What are the main certification regulations for aircraft?

Key certification regulations: FAR Part 25 / CS-25 - Transport category aircraft (>19 passengers or >19,000 lb MTOW); FAR Part 23 / CS-23 - Normal, utility, acrobatic, and commuter aircraft (recent revision simplified structure); FAR Part 27/29 / CS-27/29 - Rotorcraft (normal and transport category); FAR Part 33 / CS-E - Engines; FAR Part 35 / CS-P - Propellers. Certification process: Type Certificate (TC) - Approval for aircraft type design; Production Certificate (PC) - Approval for manufacturing; Airworthiness Certificate (AWC) - Individual aircraft approval. Requirements cover: Flight (performance, handling qualities), Structure (loads, fatigue, damage tolerance), Systems (reliability, failure effects), and Powerplant. Compliance shown through analysis, test (ground and flight), and inspection. FAA issues TC in US, EASA in Europe, with reciprocal recognition agreements.