I have participated in 1 unannounced FDA audit and 1 MDSAP mock audit in the medical industry before. Prior to each audit, there are a series of training sessions for audit preparation that is mandatory for those who will be participating either directly (in the audit room or command center) or indirectly (owners of processes like SOPs) must complete. For the first FDA audit, I was only an intern, so I helped in preparing documents that were needed during the week of the audit and completing my training session. For the MDSAP mock audit, I was a full-time employee who manages the repository for our design history files (DHF) and is the owner of the SOP for that system. So even though I had more responsibility, my role was very similar. I located DHF documents that were required per project, which were primarily project quality plans, product development requirements, system requirement specifications, technical and peer review checklists, verification and validation documentation, as well as risk management files (risk assessments, FMEAs, risk management reports, hazards analysis, etc.). My mindset approaching the audit was pure panic. I was very nervous for no reason. In the audit, it was amazing to see how each department worked as one unit for providing the documents in a timely manner. The majority of the people in the Command Center (where document requests are sent, documents are located, and printed for the auditor) were employees from either Quality, Customer Service, or Product Lifecycle Management, with the exception of myself. The people who were in the room with the auditor were the supervisors of the Quality and Design Control departments. Every auditor is different and there is no agenda for what projects, documents, or CAPAs/SCARs they will be looking into (even though they do provide one) because each auditor has a different focus during their investigation. When an auditor asks you a question, you should only reply with a short and clear answer, avoiding redirecting an auditor down an additional path. Also, if you do not know something, there is nothing wrong with saying that you do not know and will contact the subject matter expert and return the information to the auditor as soon as possible. It was a great experience, and the audits are a great way to ensure all documentation is up-to-date and of highest quality.

For those who are interested in what an MDSAP audit it:
https://www.fda.gov/MedicalDevices/InternationalPrograms/MDSAPPilot/