Originally Posted by Diversification
After following this discussion for some years, I am still wondering about some things.
Why has BEA not released the current software versions used on the computers, e.g. ADIRU:s, Prim:s and Sec:s? These data may perhaps be more important than e.g. engine numbers.
Let me cite the following from ao2008070-final.pdf, §3.5.3 Software versions:
"The ADIRU software was changed from time to time as updates and improvements were incorporated. At the time of manufacture, units 4167 and 4122 had software version -0312 installed. Updated versions were usually promulgated as optional service bulletins140, and operators could decide whether the advantages of installing an updated version of the software were sufficient to justify the logistics of upgrading each aircraft (three ADIRUs per aircraft). The operator of QPA elected not to load software versions -0313 and -0314 in any of their ADIRUs. Software version -0315 was loaded on unit 4167 on 20 July 2005 and was the version installed at the time of the 12 September 2006 occurrence. Software version -0316 was released in August 2008; it was the version installed on unit 4167 at the time of the 7 October 2008 occurrence and it was also installed on unit 4122 at the time of the 27 December 2008 occurrence. As far as could be determined, most of the LTN-101 ADIRUs had software versions -0315 and/or -0316 installed."
Thus apparently at least one case is known where an update in the software apparently de-masked a hidden old software bug in an ADIRU unit.
Since the HABSHEIM flare in the forest (AF, 1988) Nobody (BEA, Lawyers, Judges, Experts, Pilots, aso) understood nor wanted to understand how much these points are important, how real-time flying softwares work very different of traditional systems. Only one BIT 0/1 is generally false and the whole system fails... Nice exemple the ARIANE V (V501 Jun 4. 1996) where the false carry costed 8 billion FF.
Originally Posted by Diversification
We are faced with a small number of UAS cases which may have increased in frequency with time. That could perhaps point not only to increasing icing but also to new software revisions making the UAS events more probable. Secondly the difference in probe type behavior might also be connected to ADIRU software and its sensitivity to e.g. noise and flutter on the signal from the probes - not necessarily only to sensitivity of probes to icing conditions
Flutter ?
Originally Posted by Diversification
A final remark is about redundancy and diversification. Redundancy is normally a repetition using the same equipment and systems which seldom helps to avoid problems which are due to a common cause. Diversification means that different methods and equipment are used as parts in several separate and parallel channels of a system. This reduces the risk of common mode failures
We will do ! Thank you. Vocabulary is important.
Originally Posted by Diversification
I am not a pilot and these comments are only a few thoughts from one who has spent a long life writing real-time software and also directing/overseeing national research on nuclear power safety,
Best regards to all. Keep this interesting thread going
Thank you for your science pages crosscheck ! This thread is interesting due to the many differences of all of us.
