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-   -   A320 protection (https://www.pprune.org/tech-log/585639-a320-protection.html)

Bkdoss 13th Oct 2016 02:21

A320 protection
 
A320 as we know has a lot of protections that manages to keep the aircraft within the flight envelope whenever the normal law is active. In a hypothetical scenario in which during the approach to land, config 3 being the landing configuration, if inadvertently during go around config 1 ( instead of one up which is config 2 ) is selected, what would be the protection that would kick in? Would the flaps retract ?

whitelabel 13th Oct 2016 03:50

Yes it will go from flap 3 to 1+F. You have A-lock function which prevents slat retraction but that is only applicable when going from F1 to F0. In this case you will most likely (depending on Vls) end up in high angle of attack protection and possibly A.FLOOR.

vilas 13th Oct 2016 05:17

It will not trigger any protection. In heavy weight landing scenario in flap3 approach the recommended procedure is to retract to flap1. As sufficient but less than normal margin exists. During GA you're already in TOGA so no question of alpha floor.

hph304 13th Oct 2016 06:31

Wouldnt it still switch to a.floor and subsequent thr.lock after passing the trigger even though no more thrust than toga is delivered?

BRAKES HOT 13th Oct 2016 07:17

That's my understanding. Alpha floor is based on angle of attack not thrust lever position

vilas 13th Oct 2016 13:43

Since it meets the climb gradient requirement even when overweight the AOA will no reach Valphaprot to trigger that protection. Quoted below from FCTM on over weight go around:

If aircraft weight is above the maximum weight for go-around in CONF 3, landing will be performed CONF 3 (and go-around CONF 1+F). The CONF 1+F meets the approach climb gradient requirement in all cases (high weights, high altitude and temperature).
If a go-around CONF 1+F is carried out following an approach CONF 3, VLS CONF 1+F may be higher than VLS CONF 3 +5 kt. The recommendation in such a case is to follow SRS orders which will accelerate the aircraft up to the displayed VLS. It should be noted, however, that VLS CONF 1+F equates to 1.23 VS1G whereas the minimum go-around speed required by regulations is 1.13 VS1G. This requirement is always satisfied



Stone_cold 13th Oct 2016 13:55

Vilas : You said "already in Toga , no question of alpha floor " . You were challenged on this statement , so answer what was asked.

vilas 13th Oct 2016 14:16

Stone_cold
The original question is what protection it will trigger? The answer no protection will be triggered. Since the thrust is already in TOGA if you are talking about cosmetic triggering, it may provided the AOA is reached which it won't for the reasons mentioned. It happens sometimes in wind shear. And you never seem to contribute anything positive yourself except some diatribes. Why is that? I would love to see some pearls of wisdom from you.

Amadis of Gaul 13th Oct 2016 16:14

I don't see how this is appreciably different from a Config 3 takeoff whereupon we go right to 1+F, and yet we're all still alive.

Stone_cold 13th Oct 2016 20:26

Because you particularly answer definitively as if from a position of absolute authority and I told that I consider you dangerous ! The point is YOU said that if in toga you cannot get alpha floor which is absolute crap! Toga or not has nothing to do with Alpha floor . Is that a sufficient pearl of wisdom !!??

Amadis of Gaul 13th Oct 2016 20:45

Sounds like there is some confusion on some people's part between TOGA lock and Alpha floor....

Bkdoss 14th Oct 2016 02:52

Thanks a ton guys. For the sake of further understanding I'd prefer to rephrase the scenario. I know it's a completely hypothetical scenario, but I want to understand the aircraft's behavior and how it prevents a stall.

Suppose you're on approach with conf Full and selected speeds (not a procedure but a captain on a day decides to) and during go around a novice co pilot retracts the flaps to Config 1. In this case would the speed would revert to SRS mode which will maintain the current speed or Vapp whichever is higher. If this speed is in the Va prot to Va max for the config how would the aircraft react ? Considering that you're already at TOGA how would the aircraft get out of this scenario.

vilas 14th Oct 2016 04:02

Stone cold
Let's play other way around. First you answer the latest questions asked by OP.

vilas 14th Oct 2016 04:53

Amadis of Gaul
Can you explain what is the confusion?

Meikleour 14th Oct 2016 12:28

Stone cold: since you already know - Alpha Floor is an aerodynamically triggered application of TOGA and in a go around TOGA is already applied then what is your bitch with Villas about? A change in the FMA perhaps!!

vilas 14th Oct 2016 13:23

He never takes a chance by answering directly. Enjoys brownie points. This time I am waiting for his answer before replying.

Amadis of Gaul 14th Oct 2016 17:21


Originally Posted by vilas (Post 9540333)
Amadis of Gaul
Can you explain what is the confusion?

You tell me, bud, you're the expert.

vilas 15th Oct 2016 06:59

Bkdoss

FCOM DSC-27-30-20 P 1/4
Before selecting any position, the pilot must pull the lever out of the detent. Balks at positions 1 and 3 prevent the pilot from calling for excessive flap/slat travel with a single action.




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