Read the quoted story below and you might begin to appreciate that they have known all along what caused TWA800 to explode. When you have read all that was known (below) and then (right-click "save as..") downloaded and viewed the colour photos from the parent pdf (acrobat) file at
this link, you will appreciate that:
a. silver-soldered terminal connections interact with the sulfur in JetA fuel to form conductive silver-sulfide deposits. The accumulation of these electrically conductive deposits on fuel tank FQIS terminal blocks means that there is a breakdown in that terminal block's insulation and as little as a 9 volt transistor radio battery can cause an arc across that FQIS terminal block. So we might conclude that not a lot of misdirected electricity was required to ignite that centre wing tank of TWA800 (or the 737's in Manila and Bangkok). The aging wire and a minor amount of induced current was all that was required to arc across the FQIS terminal block.
b. Smiths Industries and many other responsible manufacturers of intank electrics have been very
quietly changing over to nickel-plated terminations on wiring, hoping that this nasty problem will just "go away".
c. The FAA has decided that a quiet program with the cooperation of the relevant sections of industry is in everybody's best interests. It would, after all, be a huge program to swap out all immersed silver-soldered wiring in fuel-tanks, wouldn't it?
Boeing Analytical Engineenng Report 2-5323-WP-91-97, dated March 10, 1991. that described Boeing's examination of sulfide deposit, on a harness from a fuel quantity indicator from the right wing tank of a 757, The fuel quantity indicator had a documented history of iregularities after only 750 hours in service. The report noted "it is readily observed that the contaminant has migrated up into the conductor even after only 750 hours in service".
Boeing Laboratory Report 9-5576-P+CA-025P, dated March 30, 1993, that described sulfide deposits on electrical hardware from the fuel tanks of 737, 747, and DC-10 airplanes.
Boeing Laboratory Report 95576-P+CA-025P1, dated April 29, 1993, that also described sulfide deposits on electrical hardware from the fuel tanks of 737, 747 and DC-1O airplanes and included two additional reports obtained through a literature search): Silver Corrosion by aviation Turbine Fuel , dated September 1970. written at the Journal of the Institute of Petroleum; and Copper and Silver Corrosion by Aviation Turbine Fuels, dated April 22, 1973 written at the Indian Instituteof Petroleum.
Boeing Analytical Engineering Report 9-5576-WP-97-272, dated August 5th 1997, that described electrical tests of FQIS parts containing sulfide deposits.
During FAA-sponsored tests conducted in response to Safety Recommendation A-98-37 (issued as a result of this accident) researchers at the University of Arizona also used the method developed by UDRI to create silver-sulfide deposits in a laboratory. During subsequent tests, these deposits served as an ignition mechanism for Jet A fuel vapor. The results of these tests were discussed at a November 9, 1999 meeting involving FAA, Safety Board. and industry personnel. According to University of Arizona personnel, the formation of sulfur-containing conductive deposits from Jet A fuel on silver wire occurred with both a.c. and d.c. current Additional tests in this area are ongoing".
In response to AFRL's findings from the 1990 vapor ignition incident. BFGoodrich eliminated the use of silver-plated components in the FQIS and began using nickel-plated wire, gold-plated ring connectors, and sealant Those improved components have been used in military airplanes since about 1993. According to BFGoodrich, since that time there has been a large reduction in the FQIS anomalies that had associated with silver sulfate deposits (such as FQIS innacuracies. Although a Boeing 1991 engineering report indicated that silver should never contact sulfur-containing liquids because of the susceptibility to sulfidation, and Boeing uses nickel-plated (instead of silver-plated) wiring in its newly manufactured 777 and 737-NG airplanes, Boeing indicated in a December 7, 1999, letter to the Safety Board that it does not recommend replacing silver-plated FQIS components in existing airplanes.