Re: [sc] aircraft maintenance practices



Re: [sc] aircraft maintenance practices

From: Brian Reynolds <bareynolds3_at_xxxxxx>
Date: Thu, 26 Aug 2010 09:01:29 -0700
Message-ID: <AANLkTimbhn6EWEKxBj_qOh0VcGZeuTpVXuMFYyQevdnY@xxxxxx>
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This is totally bogus.

(1)  There may have been a trojan in a *ground *maintenance computer
(2)  The maintenance issue was related to a temp sensor in a hot air duct
(redundant sensors, aircraft was dispatched with on inoperative) and has no
direct or indirect effect on either flaps or slats.
(3)  The maintenance system failed to flag the fact that three problems wit=
h
this temperature sensor had been reported (i.e. it's not the sensor it's th=
e
wiring) (note that the maintenance system includes the procedures which
allows up to 24 hours to update maintenance records.)
(4)  The flight crew failed to set flaps and slats prior to takeoff
(5)  The flight crew failed to execute their checklist properly (also misse=
d
turning on landing light prior to start of takeoff)
(6)  The takeoff warning system failed to alert the crew of improper
configuration for reasons unknown (this is a discrete logic box - no
processing capability at all. Simple, transistors, resistors, you know
1960's stuff)

Also see Northwest Flight 255 - same type of accident

Also see:
http://airplanes.suite101.com/article.cfm/fatal_crash_of_spanair_flight_502=
2
<http://airplanes.suite101.com/article.cfm/fatal_crash_of_spanair_flight_50=
22>and
of course:
http://en.wikipedia.org/wiki/Spanair_Flight_5022
<http://en.wikipedia.org/wiki/Spanair_Flight_5022>
http://en.wikipedia.org/wiki/Northwest_255

<http://en.wikipedia.org/wiki/Northwest_255>The NTSB report for Flight 255
is at http://www.airdisaster.com/reports/ntsb/AAR88-05.pdf

The MD-8x is a very mechanical aircraft, with all controls being directly
connected to the flight crew controls by means of cables. The aircraft can
fly (not recommended of course) without electrical power).  The slats
(leading edge life devices) and flaps (trailing edge lift devices) are
manually set prior to takeoff based on runway length, air temperature, and
initial climb out characteristics. With these devices not extended, for a
given airspeed the wing will not develop sufficient lift. Once out of groun=
d
effect (an area of compression between the wing and the ground) with
insufficient lift the aircraft will be very difficult to control.  This is
basic airmanship. If you watch the video of the takeoff, this is exactly
what happened. The aircraft accelerated, at the proper airspeed it rotated
and started to climb, got off the ground, rolled and impacted the ground.

If you want to have a discussion as to why, given that there was an
identical crash in 1987 (NW Flt 255) which also involved failure of the
Central Aural Warning System (CAWS - see paragraph 2.5 of NTSB AAR88-05) to
annunciate a misconfiguration when takeoff power was applied, that might
be appropriate. (i.e. what failed in the safety process to allow a systemic
latent fault to exist)  Note that the fix is to have a preflight check of
the CAWS to check its ability to function properly. If we go back and look
at the NTSB recommendations (the NTSB can only recommend action, regulation
is the responsibility of the FAA)

*The sound spectrum analysis testing conducted in the Safety Board=92s audi=
o
laboratory*
*permitted the Board to identify the takeoff warning=92s failure mode. Of
primary importance to this*
*analysis was the fact that the two SSRS alarms are connected to different
power supplies in the*
*CAWS unit: SSRS-2, the first officer=92s alarm, was connected to CAWS powe=
r
supply-3; and SSRS-1, the*
*captain=92s alarm, was connected to CAWS power supply-2. The takeoff warni=
ng
system also was*
*connected to power supply-2.*
*
*
*When both SSRSs operate, an echo effect will be heard. The sound spectrum
analysis of*
*the actual warning generated by the accident airplane=92s CAWS unit showed
that there was no echo*
*effects, that only one SSRS had provided the alarm, and that, based on the
frequency components of*
*the word, SSRS-2 provided the alarm recorded by the CVR. This conclusion
was further corroborated*
*by the facts that no significant damage was noted on the filaments of
either of the captain=92s bulbs;*
*however, stretching, typical of an impact while the bulb filament is hot,
was found on both bulbs of*
*the first officer=92s warning light.*

and later:

*The Safety Board supports the change to the MD-80 checklist contained in
the Douglas*
*telex as well as the efforts of the FAA to include flightcrew procedures i=
n
airplane checklists that will*
*allow crewmembers to validate the operational capability of takeoff warnin=
g
systems. Until such*
*time as warning systems can, through the operation of internal self-testin=
g
equipment, furnish*
*notice to a flightcrew that they are inoperative, these checklist
procedures will enhance the*
*flightcrew=92s ability to detect and deal with a failed takeoff warning
system.*

Perhaps "lack of an adequate industry safety culture and regulatory
oversight by regulatory authorities " might be sited as a cause for Spanair
5022?

But malware? A computer virus in a ground maintenance system? (or as one
group is going on about "Windows blue screen of death becomes real?"

No way.

On Thu, Aug 26, 2010 at 7:14 AM, Loebl, Andy <loeblas@xxxxxx> wrote:

>
> Computer viruses may have contributed to Spanish 2008 plane crash
> Aug 20, 2010, 10:13 GMT
>
>
> Madrid - Computer viruses may have contributed to the Spanair passenger
> plane crash which killed 154 people in Madrid two years ago, the daily El
> Pais reported Friday.
>
> The Spanair central computer which registered technical problems in
> airplanes was not functioning properly because it had been contaminated b=
y
> harmful computer programmes, according to an internal airline report quot=
ed
> by the daily.
>
> The MD-82 plane had three technical problems, a situation which should ha=
ve
> prevented it from taking off.
>
> The plane en route to the Canary Islands veered off the runway and burst
> into flames immediately after take-off on August 20, 2008. Eighteen of th=
e
> people on board survived the accident.
>
> Experts are still investigating the causes of the crash, which has been
> attributed mainly to the fact that the plane's wing flaps and slats were =
not
> deployed to help it take off.
>
> A mechanic and an airport maintenance chief have been indicted as suspect=
s
> in the case. The final report by the investigating commission is due in
> December.
>
>

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Received on Thu 26 Aug 2010 - 17:01:36 BST