Archives For A380

QF32 Redux

29/03/2011 — Leave a comment

QF32 - No. 1 engine failure to shutdown

The ABC’s treatment of the QF 32 incident treads familiar and slightly disappointing ground

While I thought that the ABC 4 Corners programs treatment of the QF 32 incident was a creditable effort I have to say that I was unimpressed by the producers homing in on a (presumed) Rolls Royce production error as the casus belli.

The report focused almost entirely upon the engine rotor burst and its proximal cause but failed to discuss (for example) the situational overload introduced by the ECAM fault reporting, or for that matter why a single rotor burst should have caused so much cascading damage and so nearly led to the loss of the aircraft.

Overall two out of four stars :)

If however your interested in a discussion of the deeper issues arising from this incident then see:

  1. Lessons from QF32. A discussion of some immediate lessons that could be learned from the QF 32 accident;
  2. The ATSB QF32 preliminary report. A commentary on the preliminary report and its strengths and weaknesses;
  3. Rotor bursts and single points of failure. A review and discussion of the underlying certification basis for commercial aircraft and protection from rotor burst events;
  4. Rotor bursts and single points of failure (Part II), Discusses differences between the damage sustained by QF 32 and that premised by a contemporary report issued by the AIA on rotor bursts;
  5. A hard rain is gonna fall. An analysis of 2006 American Airlines rotor burst incident that indicated problems with the FAA’s assumed rotor burst debris patterns; and
  6. Lies, damn lies and statistics. A statistical analysis, looking at the AIA 2010 report on rotor bursts and it’s underestimation of their risk.

A report by the AIA on engine rotor bursts and their expected severity raises questions about the levels of damage sustained by QF 32.

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It appears that the underlying certification basis for aircraft safety in the event of a intermediate power turbine rotor bursts is not supported by the rotor failure seen on QF 32.

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The ATSB release the preliminary report on the QF 32 A380 uncontained engine failure. While the report sheds light on a number of key issues in the investigation and certainly provides a ‘smoking gun’ for the engine failure I was left a little underwhelmed by the entire report.

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The recent Qantas A380 catastrophic engine failure illustrates the problems of dealing with common cause failures in system design.

Updated: 15 Nov 2012

Generally the reason we have more than one of anything on a passenger aircraft is because we know that components can fail and N+1 redundancy is the cornerstone strategy to achieve the required levels of system reliability and safety.

But while overall aircraft safety is predicated on notionally independent components, the reality is that the catastrophic failure of one component can also affect adjacent components and systems leading to what are termed common cause failures. Continue Reading…

How do ya do and shake hands, shake hands, shake hands. How do ya do and shake hands and state your name and business… Tweedle Dum & Dee (Through the Looking Glass)

Lewis Carrol

Yes Alice, Some folk still believe in N Versioning

You would have thought after the Leveson and Knights experiments that the  theory that independently written software would only contain independent faults was dead and buried.

Another beautiful theory shot down by hard cold fact.  Unfortunately like conspiracy theories the theory of n-versioning keeps on keeping on (1).      

Now this would be of only passing interests if it weren’t for the fact that engineers actually continue to build systems that relay on what is effectively pseudo-scientific gibberish (2).

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