Which regulation outlines airworthiness standards for airplanes in the normal category with specific seating configurations?

The regulation that outlines airworthiness standards for airplanes in the normal category, particularly focusing on specific seating configurations, is indeed 14 CFR Part 23. This part specifies the requirements for small aircraft, primarily designed for the normal, utility, and acrobatic categories.

Part 23 includes standards addressing aspects such as structural integrity, performance, and safety features that are crucial for assuring that the aircraft can operate safely within its designated limits. The reference to "normal category" is particularly important as it stresses the design criteria formulated for the general aviation planes typically used for non-commercial purposes, emphasizing passenger safety based on the seating capacity and configurations allowed.

By recognizing the unique regulations under Part 23, aviation professionals can ensure that they meet the necessary airworthiness requirements for the specific types of aircraft they work with in the normal category.