I'm an aerospace engineer and I work in certification. This is par the course. The regulatory authority allows delegates to make findings of conformance w.r.t. airworthiness standards for aeronautical products. These delegated engineers have narrow specialties and are delegated for only specific ATA chapters or subsections. So Boeing will have a few delegated engineers whose only job is to certify Chapter 28 'Fuel Systems' components. These delegated engineers act as 'Design Approval Representatives' (DARs). They do this through something called an 'Organization Designation Authorization' (ODA). This is the regulators way of allowing some trusted individuals to make decisions on behalf of the regulator. This is often because these engineers are experts in their fields so they take on full responsibility. It's the equivalent of an engineers 'stamp' in civil engineering.