From: "P. Wezeman" <email@example.com> Organization: The University of Iowa Date: Tue, 22 Oct 1996 23:48:53 GMT Followups: 1 2 3 4 5 6
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I would like to thank everyone who answered my question about the use of inert (non oxygen containing) gasses in the ullage spaces in aircraft fuel tanks to prevent fuel-air explosions. This question is naturally related to the loss of TWA flight 800, where investigators have been reported to have found evidence consistent with such an explosion in the center fuel tank. To summarize the information I received, many aircraft have successfully used inert gas systems. In particular, the C-5 and C-17 transports flown by the United States Air Force use nitrogen gas for this purpose. The newer of these two aircraft, the C-17, has a device that separates ambient air into its two main constituents, oxygen and nitrogen, and sends the nitrogen produced to the fuel tanks. As I understand it, this is the same basic process that has been used on other aircraft to produce breathing oxygen for the crew. Military air transport does not, of course, have exactly the same economic constraints as an airline, but still the C-17 is similar to a large airliner in several respects, including size, type of engines and number of flight crew (excluding cabin attendants), and the C-17 is said to have been designed to strict specifications of total lifetime cost, including maintenance. McDonnell Douglas in fact is currently offering the C-17 for sale to commercial operators, although the civilian version will lack the on board inert gas generating system as well as in-flight refueling equipment and some other systems. Is there any reason that it would be impractical to put a nitrogen fuel tank pressurization system similar to that on the C-17 on an airliner? Could it be retrofitted, or would it have to be incorporated in new models only? Aside from the weight and space, I can't see any drawbacks, in that the failure of such a system would not in itself endanger the aircraft. Ambient air would still be available for venting, so it would be no more dangerous than present practice, as long as maintenance on the electrical system was kept to the current standard. Thank you in anticipation, Peter Wezeman, anti-social Darwinist "Carpe Cyprinidae"