| John,
I wouldn't buy a first generation car design out of Detroit, since they
tend to be REAL buggy, never mind fly a new, all electronic, airplane
thats got to be a few orders of magnitude more complex. If I had been
you, I'de have got off as soon as I realized that I was about to start
on a "Shakedown" cruise.
|
| I ran across this a few months ago. This seems like a good place
to put it.
!
--+--
G. Schrader o___<0>___o CSS::SCHRADER
* * *
VNS TECHNOLOGY WATCH: [Mike Taylor, VNS Correspondent]
===================== [Nashua, NH, USA ]
A320 Computer Toilets
The main concern about the A320 has been that so many functions
are 'computer-controlled,' and that this could lead to unforeseen
problems. The use of the word 'computer' can be misleading, in
fact, because many of the devices referred to as computers are
little more than digitally controlled switches--like the window
heat computer, whose software has now been spike-vaccinated.
The whole subject comes firmly down to earth in the Air France
A320's, where the high-tech vacuum toilet system chosen by that
airline (but not by BA) has suffered shutdown because of glitches
caused by electrical transients. Aircraft have been grounded by
this problem from time to time. You can get an aircraft airborne
safely without working toilets, but it is unwise to try to get any
passengers airborne under those conditions.
Air France chose the vacuum toilet system for its single-point
drainage and the flexibility to move a toilet quickly for a
short-notice cabin reconfiguration. However, its A320's have been
subject to four different types of toilet system malvunction:
toilet overflow, toilet shutdown, system shutodwn, and straight
forward toilet drain blockage. The latter may be a matter of
wastepipe diameter, though not everyone agrees on that. It has
worked on other aircraft.
Airbus, in its support department's technical review of Air
France's A320 toilets problem, devotes a page to the subject, with
a chart designating specific problems followed by progress towards
rectification. The toilet overflow was caused by a rinse-valve
which was sticking open. The temporary remedy is a valve
modification, but a redesigned valve is on the way. The individual
toilet shutdown and the whole-system shutdown have been caused by
electrical transients which affected the digital flush control
units (FCU--the minicomputer activated by the button which the
user pushes to flush the toilet) and the vacuum system controller
(VSC--another microprocessor). The printed circuit boards for the
FCU and VSC were under study for modification, and new software
should have been supplied for them both by now. As for the drain
blockage, Airbus and the system vendors were examining the suction
unit in thorough system tests, and hoped to have a result by the
end of August.
{Flight International 9/3/88}
{Contributed to RISKS-FORUM Digest 7.49 by Robert Dorsett)
|