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Old 14th Apr 2011, 15:20
  #3483 (permalink)  
PJ2
 
Join Date: Mar 2003
Location: BC
Age: 76
Posts: 2,484
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CONF iture;
I have never had or thought to reset such computer unless specifically requested by ECAM or QRH.
Yes, fully agree - it is a serious matter that requires some careful thought and action.
If at the time of the automatic disconnection of the autothrust with activation of the thrust lock function, the A/THR had lowered the EPR to reduce the speed to the selected mach for turbulence, it is possible that the N1 were in a lower range than usual for cruise
Selecting the turbulence penetration speed on the FCU would not reduce the N1 into a low range.

The cruise N1 for M0.82 would be around 86%. The turbulence penetration speed at FL350 is 260kts, (M0.78 @ FL370) and the power setting is 76%.

Setting 260kts in the FCU speed window may initially reduce the N1 below the 76% and as the speed was achieved would return to the target setting but any reduction would not be in a 'low range', nor would a disconnection (caused by system problems) leave the aircraft at risk.

Sometimes in mountain wave conditions where the speed is increasing, the A/T will reduce the N1, sometimes even to idle if the Mach is getting close to VMO/MMO but for a twenty to twenty-five knot reduction the N1 would not reduce into what could be called "low range". Even if it actually did, it takes a long time to lose enough speed to be at risk.

The thrust lock function is easily handled using manual thrust, (move the levers to set 76%). The severe turbulence penetration drill states that the A/T should be disconnected if speed variations are large.
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