TWA 800: Persecution by Prosecution

American Thinker ^ | July 3, 2016 | James D. Sanders

[Drago]

I notice 4 divisions there, dividing the tank into 5 sections. Are those some sort of walls or support beams or what?

Yes, fuel tanks on large jet aircraft are "integral" fuel tanks (part of the AC structure), those "dividers" are sealed beams and spars that make up part of the AC structure AND the tank.

[Moonman62]

Nice pictures in #165 and #166, but I wonder why they are invisible to some people.

[Swordmaker]

That "compensator" at the bottom of the probe is a capacitance device which generates its own current which is sent through those wires, one of which is a grounding wire. It is essentially the same as your finger touching your capacitance touch screen on your smartphone.

"The fuel compensator probe (hereafter referred to as the compensator) is a component of the Boeing 747 Fuel Quantity Indication System (FQIS). This system uses submerged fuel probes that convert voltage capacitance to the volume of fuel within the aircraft’s fuel tanks. The compensator is used to adjust, or compensate, the fuel probe’s readings for fuel capacitance variations caused by variations in fuel temperature . Within the B-747 CWT, there is one compensator." — FAA report on FQIS from Boeing 747 wreckage for TWA-800

The main sensors for the fuel capacity are in the tube it is attached to right next to it. Those wires are connected above the tank.

These very low voltage/amperage compensator sensor wires are the only wires in the 747 Center Wing Tank. . . and there in only one of these connected to one fuel probe. There are no other wires running into or through the fuel tanks on a 747.

By the way, thanks for the research.

[UCANSEE2]

OK. Why is there a hole on the other side of the fuselage ?

The side they don't normally show in these photos ?

[Drago]

Now that we have established that there are wires in the 747 center tank, let's look at where the low-voltage FQIS wires run (especially in relation to 115vac "FFIS" [fuel flow indicating system]) wires. What I find very interesting is that the captain says "Look at that crazy fuel flow indicator there on number four." at 2029: 15 (CAM- 1)...and TWA-880 explodes 90 seconds later (2031:03):

Interesting, yes?

https://app.ntsb.gov/foia/twa800/FOI96MA070E/369639.pdf
http://www.ntsb.gov/investigations/AccidentReports/Reports/AAR0003_app.pdf
https://sma.nasa.gov/docs/default-source/safety-messages/safetymessage-2011-01-09-twa800inflightbreakup-vits.pdf

[Drago]

BTW: it is a LARGE fuel tank:

[angryoldfatman]

The past few exchanges is why I love FreeRepublic, guys. This is what I think it should be all about. We’re not leftists yelling talking points at each other, we’re reasonable men and women having a discussion with actual information and data.

[angryoldfatman]

Nice pictures in #165 and #166, but I wonder why they are invisible to some people.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Not me.

http://www.freerepublic.com/focus/news/3446012/posts?page=174#174

[GBA]

What does the low voltage/amperage compensator sensor in the tank talk to?

Often such low currents and voltage devices have to talk to a device, perhaps an analog to digital converter/multiplexer of some sort, that collects, converts and then sends that info on down/up stream to something else.

If that's the case here, then the crazy fuel flow the pilot saw on the indicator for number 4 could have been that channel going bad on "something somewhere" well away from the tank itself.

A fraying wire often leaves clues that it's having a problem.

I wonder if the previous crew or other crews had seen it, too, and maybe had written it up.

[Moonman62]

I wonder if the previous crew or other crews had seen it, too, and maybe had written it up.

...

It was written up and serviced in May, 1996.

[Moonman62]

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The relevant section from the NTSB report. The power harmonics dropouts, and incorrect indication on the fuel gauge are also evidence that the initiating event was electrical.