Auditing AS9100D with transition training only

Answer: The process of auditing is to compare what is actually happening in a process against the planned arrangements. That being said, if you already know how to audit then what you need to update is your understanding of the planned arrangements, and an awareness and transition course will have given you this knowledge. In many cases this is all that would be needed to audit against AS9100 Rev D. I say in most cases because it is up to the company to determine the competence required for internal auditors, so if the company competence requirements are understanding auditing, understanding AS9100 Rev D and understanding internal company processes then it is the knowledge needed to meet these requirement that needs to be demonstrated, and the tr ansition course could be one way to do this.
For some more information on the changes see this article: https://advisera.com/9100academy/knowledgebase/as9100-rev-d-vs-rev-c-what-has-changed/