21st Congress of International Council of the Aeronautical Sciences, Melbourne, Australia, 13-18 September, 1998
Paper ICAS-98-4.2.1

CRASH BEHAVIOUR OF HELICOPTER FUEL TANK STRUCTURES

Anghileri M.
Milan Polytechnical University, Italy

Keywords: crash behaviou, helicopter fuel tank structures

Object of the present work is the study, by means of experimental testing and numerical simulations, of the crashworthiness characteristics of an helicopter fuel tank. A good design of fuel tanks is essential in preventing dangerous injuries in crash landings; most of those injuries are in fact caused by fire generated by fuel leakage after the impact. While good results have been obtained in reducing accelerations expert by passengers during impacts improving seats and restraints systems, extensive effort are still required in order to reduce fire hazard in crash landings. Finite element codes are now available to better understand the dynamics involved in these phenomenon. For this reason a first activity has been conducted using experiments and simulations to deeply investigate the problems connected with the crash worthiness of fuel tank. This first phase was conducted on simple structures representative of real fuel tanks: size, materials and shapes were maintained comparable with those used in helicopters components. Finite element gave reliable results regarding the global behaviour of the structure and the movement of the fluid inside the tank. Problems are still present regarding the simulation of rivets used to joint the specimens. After this first phase the second part of the work was faced with a real fuel tank extracted from an Agusta helicopter. Preliminary simulations were conducted to obtain indications on the results of the experimental test. Existing regulations ask for fuel systems crash resistance to be verified with static tests and a final drop test. The prescribed static tests are of arduous realisation mainly due to the difficulty of representing fluid dynamic loads acting on to the tank structure. The work is finally trying to propose a new kind of testing for helicopter tanks by means of dynamic tests similar to those prescribed for other aircraft structure (i.e. seats).

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