As a DER we act as the interface between the client or applicant and the FAA. So a good working relationship is always good to ensure that there is a level of trust between the client and the DER. The DER may also call in other DERs when appropriate to help suport a project. For example a project may have both electrical features as well as mechanical features which need to be addressed so both DERs would provide guidance and approval for their specific data ratings. The DER works hand in hand with the applicant to make sure he understands the project and the end result the customer is seeking or can advise what other ramifications may have to be addressed to be able to obtain final certification.