Pilot Of TWA 800 Just Before Fateful Flight Questions Official Conclusions
Associated Retired Aviation Professionals
Post Office Box 90, Clements, Maryland 20624 USA
It is no surprise to anyone on either side of the TWA Flight 800 controversy that the National Transportation Safety Board declared at its final, just concluded hearing that the doomed plane that exploded four summers ago was brought down by an electrical spark which had ignited vapors in the empty or near empty center wing fuel tank.
Unfortunately, the NTSB said, its investigators have not been able to locate the spark or wire that originated the explosion.
Among the many who contest the NTSB scenario is the last pilot to fly the 747 and live to talk about it.
In a phone interview some days after the NTSB hearing, now retired TWA pilot Al Mundo, who had brought the plane into New York from Athens late on the afternoon of July 17, 1996, explained not only the fuel system of the plane, but detailed his reasons why the center wing fuel tank would not have been the initiating cause of the explosion or explosions that destroyed Flight 800.
"We had left Athens that Wednesday morning," said Mundo. "The center wing tank would have been full."
The center wing fuel tank is just that: a tank of fuel that is directly in the middle of the plane, beneath the passenger cabin.
Before going into the reasons why the fuel in that tank would not have been full on arrival in New York, Mundo explained the fuel system of the 747.
"There are four main tanks of fuel, and two reserve tanks, to feed into four engines. If you're sitting in the cockpit, from left to right, you have on the edge of the left wing, the number one reserve tank. Then, in sequence, you have the number one main tank, number two main tank, number three main tank, number four main tank, then on the tip of the right wing, the number four reserve tank."
Mundo went on to say that the fuel flow of the plane is maintained so that the weight of fuel throughout the wing span will be balanced. Fuel is normally fed from each tank to its corresponding engine, although, said Mundo, when the combined fuel in the number one main tank and its reserve, and the number four main tank and its reserve equals 25,000 pounds (the fuel is measured in pounds, not gallons), cross feeding fuel procedures are initiated.
"We turn on both of the center wing tank fuel pumps. The center wing tank has two pumps, which work at twice the capacity of the other four main tank pumps; their fuel flow is at fifteen pounds per square inch (psi), the center wing tank pumps put out fuel at thirty psi.
"The cross feed valves are open, which allow fuel from the center wing tank pumps to go to the number one, two, three and four engines. We shut off the pumps from the number one main and its reserve and the number four main and its reserve. We leave the pumps on from two and three as back up, though because they are working at a rate only half that of the center wing tank, it's the center wing tank that is supplying fuel to the engines. At that point the two and three main tank feed is there as a backup. Anyway, at this point the center wing tank is supplying fuel to all the engines.
"Eventually, as the center wing tank burns down to about 3,000-4,000 pounds of fuel, the fuel begins to feed from the number two and three main tanks."
When the fuel quantity in the center wing tank gets low, a light for each pump begins to blink on the flight engineer's panels. "When the light gets steady," said Mundo, "you turn off the pump for that light.
"Then you turn on the fuel/water scavenge pumps in the center wing tank to drain any liquid remaining. "
With the feed from the center wing tank now turned off, all four engines are being fueled from the number two and number three main tanks. At the point where there are about 25,000 pounds of fuel in each of the main tanks (again, with number one main and reserve tanks and number four and reserve tanks totalling 25,000 pounds each), so there is an even balance across the wing. Cross feeding is terminated so that main tank one and its reserve will be going into its respective engine, number two into its respective engine and so forth.
Mundo went on: "When the plane landed in New York, the center wing tank guage in the cockpit would have read zero pounds. It is possible that the underwing center wing tank fuel gauge could have read 300 pounds, which would be about fifty gallons. This is not an unusual discrepancy."
In the first few days after the Flight 800 investigation Mundo asked a TWA official what exactly the fuel use log had shown in regards to the quantity of fuel in the center wing tank upon arriving in New York. "He told me," Mundo said, "that the log, which is placed in the Flight Document Envelope and normally kept for ninety days, could not be found. This was an abnormality."
He added that whatever level of fuel existed in the center wing tank at that time would not be entirely composed of fuel. "All fuel contains some water. It's the same with the gas in your car. Fuel is 6.7 pounds per gallon; water is heavier, 8.34 pounds, so the water goes to the bottom of the tank. This combination of water and fuel is what the scavenger pumps transfer to the number two main tank."
Mundo said, "When 747's undergo a heavy maintenance check, and the nose wheel strut is deflated which tilts the plane downward, all the liquid in the center wing tank fuel goes to the front of the tank where it is drained out. The amount drained is usually close to fifty gallons or around 300 pounds."
In sum, the center wing tank of the plane that was about to become Flight 800 was empty or nearly empty before leaving New York in the late afternoon prior to its evening takeoff to Paris.
Because of prevailing winds, planes usually carry more fuel when going west than when going east. "And then," said Mundo, "you also have to consider the distance youâ ¬!"re travelling. Athens to New York is a lot farther than New York to Paris."
Now we get to one of the crucial points of the NTSB theory about the volatility of the center wing tank. Mundo said, "There is the assumption by the NTSB that the fuel was heated by the air conditioning packs below the plane to a temperature that caused the fuel and fuel vapors to reach an explosive level."
This is an assessment with which the majority of the media concur. A New York Times article from Wednesday, August 23, the day after the NTSB hearing began, stated, "the nearly empty tank, which had been heated to an explosive state while the twenty-five year old jet sat baking in the sun for nearly three hours before taking off."
Mundo said, "I left two of the packs running, as was common practice." He added that with the flight time between Athens and New York at about ten hours, "for at least nine and half hours the metal of the tank was, at the altitude we had been flying, exposed to temperatures that were about minus fifty-five degrees Celsius. Now metal will cold soak when your car is outside through the night in January you know it takes the metal some time to warm up.
"This is something they should have tested, but they didn't, exactly. The NTSB flew a plane across the continental United States, trying to duplicate the conditions of the Athens to New York flight, but in the summer the air over the land would be warmer than over the North Atlantic and of course the plane would not be in the air for as long as on an Athens to New York run. Nobody knows exactly what the temperature in the fuel tank was when Flight 800 took off from New York. Commander Donaldson took a reading from a 747 at Kennedy the summer after the accident, and he found the temperature of the fuel drained from the center wing tank which had been on the ground an equivalent amount of time as 800 was, to be a degree above the ambient [outside] tempertaure." (Retired Navy Commander William S. Donaldson has been a longtime critic of the government's investigation of Flight 800.)
"Flight 800 took off for Paris at about 8:15 p.m. on the evening of July 17, 1996. A nearly empty tank has more fuel vapor than a tank that is full. Government investigators speculate that the vapor-ridden center wing full tank was ripe for an explosion instigated by the as-yet unfound electrical source.
But Mundo pointed out that the center wing fuel tank is vented to relieve the pressure inside the tank. "With an aircraft in flight," Mundo said, "you have a Venturi effect over the vent outlet. The more the speed, the less the pressure. When you're in a car and someone's smoking and you open a window, the air pressure outside is less than the pressure inside and the greater pressure inside pushes the air outside; the smoke will be sucked out of the car. The air rushing outside the plane would create a great suction that should have decreased or eliminated any buildup of vapor in the tank." _____
Former TWA pilot Al Mundo then talked about another aspect of the electrical spark theory: on Good Friday, 1995, when he was flying the plane that would become Flight 800 in July, 1996, the aircraft was struck not once but twice by lightning.
The plane did not explode.
"We were descending into Rome. We were at about 13,000-11,000 feet. There were two strikes of lightning, about three minutes apart. There was a loud bang, and a yellow flash; initially there was no indication of anything wrong in the cockpit."
But a photoelectric cell activated an inerting gas whose purpose was to smother any fire or smouldering that could be caused by an electrical spark. This was done on the first lightning strike.
Mundo said, "Upon landing it was discovered there was not only substantial damage to the right wingtip, it was also found that an electrical charge had gone all the way into the wing area, causing circuit breakers in the cockpit to pop and the wheel brake temperature indicators to register full scale when the brakes had scarcely been used. It is quite evident from this that a strong surge of electricty went through the wing.
"The damage incurred was extensive. The plane was out of service for a week," said Mundo.
But despite the damage that had been inflicted by the two lightning strikes, the plane was able to land safely. The inference is obvious: if the plane that expolded fifteen minutes out of JFK in the summer of 1996 was brought down by an electrical spark igniting the center wing fuel tank, why didn't two lightning strikes, which would certainly supply infinitely more voltage to the electrical system of the plane than the theorized stray spark, cause the aircraft to be blown apart?
Early on in the Flight 800 investigation, Mundo learned that there had been sooting found on the right wing vent system. "It seemed strange to me that if the explosion was initiated by the center wing tank, why would there not be sooting on both sides of the wing? I contacted personnel in the investigating team and suggested they check those records from the 1995 flight to determine if the sooting came from the lightning strikes. I was later informed that the records could not be located."
Mundo was questioned by investigators "about five days after Flight 800," he said, but the extent of the questioning was solely on the character of the Athens to New York Flight. The former pilot continues to feel that government investigators have not pursued the obvious lines of inquiry raised above or, if they have, such tests or studies have not been made public.
© 2000 William S. Donaldson III. All rights reserved