Manufacturing and Maintenance Operations for Bladder-Type Aircraft Fuel Tanks

Abstract

The airplanes’ fuselage and their equipment are specified for challenging conditions. They carry a huge amount of fluids such as fuel, hydraulics, conditioned gases, etc. While these state-of-art machines are flying, the mentioned fluids transfer through the body maintaining flight stability. Besides transferring, the weight of the fuel changes during flight depending on the characteristics of the relevant flight stages. During the takeoff and climb stage, the aircraft consumes more fuel than the cruise and descent stages of a regular flight. Out of question, if the aircraft has vertical takeoff capability the consumed fuel will be more than the similar airplanes that use the runway for departure. As a matter of fact, the weight change of the fuel is a crucial issue that must be monitored by pilots during the flight path. No sudden changes are wanted since they have direct impacts on the Center of Gravity (cg) of the aircraft. To prevent these unwanted changes, many state-of-art techniques have been implemented in aircraft fuel tanks. Another important feature for fuel tanks is crashworthiness. The “fuel-tank crashworthiness” can be defined as “the ability of the fuel-tank structure to protect the fuel inside and therefore retard any possible fire after crash.” Obviously, aircraft parts are generally made of fire-proof material but the fuel system, itself needs more meticulous measurements than the other airborne components since it contains highly flammable substances as a necessity of its task. In this chapter, the types of fuel tanks are examined while focusing on the bladder ones since they have increased attention with the improvement of novel materials such as carbon fibers and retardant chemicals. These materials are used for manufacturing the skin of the bladder fuel tank while the fuel-resistant sponge fills the inside the tank for preventing the slosh and hence the stick-lateness phenomena which is another unwanted issue by pilots. Besides, bladder fuel tanks are far lighter than the other types of fuel tanks with close fuel capacity. With the lightweight feature, they have a direct positive effect for decreasing the direct operational cost (DOC) since even 1 (one) kg of weight reduction is important for airliners because of the fierce competition in the aviation industry. From the follow-on-support side, any fuel-system maintenance staff wants a fuel tank that is foldable and easy to remove and replace. The vacuum ability feature of the bladder fuel tanks provides solutions to maintenance staff for making easy repair and easy maintenance operations. It is even possible to make brush-up repairs from maintenance doors. Eventually, the bladder-type aircraft fuel tanks will be used more widely in the future with their splendid features.KeywordsAircraft fuel systemAircraft fuel tanksBladder-type fuel tanks