PPRuNe Forums - View Single Post - AF 447 Thread No. 9
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Old 20th Aug 2012, 17:01
  #1444 (permalink)  
OK465
 
Join Date: May 2011
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...but HN39 showed that as long as the elevators are not full nose-up, this wouldn't change anything.
AZR:

May I just say one more thing about this so I don't mislead anyone who
actually does this for a living.

HN39 is entirely correct 'theoretically'...

but in the current embodiment of Alternate Law, when a THS 'jam' (STAB CTL FAULT) is in effect from either holding the trim wheel or inserting the failure, you will also eventually see triple PRIM PITCH faults.

Under circumstances where the Stab is available, triple PRIM faults put you in Direct Law and advises to Use Manual Pitch Trim.

If the condition is entered as a result of the THS fault, you also effectively end up in Direct Law when the PRIMS fault as a result of the Stab 'jam'. However no message to Use Manual Pitch Trim appears, for obvious reasons.

From this point, as speed changes, the pilot has to make SS inputs to maintain a given flightpath, as opposed to Alternate Law WITH autotrim where the flightpath can be maintained 'hands off'. Manual SS inputs generally do not produce the precise flight path control that automated inputs do.

(Whether or not the stall would have developed in either case or have been less likely with a fixed THS is entirely speculative and a matter of opinion.)

That is the difference.

Last edited by OK465; 20th Aug 2012 at 17:11. Reason: italics
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