method for the upcoming OGSA 3.0 middleware using network level fault injection. We compare existing DCE middleware dependability testing research with the requirements of testing OGSA middleware and derive a new method and fault model. From this we have implemented an extendable fault injector framework and undertaken some proof of concept experiments with a simulated OGSA middleware system based around Apache SOAP and Apache Tomcat. We also present results from our initial experiments, which uncovered a discrepancy with our simulated OGSA system. We finally detail future research, including plans to adapt this fault injector framework from the stateless environment of a standard web service to the stateful environment of an OGSA service.