Problems in designing fuel installation for small turboprop aircraft

Abstract

This paper discusses the problems of designing a fuel installation for the I-31T, four seat, fully composite aircraft designed in accordance with FAR 23/CS 23. The project was carried out under the European Union project entitled ESPOSA (7th Frame Programme)—“Efficient Systems and Propulsion for Small Aircraft”. I-31 Turbo has been created on the base frame of the I-23 “Manager” aircraft, through replacement of its original piston engine, the Lycoming O-360 A1A, with a TP-100 turbo shaft engine. Moreover, the front of the plane, from the bulkhead 1, was altered, while the old navigation and piloting equipment was substituted with a modern “glass cockpit”. These modifications required designing of a new fuel system within the engine chamber. The existing fuel system in the fuselage and wings was adapted for the new JET-A fuel. In order to confirm whether the installation in the wings and the fuselage would provide the consumption rate required by the TP-100 engine (a tripling of the fuel flow and a ten-fold increase in kinematic viscosity of fuel), calculations and simulations were carried out. The calculations were verified using the second I-23 aircraft, designated for static campaign tests. The ground tests studied the flow of the fuel from the auxiliary tank and were carried out under two different fuel temperatures (−20 ℃ and 20 ℃) and two different fuselage angles (0 and −10.7°). The project was documented in 3D in CATIA V5 program and in project documentation. To sum up, the main innovative element of the fuel system in the engine chamber is the module containing the pumps, filters, one-way valves, flow meter, among others. This concentration of parts allows a significant reduction in plane servicing time in between flights.