PJ2

Vapilot2004:
Yes, I think so. In fact I posted a long summary of an Airbus OEB on this thread a while back and either can't find it for looking or it's been deleted. The OEB, issued June 2007 and remains in effect until "Corrective Action" takes place as follows; - The OEB is cancelled "upon the installation of [an] F/CTL PRIM (FCPC) and a SEC (FPSC) software standard as follows", and the OEB goes on to state the references which apply.

The OEB discusses certain PRIM1 or servo controller failure modes, (which may or may not be associated with a Green hydraulic system pressure loss), a "dual independant failure" can occur which results in the loss of control of the associated elevator. The OEB states that this fault would normally be seen on the ground during the control check but there is provision for crew response if the messages occur In-flight. The associated in-flight ECAM messages referenced by the OEB are:

F/CTL PRIM1 FAULT
F/CTL PRIM1 PITCH FAULT
F/CTL ELEV SERVO FAULT
HYD G SYS LO PR

The OEB requires that if any of these messages occur, normal ECAM and STATUS procedures are to be applied by the crew.

In normal operation, each elevator is actuated by the Green servo control in active mode and controlled by the FCPC PRIM1 (Flight Control Primary Computer 1) while the other servo control is in "damping mode".

The OEB explains that if a failure occurs with PRIM1, the associated green elevator servo control or the associated hydraulic system, control is transferred to PRIM2 and the associated servo control becomes the "active" servo while the other servo reverts to damping mode.

The "dual independant failure" as a failure of the second servo control to change from the damping mode to the active mode and the failure of PRIM1 to detect this. The result is a loss of control of the associated elevator.

In referencing the QF flight, apparently there were ECAM messages just before the incident. We don't know what those messages were, nor do we know if the above description applies to this incident. The OEB has been effective for more than a year and will likely have long since been enacted. This description of the OEB is only provided for information and interest.

airtags

good bgd - thnx PJ2

be interested to know what those ECAM msgs were >

reading some posts and some poorly written pieces by journos that should (and one certainly does) know better, it seems that the line between reason and blame has wrongly become a floating absolute. - and to be fair, Q's media unit has been outstandingly below average (yet again) in being proactive and standing up for the crew.

Miles CNN pls note: - mate save the story for the final investigator's report when one can deal with fact rather than tabloid hypothesis. Besides, running it now will only be a 1 minute filler for the Obama McCain title fight mini series and probably will be dropped before the 10pm bulletin.

AT

sevenstrokeroll

Miles CNN

saw the piece...felt it correctly explained that while very unlikely, the scenario with the laptop/cellphone etc. is worth investigating in a scientific manner.

keep it up.

Brian Abraham

Interesting that over on D & G Reporting Points it is said that the aircraft was over stressed in the negative and the question raised is how this could happen with the so called FBW envelope protections provided. Reverting to direct law is one suggestion, so the question from this bystander is how could it revert to direct law?

sevenstrokeroll

IF the plane was overstressed, then DOUBLE congratulations to the crew for landing at the first available,suitable field.

YRP

Say again? VLF is less that 30 kHz. Computer chips are well into the MHz range.

Plus shielding against low frequency interference is simple. It's higher frequencies that can be challenging.

For the CNN chap, no real chance of this being laptop/cell phone interference. The danger from digital devices used by passengers is interference with analog navigation signals (eg 25-33 MHz processor generating harmonics in the 100 to 133 MHz realm where the VOR/ILS signals live). It is much less likely to interfere with a digital computer - they have to tolerate much self-generated noise as it is.

sevenstrokeroll

so how do you explain the wireless mouse which caused a different QANTAS plane to go off course...published reports.

hmmme?

Barkly1992

I don't think the digital mouse story was ever verified.

My understanding is that it is often the case that crew see a deviation, can't find an immediate explanation - ask a flight attendant to check whether there are any computers/handheld devises being uses. Answer is yes - conclusion drawn.

then incident cannot be replicated.

Might as well ask whether any blondes in the cabin - answer is yes 10 - ergo - 10 blondes will cause navigation deviation.

NSEU

With great difficulty...

Airbus Flight Control Laws

Comoman

A COMPUTER fault caused the autopilot system to be overridden, sending a Qantas plane into a mid-air plunge over Western Australia last week, authorities said tonight.

The air data computer - or inertial reference system - for the Airbus A330-300 sent erroneous information to the flight control computer causing the autopilot to disconnect, the Australian Transport Safety Bureau (ATSB) said.

More than 70 people on Qantas flight QF72 from Singapore to Perth were injured on Tuesday last week when the Airbus, carrying 303 passengers and 10 crew, suddenly dropped altitude.

People were hurled around the cabin and the pilot was forced to make an emergency landing in Western Australia's north

Source: Computer fault caused Qantas plunge | NEWS.com.au

Just a Grunt

philtee

Released today, on line here -
MEDIA RELEASE : 14 October 2008 - Qantas Airbus A330 accident Media Conference

ZEEBEE

In my opinion the press release raises more questions than it answers.

Surely the A330 and other FBW aircraft don't rely solely on one Inertial reference unit. What happened to the triple redundancy/majority vote systems that the normal law requires before switching out to one of the more direct operating laws ?

If it doesn't use the triple redundancy, then this sort of behaviour could ostensibly happen on short final before the 50ft rad Alt switchover.

That to me is VERY scary.

ampclamp

one auto pilot engaged at altitude, all that triple redundancy is for approach and auto land.one a/p one adiru feeding it.

but....

yes its concerning even so given command/monitor systems involved and would have thought cross checking between adirus may have voted out the dud info.
I'm as surprised as anyone such an excursion can happen to the extent it did.

over to you mr airbus........

ampclamp

hi 7,
if a 'bus or any fbw aircraft could be sent off heading/course by a normal wireless mouse I reckon there'd be regular carnage all round the world by now.

ampclamp

Your question re hi power vlf RMI.
Is this related to the old omega/vlf stations that are or were located in that area of WA?
Dont know if they are still in use but I'm reasonably sure the massive wavelength of a 10 to 30 khz radio signal would do absolutely jack to aircraft systems .

Fizix

About 2 minutes after the initial fault, ADIRU 1 generated very high, random and incorrect values for the aircrafts angle of attack.

Teal

Australia's Omega Navigation System in Eastern Victoria now operates as a VLF communications facility for navy subs. There used to also be a VLF facility on the north-west cape area past Exmouth(!) in Western Australia operated by the USN if memory serves. I believe it is closed now*...

* I see from Google Map's Street View that the VLF antenna system still stands!

ampclamp

thanks teal, I thought they'd been decomm'ed over there.The line of enquiry by nev nobody led me to thinking this is what he may have been getting at.

Is that the antenna (in VIC) the nutters have done the BASE jumps off?

Capn Bloggs

The latest ATSB statement puts paid to the conspiracy theories about Qantas pilots flying around with newspapers all over their windscreens unable or unwilling to disengage the AP.

I don't fly Airbus, but I find it almost unbelievable that a modern jet could do what QF 72 did (the same goes for the MAS 777 a couple of years ago).