Research on Verification Method for Unusable Fuel Quantity Compliance of Civil Aircraft

Abstract

In civil transport aircraft, due to the structural characteristics of the fuel tank, fuel pipelines, and fuel pump layout, a certain amount of fuel in the fuel tank cannot be delivered to the engine by the fuel pump. This part of the fuel is known as unusable fuel. This article mainly refers to CCAR25 [1] requirements and the airworthiness certification practices of domestic and foreign models. It analyzes the technical requirements of the airworthiness clause regarding unusable fuel quantity from aspects such as design and verification requirements, the scheduled operation and maneuver flight of the aircraft, the most unfavorable fuel supply conditions, and the criteria for abnormal engine operation. According to the analysis of the requirements of airworthiness regulations, this article also presents the proposed airworthiness compliance verification methods and analyzes the technical key points of MC1, MC2, MC5 and MC6 airworthiness compliance verification methods, providing references for the airworthiness compliance verification of civil aircraft unusable fuel.