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Old 27th May 2009, 20:36
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safetypee
 
Join Date: Dec 2002
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I have seen something similar with a modern digital flight guidance system (Honeywell) which disengaged due an ADC comparator trip.
A fault the cross-side interconnect of the ADC static systems resulted in the different static pressures on each side of the aircraft being sensed directly by the ADCs during yawing maneuvers (turbulence ?). If large differences in static pressure are detected, the ADC comparator flags a fault and the FGS/FD disengages.

Normally each ADC will detect its own on-side static, but an averaged value of each side of the aircraft is provided for smoothing and failure cases. Differences in static on each side (i.e. steady heading sideslip/engine failure) are normally averaged (damped) by a cross connection and reservoir. In my instance, there was a fault (leak) in this part of the system which did not affect normal static readings.
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