A brief description of the Technical Paper;

Aircraft development efforts are rapidly shifting toward the use of hybrid energy systems employing novel airframe and propulsion designs that do not neatly fit within existing certification categories.  This creates challenges in defining a path to certification for subsystems, such as fuel measurement, that have historically had different requirements based on aircraft type.  This paper provides a roadmap through existing regulations specific to fuel measurement systems, with a thorough examination of 14 CFR Parts 23, 25, 27, and 29, to compare and contrast the requirements between each to help aircraft designers determine the best harmonization of those requirements for their particular hybrid aircraft design. In addition, factors impacting accuracy in fuel measurement are discussed, demonstrating how a systems approach, focusing on a well-integrated subsystem, can improve accuracy.