Airbus To Modify A330/A340 Software in Wake of Accidents

The second “interim factual” report to the Qantas A330-300 that dove 1000 feet in minutes has just been released [opens as PDF].

Airbus is modifying the flight control software in A330s and A340s. An interim modification will be made to all Qantas A330s by the end of this month. A standard modification for all A330s and A340s will be certified next year and then retrofitted to all A330s and A340s.

Big news item so far:

In addition to the initial procedures-based safety action takenby the aircraft manufacturer in response to this accident, Airbusis modifying the flight control primary computer (FCPC or PRIM)software used in the A330/A340 fleets to prevent any future similarproblems leading to an uncommanded pitch-down event. An interimmodification to the FCPC software standard is being installed inthe operator’s fleet, and the installation is expected to becompleted by the end of November 2009. A later FCPC softwarestandard to improve the treatment of all ADIRU parameters will becertified in mid to late 2010, and will then be retrofitted to theworld-wide fleet of A330/A340 aircraft.

(Emphasis added.)


The problem

One of the three ADIRU units is at fault, as the ATSB reported in its first report. But the big question of what caused the fault (i.e. erroneous data resulting in the aircraft plunging) still remains unknown.

1:41 PM–Mainstream media reports are now trickling out, and one article is putting possible blame on “cosmic rays”. While the report does mention cosmic and solar radiation have the potential to interfere with systems, the official language is “The investigation team is evaluating the relevance, if any”. So don’t go wrapping yourself up in aluminum/tin foil quite yet.

What the ATSB is focusing on

Since this incident is caused by software gone astray, the ATSB will “examine various aspects of the flight control primary computer (FCPC or PRIM) software development cycle including design, hazard analysis, testing and certification.” The conclusion will be presented in its final report, due out in 2Q 2010.

What the ATSB has done since the first report

The ATSB has disassembled, examined, and tested the faulty ADIRU from the Qantas A330-300 that operated QF72. This did not yield any information related to the accident. Additional testing may be carried out.

The ATSB installed a different ADIRU on the accident aircraft, VH-QPA, and performed a number of checks during a 11 hour test flight (with no revenue passengers) around Australia in May 2009. There were no abnormalities.

Relation to other incidents

  • Jetstar A330-200 incident (February 2008)

At the time of releasing its first report into this accident, the ATSB was focusing on similar ADIRU failures (but which didn’t cause any dives or other “upsets”). One incident involved a Jetstar A330-200, whose ADIRU were made by the same manufacturer of the Qantas A330-300s,  but the ATSB says it now believes the Jetstar incident is unrelated to the Qantas incidents. (There were three incidents on two A330-300s.)

  • Air France A330-200, AF447 (June 2009)

While the ATSB noted the French investigation is ongoing and the reasons for the accident have not yet been determined, the ATSB also pointed out a number of differences between the Air France and Qantas incidents. The ADIRU units and pitot probes on the Air France and Qantas aircraft were each made by different manufacturers. Cockpit messages on Air France and Qantas showed a different sequence and pattern of events.

What next?

The ATSB says it is going to continue focusing on 1) why the ADIRU provided erroneous data, and 2) the role of flight control software.

A final report is due out in the second quarter of 2010.

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