NTSB announcement regarding flight 800

Date:         16 Dec 96 03:15:38 
From:         "P. Wezeman" <pwezeman@blue.weeg.uiowa.edu>
Organization: The University of Iowa
Followups:    1 2 3
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   On Saturday, December 14, print and broadcast news media reported that
the National Transportation Safety Board had made several recommendations
to avoid a repetition of the type of mishap that destroyed TWA flight
last July. They recommended that:
   1. Inside fuselage fuel tanks on airliners be thermally isolated from
sources of heat inside the plane.
   2. Such fuel tanks have added to them while on the ground such amounts
of cold fuel as needed to ensure that the temperatures inside the tank
not get so high as to form an explosive fuel vapor-air mixture.
   3. Over the longer term airliners be equipped with systems to keep the
ullage spaces in such tanks filled with nitrogen gas instead of air. I had
the impression that they were talking about a retrofit to present aircraft.
   They also announced that they consider it possible that the explosion
was triggered by a static electricity discharge.
   I do not have any informants inside the NTSB, but it seems to me that
their recommendations are consistent with long standing policy that it
should always take at least two separate and independent failures to cause
the loss of an airliner. In this case, fuel tank explosions were thought to
be prevented by the fact that there was no source of ignition in the tanks
and that jet fuel was too non volatile to form an explosive mixture at any
temperature that would be encountered in normal operation.
   Presuming that flight 800 was destroyed by one of the several ignition
sources that has been proposed, unless we can find and identify the exact
cause it will be very hard to guarantee that it couldn't happen again. If
the cause is some small component it may be that it will never be found, or
that it could take years.
   However, it is still possible to have redundant protection from fuel tank
explosions by ensuring that in normal operation there is no oxygen in the
tanks, and, of course, also taking steps to keep the fuel from becoming
overheated. As far as I could tell from the news stories, the nitrogen
system was only considered to be necessary for the fuselage tanks, but
it was recommended for all airliners with such tanks and not just for 747s.
One presumes that the search for the specific cause of the destruction of
flight 800 would continue regardless.

                        Peter Wezeman, anti-social Darwinist

                             "Carpe Cyprinidae"