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Old 4th Dec 2018, 11:47
  #78 (permalink)  
infrequentflyer789
 
Join Date: Jan 2008
Location: uk
Posts: 780
Originally Posted by Machinbird View Post
Infrequentflyer, I think we can easily explain the WTF point on the graph you presented.
Siince the aircraft is not yet airborne, that is probably brief jet blast impingement on the nose of the aircraft.
Thanks, hadn't thought of that. Could the asymmetry between sides then be due to the aircraft turning at the time?

Additionally, Mr. Lemme has called attention to the difference in signal between left and right AOA while taxiing. The left AOA was noisy and the right AOA was rather smooth in that segment of the FDR data.
IMO that would be typical of a sneak circuit that is being excited by vibration transmitted by the landing gear into the fuselage.
Yep I've been thinking that way too, Mr Lemme doesn't seem to have picked up on this possibility - but that's maybe because his article was about sensor failure modes (depends at what point he picked his title I guess).

An intermittent wiring or connection fault, at or near the sensor, could account for the issues that triggered the sensor replacement and the worsening of the problem after it was replaced. If it is vibration triggered then ground testing might fail to find it (and the AOA sensor might test out fine). Be interesting to know if that AOA sensor had been replaced before or was factory fitted.
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