If you are attending a repair or manufacture inspection (commonly called a witness or inspection point) at a facility (OEM or non-OEM) alone and are not truly familiar with the repair or manufacture process/procedure then I would recommend having a third party inspector, specializing in the specific equipment or process, accompany you.
Third party inspectors visit the same shops many times a year and are familiar not only with the shop but the processes. Many engineers only visit a particular repair or manufacture of a specific piece of equipment once or twice in their careers. Therefore, you will benefit from their experience as well as what you will learn during the inspection.
Additionally, most third party inspectors can be called as an expert witnesses should things go south after the repair or during a warranty claim.
If the repair/manufacture facility is not the OEM then I suggest even stronger that you have a third party attend the inspection.
Locate a third party inspection agency that can provide the talent you are looking for. Telephone them, tell them what you are looking for and ask for them to send you candidates' resumes/CVs. Then conduct a telephone interview with each candidate. In general inspection agency rates are competitive so don't worry about the rates. However, most experts are independent consultants and do charge more for their talent; they are also harder to locate.
The cost, in comparison to the consequences, of an uninformed witness/inspection visit can be greater than the price of the repair or manufacture when you are trying to get a unit back on line or complete a project on schedule.
