Raiders of the lost arc; how to shoot down an F-16 with a BB gun.

• Author: Jones, Stan

In 1984, a naval engineer in Norfolk, Virginia, conducted a crude and improbable experiment. In his backyard, he took a handful of electrical wires, strapped them to a piece of metal, energized them with current, and fired BBs at them. The test, while amateurish, had a serious military purpose. The engineer wanted to know if wires like those that make up the delicate nervous system of a U.S. fighter plane could withstand a barrage of enemy gunfire.

It was a sure bet that the enemy wouldn't be using BBs in a dogfight. But BBswere all it took in Norfolk. The tiny pellets, fired ftom a Daisy air rifle, produced the electrical equivalent of a nervous breakdown. The wires seemed to explode.

The implications of that 1984 experiment began to crystallize a year later, when the tests moved from the back lot to the laboratory and BBs were replaced by .30 caliber bullets. At the Naval Research Laboratory in Washington D.C. and the Naval Air Test Center in Patuxent River, Maryland, technicians found that although one wire type would erupt in a fireworks display of sparks and flame when fired upon, two other types would not. But that was little consolation for the Navy. Kapton, the type of wire used most often in the Navy's hottest frontline fighters-and those of the other service branches as well-was the one given to pyrotechnics.

The Navy's tests are no small matter. Although key components of military aircraft, such as engines, fuel cells, and sophisticated onboard computers, have long been built with an eye toward surviving combat, the electrical wiring that links them has not. Under fire, Kapton wiring is an Achilles' heel in the military's most sop]isticated flying fortresses. A single bullet holds the potential to cripple, or even doom, the nation's most formidable fighting aircraft,

And it might not even take a bullet. For reasons still not fully understood, Kapton wires sometimes explode under the routine stress of peacetime flight. Though no deaths have been traced to the wiring, military documents obtained under the Freedom of Information Act show that it has become a suspect in a rash of inflight fires aboard both military and commercial planes as well as aboard the space shuttle Columbia. Exploding wires are listed as a possible factor in the crash of a navy jet in 1986 and in at least a dozen other cases in which military aircraft have faced a power loss or fire but managed to land safely. More than 100 other aircraft wire fires, both on and off the ground, have occurred under circumstances that bear striking similarities, military records suggest, but hard evidence to link them to Kapton is lacking.

The Navy has banned Kapton in new planes and in repairs to existing ones. The Army is moving toward a similar ban, and the Air Force has restricted its use. But what about the safety of the aircraft now in service? There are 400,000 miles of Kapton wire stuffed inside navy F-14s and F-18s, air force F-16s and B-IB bombers, army helicopters, and marine corps jump-jets. It is also the most popular wiring in commercial jetliners, and it can be found in intercontinental ballistic missites and nuclear power plants.

As early as 1982 the Navy's own safety experts claimed that Kapton fires were endangering its aircraft, but pilots were not warned. When the Naval Air Command moved to ban Kapton beginning in 1984, the pilots were informed but the public was kept in the dark. In 1987, when the Kapton...