Investigators of the deadly crash of TWA Flight 800 believe the design of the Boeing 747 aircraft and its fuel tanks were at least partly to blame for the tragedy.
They also cite government certification of the safety of the plane and the tanks, sources familiar with the investigation of the crash.
Investigators, on the first day of a two-day NTSB hearing on the crash, Tuesday said an electrical short circuit outside the center fuel tank of Flight 800 likely sent excess voltage through wires into the tank, igniting flammable vapors and causing the jet to explode.
The jet fell, in flaming pieces, into the Atlantic Ocean near New York shortly after taking off from John F. Kennedy airport more than four years ago. All 230 passengers and crew were killed.
The spark most likely occurred in a high-voltage wire outside the tank, investigators believe. They also think the wire short-circuited and the spark then jumped to a low-voltage wire that runs into the fuel tank.
In addition, the investigators believe the design of the jet is in part to blame. They believe placement of air conditioning units under the fuel tank generated heat that led to vapors in the fuel tank being explosive when touched off by the spark, the sources said.
Unanimous Board Approval Today, on the final day of the hearing, NTSB investigators presented their findings, and the five-member NTSB board unanimously agreed with their conclusion that the wing center fuel tank exploded most likely from a short circuit in the wiring outside the tank. The short-circuit then traveled into the tank through low-voltage wires and ignited the flammable vapors, investigators concluded.
The NTSB board also sided with investigators citing design and certification of fuel tanks as a contributing factor to the accident. The board criticized the design philosophy that assumes aircraft fuel tanks will always contain at least some explosive material and approved a series of recommendations for government regulators and airplane manufacturers.
These recommendations include: A massive review of wiring systems on all airplanes to ensure wires for critical systems are adequately protected Better bonding of components in the fuel tank Reducing the sulfite deposits on components of the fuel tank. Sulfite deposits can mix with metals in certain wires and lead to flammability That the FAA seriously address its own review of how to improve safety of systems on aging aircraft.
Boeing Stands By Design Boeing officials Tuesday stood by the aircraft design.
“The design with the air conditioning packs under the center wing tank is a very common design for Boeing and other manufacturers. It is fully certified by the FAA,” Russ Young, a Boeing spokesman, told ABCNEWS.
Both Boeing and the Federal Aviation Administration, which certifies plane and part safety and design, have long held to the philosophy that to prevent explosions, jets had to eliminate ignition sources, but not necessarily tank flammability.
Another Boeing official told ABCNEWS that reduction of ignition sources and flammability went hand-in-hand.
“We think that both ignition source reduction and flammability reduction are really complementary and not mutually exclusive,” said Ron Hinderberger, director of airplane safety for Boeing. “We think that both of them are needed in order to ensure that we can have the most safe system that we can possibly have.”