I am wondering if other repair shops test fly aircraft before or after a paid repair or mod service these days, as this could be considered commercial flying. From an FAA website: Do I need a Section 333 grant of exemption if I'm not charging for my services? A. Unless you are flying only for hobby or recreational purposes, you will need FAA authorization via a Section 333 grant of exemption to fly your unmanned aircraft system (UAS) for your business. This applies even if you are only flying to supplement or aide your business and not charging fees for doing so. For now, until there is clarity, I feel I am not legally allowed to test fly customers aircraft without the 333.