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Wednesday, January 13, 1999

The OPPOSING VIEWS

37 Year Wiring Expert (ex Boeing)

Tuesday Jan 12 3:33 PM EST     Wiring installation faulty on Swissair Flight 111     STEPHEN THORNE     HALIFAX (CP) - Sensitive wiring aboard MD-11 jets like the one that crashed     off Nova Scotia on Sept. 2 has been subjected to an unusual amount of     handling and some was improperly installed, The Canadian Press has learned.     A circuit panel where investigators discovered cracked, chafed and cut wire     insulation aboard Swissair Flight 111 and over a dozen other MD-11s was     ordered modified by regulators in 1993, according to documents.     The regulatory directive would have required extensive handling of wires     where the damage was found.     And some electrical wiring was improperly installed last year as part of a     new inflight entertainment system in Swissairs MD-11s, say experts who     studied photographs of the affected areas aboard several other aircraft.     "Things like that are not allowed at Boeing and I'm sure not at    McDonnell-Douglas either," said Patrick Price, a retired Boeing technician.    "They wouldn't dare."    Canadian investigators have found evidence of cracks, chafing and    electrical arcing on wires aboard the plane in which 229 people died.    On Monday, the U.S. National Transportation Safety Board, acting on advice    from its Canadian counterpart, urged immediate inspections of MD-11    aircraft for damaged wiring insulation.    The U.S. Federal Aviation Administration said action is "on the fast track"    after preliminary checks by crash investigators found insulation damage    around two cockpit breaker panels and above the forward cabin doors aboard    more than a dozen MD-11s they inspected last month.    "The inspection should include examinations for loose wire connections,    inconsistent wire routings, broken bonding wires, small wire bend radii,    and chafed and cracked wire insulation," wrote Jim Hall, U.S. board    chairman.    The response by the FAA, aviations top regulator, will probably come in the    form of a safety order to airlines known as an airworthiness directive,    Alison Duquette, an agency spokeswoman in Washington, D.C., said Tuesday.    "We'll respond formally to the board within 90 days, probably sooner. That's    the protocol."    The general-purpose wiring aboard MD-11s is insulated by controversial    Kapton, or aromatic polyimide tape, while the entertainment systems were    powered by wire wrapped in softer Tefzel.    "The cardinal rule was broken," said Price, who helped design Boeings    arc-tracking laboratory outside Seattle. "You don't mix types of wires."    The U.S. military and the planes manufacturer, McDonnell-Douglas, have    found Kapton can wear away softer insulations like sandpaper over the    course of thousands of hours of high-vibration flying.    Price also viewed a videotape of blue wire bundles in an MD-11s overhead    panel and noted some was doubled over and held in place by white plastic    ties - "glaring errors," he called them.    He noted Kapton can be extremely sensitive to handling, especially as it    ages. The U.S. military has effectively banned the material for that    reason.    "Kapton insulation is brittle and can shatter like glass if stressed like    bending over 180 degrees and under vibration from the airplane," Price said    from Tacoma, Wash.    "The cardinal rule at Boeing is that you cannot bend a wire over 90    degrees, period."    Price said it's also evident installers - the job was subcontracted by    Interactive Flight Technologies of Phoenix - used pliers to bend the wires,    another faux pas. He said it doesnt matter whether it was Kapton or Tefzel.    "You don't dare do that with insulation material - you might damage it,"    said Price. "Any time you use pliers to make a bend on wire, that's a no-no.    I saw a couple of examples of that in routing."    Air Safety Week, a trade journal, published photographs this week of what    it quoted unidentified experts as calling improper installation of inflight    entertainment wiring aboard an MD-11.    "Moreover, the practices in these photos seem to conflict with wiring    guidelines contained in the Air Transport Associations Specification 117,"    wrote editor David Evans.    The specification says wiring should be "mechanically and electrically    sound and neat in appearance (and) adequately supported throughout its    length.    "Wires and wire groups should be protected against chafing or abrasion in    those locations where contact with sharp surfaces or other wires would    damage the insulation."    An electrical engineer who requested anonymity said he has viewed    photographs of MD-11 electrical systems and hes convinced installation and    handling of wires found by crash investigators are at the root of Flight    111s demise.    "There are wiring devices and mechanical techniques that have been used to    install this wire that directly contradict well-established, well-developed    practices," said the engineer.    "These practices lead to breaks in the insulation which then have the    possibility of allowing an electrical event to occur."    There is also evidence the areas in question were subjected to work other    than installation of the high-tech entertainment system.    An FAA airworthiness directive dated April 1, 1993, ordered the flight    compartment overhead circuit panel modified "to prevent display units from    going blank, which could lead to momentary loss of flight-critical display    information."    © The Canadian Press, 1999