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Old 30th January 2015 | 12:28
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safetypee
 
Joined: Dec 2002
Posts: 2,776
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From: UK
arcdu, Wageslave, take care in relating what a simulator might do and a flight assessment based on previous knowledge that an imbalance exists.
I recall a 737 incident many years ago (UK AAIB ? – looking for the report), where fuel ‘mismanagement’ – fuel transfer remained open, resulted in a gross fuel asymmetry. The autopilot was in use with FMS input; the crew noticed poor track keeping / failure to turn at a waypoint. On disconnecting the AP the aircraft rolled 120 deg before recovery.
One aspect of the surprise was that the crew attempted to zero the roll stick positon / force vs the opposing force to achieve wings level. Few crews are familiar with flying ‘out of trim’, particularly in roll, where although the sick positon / force and control demands are relatively low / easy to handle, the situation is so unfamiliar it conflicts with the norm – ‘cognitive dissidence’.

I used that example as guidance in flight tests, together with a 4 sec pilot intervention recovery delay (cruise) from an inadvertent AP disengagement – a double failure, but its guidance. My aircraft also had an AP roll demand limit light, whereas I recall that some versions of the 737 only had ‘torque’ indicators or nothing at all.
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