The EXPERT VIEW or the OFFICIAL VIEW of KAPTON?
Kapton and airplane crashes seem to have become inextricably linked since Swissair Flight 111 crashed off Peggys Cove. The controversial wiring insulation has been tied by some experts to everything from the Swissair crash to hundreds of other smoke- and fire-related airline incidents over the past 20 years. But while some compare the potential hazards of the insulation to dynamite, others say statistics don't back up such claims.
Price calls the Kapton coating "the most explosive insulation of any of the wires that I know of. It's just like a dynamite fuse. When it goes, it will continue as long as one wire has got electrical energy in the wire bundle".
He describes a phenomenon known as arc-tracking, which happens when the insulation breaks down and a surge of electricity escapes and sparks along the rest of the wiring. The fire, Mr. Price says, spreads rapidly, consuming everything in its path. He calls several U.S. Federal Aviation Administration initiatives since the Swissair crash a smoke-screen for the real danger aboard commercial aircraft. The FAA recently recommended airlines replace two types of aircraft insulation blankets used on most of the world's airliners, saying the materials - metalized Mylar and Tedlar - can spark fires.
The blankets are located between the structure and the interior lining of airplanes, insulating the cabin and cockpit. The recommendation could be followed up by a mandatory directive within six months. Aviation authorities in other countries traditionally follow FAA directives. But Mr. Price says the recent FAA recommendation ignores the root of the problem. "The insulation blankets have to have an igniter", he said. "That igniter is the wiring". He also criticizes an FAA plan to inspect aging aircraft for lint, metal shavings and debris that can gather on wire insulation. " That's smoke and mirrors . . . absolutely PR work", he said. "The FAA has known about the dangers of aircraft wiring for over 20 years", If they are going to clean off the lint, well, this lint has to have an igniter". Neither the FAA nor the airlines want the public to know how dangerous aircraft wiring is because of the cost of replacing it and potential lawsuits, Mr. Price said. The MD-11 was built by McDonnell-Douglas, which has since been bought by Boeing. Price developed the company's arc-tracking laboratory in Seattle, where he conducted tests revealing what he calls the highly explosive nature of Kapton. He and other aviation insiders point to the fact that the U.S. military started phasing Kapton out of its planes in 1986 because of its tendency to degrade when exposed to extreme heat and wet conditions. Mr. Price also developed an arc-resistant wiring known as TKT [layers of Teflon wrapped around Kapton], which he certified for use aboard Boeing 737s and 757s in 1992. Boeing - the world's largest airplane manufacturer, with 10,000 commercial jets currently operating, about 80 to 90 per cent of the world's fleet - now uses TKT as its general purpose wiring insulation in all new planes, company spokesman Russ Young says: "We changed to TKT for a variety of reasons; safety was not one of them", he said, adding that the insulation is cheaper and lighter than Kapton and has better abrasion resistance. "There's been no direction of the National Transportation Safety Board, the FAA ... or anybody else, to stop using Kapton", Mr. Young said, adding that "horror stories about the insulation are unwarranted". "We've operated jet airplanes for 40 years, a lot of those years with Kapton insulated wiring on them, and we don't have a single service bulletin, airworthiness directive or problem that anyone has identified or has needed direction on".
Chafing on all types of insulation is the main "enemy" of airlines, he says, and that " really has to do more with the way the wire is installed as opposed to the way it's insulated. And that's the kind of situation ... we try to design to avoid in the first place. Second, when we find [a problem], we'll take action to correct". "If you go back and look through the history ... to regulatory action or just recommendations by the manufacturers, you're going to find that they're related to that kind of [chafing] problem and not the chemical properties of the insulation".
But Price points to the FAA's own tests as evidence Kapton is dangerous. For example, a 1988 FAA technical lab report on testing of wet-wire arc-tracking notes that the ability of wire to resist the phenomenon "is highly dependent on the composition of the wire insulation". In highly technical language, the report goes on to say the thermal degradation of Kapton when exposed to high temperatures can lead to "severe arcing or flashover".
The 1989 FAA tech center report, for which wires were tested under dry conditions, found Kapton samples "formed a conductive char upon thermal degradation, and severe arc-tracking occurred".
But Boeing's spokesman Young argues that just because arc-tracking can be created in a laboratory doesn't mean it occurs regularly on aircraft. "We can get any wire to arc-track if we torture it enough, but it simply has not been a problem on our airplanes". He says thousands of planes continue to fly with many kilometers of the insulation aboard, and that there would be more problems if it were as volatile as some say. "We feel very passionately about safety" Mr. Young said. "We have looked and looked at looked at the service history of those airplanes, we looked at every wiring problem we have had on every airplane, and none of them come back to the insulation type".