discovery of frayed wire to gauge is cited at crash hearing
1997 federal security investigators said today that they found a worn-out wire on a fuel meter in the fuel tank of Trans-World Airlines Flight 800, guiding them to find the way to wire--
Combine other questions-
It could have been an explosion that killed 230 people in July 1996.
They say the faulty wire can\'t cause a crash alone, because it usually has less power than it needs to generate a spark.
But they said they were investigating whether the fuel tank wiring problem was part of a series of failures that caused the accident.
On the third day of the hearing that the Boeing 747 crashed on Long Island, investigators explored various possible sources of ignition, and went deep into the fuel tank problems that Boeing and the Federal Aviation Administration said were largely undiscovered before the crash.
One of them is the storage tank wiring corrosion caused by sulfur in the fuel.
The chemical deposits formed around the meter can provide the heat needed for the explosion, if subject to a surge in power.
But it is not clear where the surge will come from;
Investigators said today that some of the lines that may be the problem have been found to be in good condition and some have not been found at all.
A long-term theory is that there is a shortage of electricity.
The circuit elsewhere on the plane sends a surge of power to a place that should be low.
Although Boeing believes there is not enough voltage system on board.
Advertising line damage and corrosion deposits can constitute \"potential faults\", or undiscovered faults for months or years, which are not important until they are combined to cause an accident in an abnormal situation.
They also represent a huge expansion by government regulators over aircraft aging.
So far, the problem of ensuring that aging aircraft are still worth flying is mainly limited to their metal shells and bones;
Now it extends like a wire to their internal organs.
Investigators are concerned about corrosion and line damage, in part because of the early theory that static electricity has accumulated in the tank and has so far been unable to prove it in the laboratory.
According to a witness today, the corrosion problem in the fuel tank of the aircraft was initially discovered by the Air Force in 1990, in the form of a chemical stripe inside the tank.
F. Expert in fuel systemsA. A.
Christopher Hartonas said his agency was not aware of such deposits until the investigation of the accident, but they did raise some safety concerns as potential ignition sites.
He said that a recent proposed rule change by the agency would address the issue of installing surge protectors in lines leading to tanks.
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Boeing, which advised its customers earlier this year to check their central fuel tank, said today it will revise the proposal soon to check the end blocks that use copper and silver and may have such deposits.
According to a suggestion previously known as a service announcement, 52 of some 970 Boeing 747 have been inspected.
It is not clear whether these must be re-established.
Boeing said it had checked.
In addition, Boeing said publicly on Tuesday for the first time that it was looking at how to reduce the explosion of the atmosphere inside the tank, and disclosed today that it was experimenting with a \"flame storm\", even if the sewage pump was on fire, tanks can also be protected.
Cleaning pump, a low
With the exception of the last few gallons, the capacity pump to empty all gallons from the central tank was the suspect of Flight 800 crash, in part because it was never found.
Ivor Thomas, a Boeing fuel system expert, testified that Boeing is testing such a lightning arrester \"even when we speak\" to \"protect the removal pump itself from some strange ignition sources
\"Advertising Boeing engineers are\" going beyond what we do, \"he said \".
Aviation experts have shown mixed feelings about strengthening inspections of central tanks.
Boeing and F. A. A.
It is said that sending workers into such tanks is difficult for workers and will cause additional problems in tanks.
As a participant in the hearing, Fred Riddle, a mechanic representing the International Association of mechanics and Aerospace Workers, discussed the issue.
Although the center tank on 747 is two-car garage --
The ceiling is under 6 feet--
It is divided into many smaller rooms.
\"If you have claustrophobic people, you will get that,\" he said . \"
Riddle who works for T. W. A.
\"You can damage it if you can\'t see anything, you can hit it with your feet, and you don\'t even know that you \'ve damaged it.
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A version of the article was published on page B00006 of the National edition on December 11, 1997, with the title: a wire found to wear was quoted at the collision hearing for measurement.