ANNEX W

Three Decades of

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Aircraft

Wire

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       Ed Block
       He wrote a letter to AlgoPlus Consulting Ltd. in Halifax, of which
       the contents I quote in full here: "I’m sorry I couldn’t get back to
       you sooner, but things are definitely moving fast. I wanted to first
       congratulate you on being able to appreciate the need for statistical
       analysis in making any meaningful decision (although obviously limited
       by the quality of that data). The problem then is how to fine-tune the data.
       In 1982 I conducted a survey of the major aircraft manufacturers who
       were members of the SAE’s High Temperature Insulated Wire Committee
       (see enclosure #1). This poll provides keen insights into the evolution
       of the design criteria used in the selection of various wiring insulation
       types for the initial construction of these aircraft. I have since acquired
       additional documentation (see enclosure #2) that amplifies the specific
       changes that were made, and obviously only when an insulation material
       was shown to fail. The move from Polyvinyl Chloride (PVC) used since
       jet-powered aircraft, came about due to the insulation material failing the
       FAA’s only prehistoric flammability test (60 degree and no smoke test). It
       was followed with the introduction of Poly-X wire in 1969 (early DC-10s and
       747s). Its demise came in 1975 when the premature aging problem was discovered
       /admitted. This inherent quality of the insulation material resulted in radial
       -cracking of the insulation, down to the conductor. Next came Stilan, this
       insulation material had a stress-crazing problem (internal shattering), in
       addition to its susceptibility to de-icing fluid and hydraulic fluid, causing
       it to be replaced in 1978. Then came XL-EFTE (MII-W-22759/34,55 or irradiated
       tefzel) and even though it has a 97% smoke optical density rating (see enclosure
       #3) it is still being used today by Boeing in its 747, 767, and 777 lines. This
       is particularly alarming when you consider Grumman Corp. had banned it in 1982
       from manned-aerospace flights, due to the insulation’s toxicity, and NASA’s
       subsequent ban in 1983, when they (NASA) determined this material could explode
       in an oxygen-enriched area (e.g. cargo-bay). The subsequent decisions on the ‘by
       default’ use of Kapton go back to 1972, when arc-tracking was first re-created
       by Lockheed Corp. in a laboratory. In 1977, TWA had asked Boeing not to put this
       insulation in anymore of their aircraft, and by 1984, the FAA’s own internal
       documentation showed the problems being experienced with this material. In 1987,
       the military finally banned Kapton from further use, and in 1988 the FAA
       conducted their own experiments on arc-tracking after receiving a letter from
       the Energy and Commerce Committee, based on my (Block’s) prior briefing to them.
       The majority of aircraft built today should hopefully now have TKT, a composite
       construction, that should limit problems in the future, however political issues
       have remained in the equation to this day.
       In 1992, I briefed the GAO’s Transportation Dept. on this problem (see enclosure #4).
       They sent letters to the NTSB/FAA asking them if there was indeed a problem with
       the various wire insulations used in commercial aircraft. Their respective replies
       clearly indicated that the problem with wire insulation was that no one was in a
       position to even know if there was one. They relied totally on the manufacturers
       for this expertise. In 1994 I briefed the FAA in Seattle and Atlantic City, NJ,
       on the problems associated with the various types of degrading wire, that the
       Military had experienced. Their answer was indicative of the aforementioned real
       problem (see enclosure #5), that no one had a clue to the seriousness of the matter.
       In 1995, I had the NTSB/FAA form a Joint Task Force to address this matter more
       fully. The results of them once again asking only the manufacturers for an assessment
       of any problems with aircraft wiring was predictable, there was no problem. The
       NTSB replied in February, 1996, the FAA (after ValuJet 592 and TWA 800), in November
       of 1996. I then turned to the White House Commission and my efforts in supplying
       them with documents and video-cassettes finally paid off (enclosure #6). They
       acknowledged that non-structural components e.g. wire and cable had been overlooked
       in regard to safety concerns in February 1997.

On April 10, 1997 I briefed Congress, the FAA, the FBI, the DOTIG, GAO, the NavyDept.,
       etc. on the problems with wiring in aircraft. The result: there was no problem showing
       up in the database. I have given this brief history to underscore the need to
       analyze/isolate wire failures by type. Enclosure #7 is therefore the reason I am
       writing to you. The last sentence on page 1 is the root of this matter, that being
       that the FAA still maintains that wire is wire. Even though the FAA contradicts
       themselves on this issue at every turn (see enclosure # 8), they still want to group
       wires into one nondescript bundle, that ultimately gets replaced in the course of the
       aircrafts life. Similarly it is supposed, that as long as they are maintained in the
       interim, they will last the life of an aircraft.
       The information presented herein proves conclusively that wire is not wire. The
       statement cited in the 3rd paragraph of the NTSBs response (see enclosure #9) concurs
       with this. The statement in the subsequent NTSB response (enclosure #10) further proves
       the distinctions made in wire types.
       This brings us to the current need, as evidenced by the FAAs Non-Structural Systems
       Plan announced October 1, 1998. In the Plans Findings (see enclosure #11) they clearly
       state there is currently no systematic process to identify and address potential
       catastrophic failures caused by electrical faults of wiring systems, aside from accident
       investigation associated activities. This declaration is more telling than it may appear,
       beyond the fact that the Plan makes no distinctions regarding the various wire types nor
       their related failure modes. (Enclosure #12) is a clear case in point, in that this
       letter from the NTSB (accident investigation phase that the FAAs Plan is relying on),
       acknowledges that even they cannot correctly distinguish between various wire types
       (Sorry, it is not Kapton, it is XL-EFTE).
       Therefore, since the FAA admits to allowing the manufacturers to choose the wire types
       for their aircraft, and they do not then call for any comprehensive flammability and
       smoke tests (like they do on seat-covers) to prove they are safe, and since the FAA
       says there is currently no systematic process to address potential catastrophic wire
       failures in advance, (clearly the NTSB is obviously not up to the task either, other
       than relying on those same manufacturers the FAA originally relied on, via the party
       system), and in that the FAA is not alerting the pilots of Kapton wired aircraft to not
       reset circuit-breakers since wire is wire, something needs to be done.
       I would like to see the development of a model by model SDR base, that is linked
       specifically by wire type used. I do not know what this would take, but I would like
       your opinion/input. This would provide a more fine-tuned look at the problems related
       to the wiring we are facing, and dispel the notion that wire is replaced, maintained,
       or that wire is wire. Also, when the wire manufacturer announced Poly-X wire they said
       perhaps it could last 60,000 hours. TWA 800, wired with Poly-X had 93,303. That is the
       next hurdle, establishing a realistic life-expectancy for wire.
       Please let me know of any questions or comments.
        Sincerely,
               Edward Block

    

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