Given the number of documented center wing fuel tank explosions in various Boeing aircraft, including cases where wiring was the spark source, your statements are disingenuous.
There has never been a documented case as you describe, particularly using Jet A. There have been several cases using cut fuels (eg, Jet B and JP4), but none with straight kerosine. Boeing does not have a history of CWT explosions. Furthermore, despite what most here seem to believe, the issue wasnt voltage in the CWT, but reportedly use of the CWT fuel boost pump. The tank did not simply explode, and very detailed, expensive efforts to duplicate the explosion were an utter failure. In fact, in order to produce the explosions that were finally demonstrated in the tank mockup tests, after multiple failures, a special ignition system had to be developed and the tank flooded with propane. None of the investigators or agencies involved were able to duplicate the scenario described.
The fact that the aircraft survivability folks at China Lake and Wright-Patt were able to duplicate both the conditions and the results is even more compelling.
Not really. No such duplication ever took place.
Further, the fact that no MANPAD in the world could hit that plane where it was makes any such assertion ludicrous.
Actually, it can. The CWT is adjacent to the pack outlets, which are the primary heat source from a lower shot aspect, such as a Vanguard or Mistral fired from a boat, below.
The truth is such explosions had been happening in similar Boeing designs for years, but due to various parameters being a bit off optimal, the results had not been as catastrophic (although deaths had occurred, notably in a maintenance-related B-52 accident on the ground at IIRC McConnell AFB in Wichta). It was only a matter of time before all the stars came into alignment and a catastrophic in-flight event occurred. You roll the dice long enough, and eventually you hit snake-eyes.
Actually, that's not the truth, and the 747 in question wasn't fueled with cut fuels, and had no reason to use the CWT override boost pumps. There have been no "similar explosions."
The only way to guarantee not losing at this game is not to roll the dice at all, and that's the recommendation we in the combat aircraft survivability business made to the commercial aviation industry -- inert or foam the tanks, because sometimes there will be an explosive mixture, and sometimes a spark will occur, and eventually they'll both happen at once as they did in TW800, among other incidents both in the US and internationally, like the 737 that blew up at the gate in Manila a few years before TW800, and which was conclusively shown to have been sparked by frayed wiring in the center wing fuel tank.
The Philipines Airlines 737 which you reference was not using straight kerosine, but was using cut fuel. Additionally, the issue, and the subsequent AD issued to cover it, with TWA 800 (and the B747 Classic) was with the use of the fuel boost pumps. It had nothing to do with pack operation or proximity of the packs to the fuel tank, and there is still no limitation regarding pack operation when the CWT is full or empty.
In total, there have been something like 50 fuel tank explosions in the past 60 years, but to relate those to TWA 800 is much like saying that your car is dangerous because a lot of others have crashed. Without common causality, there is no valid reason to connect them.
I will say that we run packs nearly all the time in the desert, with very little fuel in the CWT, and have zero problems. Neither the FAA, nor the NTSB ever considered it a problem, which is why there are no limitations regarding pack operation in high temperatures (or otherwise) on the ground, regardless of how much fuel in in the CWT.
Of course, the airlines refused to accept the associated cost and weight penalties of fuel tank ullage explosion protection systems, so the crap game continues. At least they now know what conditions are most conducive to explosivity, and they have put in place procedures to minimize the risk of those conditions occurring, but all they did was reduce the odds, not eliminate the problem.
As for there sometimes being a spark, there's nothing to spark in the CWT, as there are no live voltages in there. There's no wiring which might spark, either. Additionally, in every effort to duplicate the CWT explosion, sparks in the tank were unable to ignite the tank, until a mixture was introduced into the tank which is not ever found in operation or in the aircraft, and even then it was only introduced to create an explosion for effect. The test tank could not be blown up, otherwise. The testing agencies were 100% unsuccessful in creating an explosion using anything found in the aircraft, and they failed repeatedly when putting ignitors and other devices in the tank that aren't found in the aircraft.
As I said, I'm not going to enter into an argument about it; anyone associated with the aircraft or who operates it regularly with whom I'm familiar, from mechanics to crew, don't believe that it was a simply CWT explosion as the NTSB (et al) suggests. Nobody.
The CWT AD, and the "fix" for the problem that was never actually found, is that if any fuel is to be used from the CWT, it must contain at least 17,000 lbs. That is, if one intends to use 1,000 lbs of fuel in the CWT, then it must be filled with 17,000 lbs, and the reason is to cover the boost pumps. If more than 50,000 lbs of fuel is put in the CWT, then it can be burned down to 3,000 lbs, and the remainder removed with a scavenge pump. If less than 50,000 lbs is in the tank, it can be burned down to 7,000 in the climb, then down to 3,000 in level flight, and the remainder scavenged.
Again, the point is to keep the boost pumps submerged. The reasoning behind the AD is to prevent the pump impellers from overspeeding, overheating the bearings, and causing damage.
The fuel Quantity Indication System (FQIS) was addressed repeatedly, but as it contains no live voltage and works simply off capacitance and comparative values, and because the original system is still in use as part of three different FQIS systems found in the Classic 747, it's not the culprit, and could never have been the culprit. Despite having been tagged as part of the issue, there's nothing a "frayed wire" could do to duplicate what's been suggested, and nobody was ever able to locate such wiring or show it to be the case.
The CWT in the Classic holds more fuel in weight than a fully loaded DC9. It's seldom used; it's not used unless the main fuel load exceeds 230,000 lbs, which is the standard max wing fuel load with the main fuel tanks and aux tanks full. A transatlantic flight such as TWA 800 took didn't require CWT fuel; normally only a small amount remains in the CWT, and this would only present a hazard if the CWT override boost pumps were left on continuously. these pumps, in the middle of the fuel module on the FE panel, aren't turned on except under certain circumstances (dedicated CWT fuel feed configuration or a jettison situation), and display a bright amber LOW PRESS indication for each pump if turned on when insufficient fuel is available to pump (less than approx. 3000 lbs in the CWT). These aren't switches that simply get left on inadvertently, and they're also part of the interior cockpit safety inspection that's first done upon arriving at the airplane.
Use of the CWT override boost pumps wouldn't have been part of the takeoff or climb fuel feed configurations in use in TWA 800, for a number of reasons. It's unreasonable, in fact, to suggest that fuel would have been in use or pumps would have been in use in that tank during that phase of flight.
I regularly operate the B747 into Afghanistan and other sensitive locations. I'm aware of a few crews of FE's that prefer to shut off the packs to reduce the heat signature during the final approach phases of the flight, but I don't require that, and don't see the need. It is the most likely source, however, for a MANPAD or other shot from an aspect beneath the aircraft, or for any heat seeking surface to air shot.