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Old 6th Sep 2012, 01:24
  #293 (permalink)  
andianjul
 
Join Date: Feb 2011
Location: Australia
Age: 58
Posts: 15
Pitot Failure Detection

The voting logic as described makes sense, unless as postulated two pitots block simultaneously and the remaining good pitot is out-voted by the logic. However, this approach is decidedly simplistic and I propose that it’s possible that the explanation of the voting system lacks a thorough knowledge of the low-level workings of the system. I do not possess such knowledge, however, if I were to design an air-speed sensing system one of the features (the design of which has been possible and therefore available to aviation designers/engineers virtually since the invention of the transistor) that I would incorporate is ‘signature’analysis. Basically, the electrical ‘signature’ of a valid signal from any pitot that is being impacted by air molecules will appear decidedly different to the ‘signature’ from a blocked pitot. Essentially, the signal from the blocked pitot will lack the ‘noise’ of the unblocked pitot. Sure, the block pitot can yield data, albeit invalid, and may function more as an altimeter than a speed sensor; but the absence of the minutia of the electrical information from the transducer that is being bombarded by air molecules is something for which the designers can easily test and its absence should inform the system to preclude the data from the ‘known’ blocked pitot. Then the notion of simultaneously blocked pitots being used to out-vote a functioning pitot is rendered moot.
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