Which part of FAR primarily addresses large aircraft standards?

FAR part 25 primarily addresses the airworthiness standards for transport category airplanes, which include large aircraft. This part is crucial as it outlines the design and performance requirements that must be met for commercial aircraft, ensuring safety and reliability during operation. It covers a variety of essential aspects such as structural integrity, performance, and operational limitations.

In contrast, FAR part 23 pertains to small aircraft and sets standards for lighter planes, while FAR part 27 and FAR part 29 are focused on the airworthiness standards for rotorcraft and transport category rotorcraft, respectively. Therefore, when discussing large aircraft standards specifically, FAR part 25 is the relevant regulation that comprehensively outlines the necessary criteria for ensuring that these aircraft are safe for flight operations.