This advisory circular (AC) provides general guidance for acceptable means, but not the only means, of demonstrating compliance with those provisions of title 14, Code of Federal Regulations (14 CFR) 25.629, Aeroelastic stability requirements, and other part 25 regulations related to aeroelastic instabilities of flutter, divergence, and control reversal. Revision C would incorporate changes to portions of this AC affected by the System Safety Assessments proposed rulemaking, Notice No. FAA-2022-1544, which would revise the failure criteria specified in §§ 25.629, 25.671, and 25.1309.

This order defines the policy and procedures for the National Kit Evaluation Team (NKET)
and establishes a standard methodology to evaluate amateur-built aircraft kits. It also describes the
selection and orientation of team members, the process for requesting an aircraft kit evaluation,
the conduct of evaluations, and the reporting and records maintenance requirements.

This Order modifies and establishes certain issue resolution and
appeal processes related to type certification activities.

This AC describes acceptable means for showing compliance with the requirements of
Title 14, Code of Federal Regulations (14 CFR) 25.353, Rudder control reversal
conditions, at amendment 25-147. Section 25.353 requires that transport category
airplanes be designed to withstand the structural load conditions that result from at least
three cyclic, full rudder pedal reversals, if those airplanes have a powered rudder
control surface or surfaces.The contents of this document do not have the force and effect of law and are not meant
to bind the public in any way. This document is intended only to provide clarity to the
public regarding existing requirements under the law or agency policies.