TWICE AS FAR

 

SWISSAIR 111

CRASH INVESTIGATION

 

 

 

- EXTRACT FROM FILE NOTES -

 

 

FOR

- 2000 DEC 13 -

 

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00-12-13  0700    Morning routine.

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            TSB packed all their equipment into the moving truck today, except for Johnís office, and the truck pulled out at noon.

            I photocopied the last of my notes up to this morning and put them in the binder for the file.  The photocopier is now gone, so anything more will be done at the last all at once.          

            Larry FOGG decided to run a yellow polypropylene rope in the frame in place of the IFEN wires, so gave him a hand with the MD-11 tour to show the routing on the aircraft that was photographed.  This doesnít necessarily mean that this was the routing on HB-IWF, but it would be close.  Then had a chance to ask him some questions about the materials present.  He feels that the green canvas-like and rubber-like material above each of the doors in not very flammable.  This has yet to be checked, but if so, then it reduces the fire load on the slide panels above the door.  Then, I asked if the wire runs were anywhere near being accurate.  He pointed out a clamp on the right side at the waterfalls that is where it is supposed to be, but there is no way of knowing if the wires pulled through the clamp at the time of the crash.  However, they are likely within a foot of being accurate.  We discussed the amount of burning on the wires on the right-hand side, and it seems that this run of wires has undergone considerable heat, burning off the outer coating, leaving the Kapton material surrounding the copper wire.  This material does not burn, so it is deceiving to see it with the covering. 

            The wire run on the left-hand side appears to largely be unburnt, apparently protected by the fibreglass fourth duct to the fifth zone.  I had considered that this duct would be consumed and add to the fire load, but it would appear that it did not as the wires are intact.  Another point to consider is the fact that the ducts are wrapped in fibreglass insulation, and then covered with the Metallized Tedlar or Mylar material, a single wrap.  So, there is only one layer of Metallized Mylar to burn, plus any tape that is added.  At two places, there is another wrap of insulation covered both sides with Tedlar or Mylar, usually Metallized Mylar.  So this fact actually reduces the fire load.  Of course, the hull insulation is actually four layers of Metallized Mylar, with two layers of fibreglass insulation.  However, how much of this failed to burn and floated away not to be found.

            So the bottom line here is that the amount of fuel above the ceiling that actually burnt is unknown, and is highly variable.  The 1R forward door drum shows heat damage and melting to one area, yet the plastic on the wires is untouched in other areas.  At the same time, according to FOGG, the frayed wire ends going up and down from the drum are show heat damage and embrittlement.

            This afternoon, the security-engineering people were in to reset the alarm in my two rooms.

 

 

 

 

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