FAA AC 27-1B:2018

(1) The objective of this MG is to provide guidance regarding the regulatory HF components that should be considered during a certification project for rotorcraft. While applicants are the main target audience, this guidance can be used by all FAA project team members including:(i) Aircraft Evaluation Group (AEG) inspectors, (ii) avionics engineers, (iii) project managers, (iv) flight test pilots and engineers, (v) HF specialists and engineers, (vi) propulsion engineers, and (vii) systems engineers. (2) This MG is general and high level, covering the HF aspects of certificating a rotorcraft or system installation on a new or previously-certificated normal category rotorcraft. It is intended to guide applicants and certification engineers on what they should consider regarding HF during project planning and execution