SUMMARY OF HEARING: Tuesday, December 9, 1997

Jet fuel tanks, fuel and its flammability came under close scrutiny during the NTSB’s second day of a public hearing into the midair explosion of TWA flight 800, with scientists saying that a major improvement to aviation safety could be made by reducing the temperature in center fuel tanks.

This assessment on ways to improve safety came from a senior NTSB scientist, Dr. Merritt Birky, and Dr. Joseph Shepherd, associate professor of aeronautics at the California Institute of Technology.

They were among the witnesses and experts testifying at the hearings that centered on fuel tank design philosophy and certification and on flammability. The public hearing on Wednesday will begin with an examination of potential ignition sources.

While NTSB investigators have determined that an explosion took place in the 747’s center fuel tank, they have not yet determined what triggered that explosion.

Officials from the FAA and Boeing explained the philosophy used in the design of fuel tanks. They said it was assumed that the air space in a tank was always flammable and they therefore attempt to design out all potential ignition sources.

Senior NTSB scientists outlined the characteristics of jet fuel – including the conditions needed for it to explode – and then described a series of flight tests they conducted to try to determine what conditions existed at the time of the explosion and also to explore possible solutions.