Why does A330 with emergency config will enter direct law after L/G gravity extension

[can8]

Hello everyone

Currently I'm in transition course from A320 to A330. I'm a bit confused about the difference A320 and A330.
In A320 (the old version, I noticed the new one with winglet has different law reversion), whenever we put the L/G gravity extension, the A/C has to enter the direct law.
However, in A330, although for many cases even we lower the gear with L/G gravity extension, it could still stay in Alternate law. I think just like the new A320 with the winglet. It quite makes sense that a new generation A/C could tolerant more failures.
Except in Emergency ELEC Configuration. It will still enter the direct law after we lower the L/G gravity extension. I also check the Land recovery pb function, but still unable to find out why it will enter the direct law. Could someone please explain to me? Very appreciate!

[Rocket3837]

Helo,
Is any RAD altimeters operative in A330 Emer Elec Config?

[can8]

Nope. But as Dual RA failures in A330, it will enter flare mode rather than direct law for A320 when our L/G down provided AP is OFF.

[vilas]

can8
I remember reading in one airbus instructor meeting report that A330 is not a big A320. So I think it will be better to forget A320 during transition. A330 has better redundancy the flare mode and also the AP is available in some situations in alternate law. But in A320 the transition to direct law with gear down is in fact the only flare mode of alternate law. The flare mode of A330 is slight pitch down elevator is applied while in A320 it progressively pitches down by eight degrees. But without Radio altitude measurement there can be no flare mode any way so with gear down it goes in direct law. A330 also does the same in ELEC EMER. That is why you use manual pitch trim. Do not confuse this with A320 Neo not going to direct law with only some failures like double yaw damper fail. Actually it does not even go into alternate law but remains in normal law with flare mode. Airbus wants pilots to carefully handle since there is a failure so only the indication of alternate law is displayed. As I said if you keep comparing A320 you will add to your confusion.

[vilas]

But as Dual RA failures in A330, it will enter flare mode rather than direct law for A320 when our L/G down provided AP is OFF. It is same thing. This flare mode is like A320 direct law where the nose pitches down when you flare and reduce thrust.

[Sidestick_n_Rudder]

It is quite confusing though. The 330 EMER ELEC procedure says the A/C will enter Direct Law upon L/G ext., whereas RA 1+2 FAULT procedure says it will enter Flare Law upon L/G ext. What's the difference between those two? Both cases say "MAN PITCH TRIM...USE"

[vilas]

It's the same thing. They could have avoided the confusion by using the same terminology.

[Sidestick_n_Rudder]

How about roll? In Direct Law, the roll control is direct. How about the Flare Law in case of both RA failure? I think it will stay in Roll Normal Law. Maybe that's why they use different terminology?

[can8]

Hi Sidestick n Rudder
I agree your opinion about the Roll stay in Normal law while in Flare mode since I've read this in somewhere of this forum. You could check it out when you have time.
Hi Vilas
Thanks for your reply. I do agree I have to forget something to avoid confusing me too much. Normally I could forget very well ha ha!
Just a minor correction, in A320, at 30 feet the direct law will lower down the pitch to -2 degree over 8 sec. Not 8 degrees. It will be too much I guess!( I could not remember this, I just check the FCOM)
Cheers!!

[Romasik]

Wondering what's the practical use of this discussion? There are millions of issues like this in Airbus. You will freak out trying to find reasons behind all of them. Just follow the procedure. It was designed this way. To go through CBT, FTD, FFS and fly it next day with passengers. Sure, over time we come across usefull things. But in this case I don't think knowing the reason why the aircraft goes into Direct Law will help you in any way. To remember that it goes Direct? It's written in the QRH or on the screen!
We have so many other thing to know and remember.

[Denti]

o not confuse this with A320 Neo not going to direct law with only some failures like double yaw damper fail. Actually it does not even go into alternate law but remains in normal law with flare mode.

Isn't this behaviour/upgrade associated with the sharklet versions instead of the NEO? We do not operate it (yet) but do have a few aircraft that have that kind of behaviour.

[vilas]

My mistake. Yes it is with sharklet aircraft.

[vilas]

Romasik
I don't agree with you. Although it is an easy aircraft to fly a pilot is not a button pushing Zombie. AOA blocked Valpha protection was not there on ECAM or QRH it was the knowledgeable smart pilot who did it to save the situation. That's what separates average pilot from the extraordinary.

[Romasik]

I'm mostly talking about this particular issue. Knowing the reason of going direct won't make you an extraordinary pilot. There are tonnes of other things that we have to know and refresh from time to time. This is much more practical. It's difficult to draw the line between usefull and useless stuff.
BTW, the idea of gettig rid of protections normally comes to most pilot minds when they start studying it.

[vilas]

If you don't have the attitude to question then how come you thought about getting out of protections? It is good to know and share information. It gives one the confidence about the machine you operate.

[vilas]

can8 ko
Correction. The pitch before flare is +4 degrees from there it goes down to -2 degrees so total pitch down is 6 degrees and not 8 degrees as I said. A330 has two flare modes when out of normal law. In ALT1 it has flare mode in which roll is normal only pitch is direct stick to elevator and when in ALT 2 it is like A320, landing gear down direct law. In dual RA fail, inability to read radio altitude is the only problem so it uses the ALT1 flare mode. When in ELEC EMER since there are many inop systems that is not possible. So it reverts to complete gear down direct law. In both these cases the nose down pitch comes from speed reduction and the thrust reduction during flare. The FCS does not apply any nose down elevator.

[CaptainMongo]

I agree with Vilas - both depth and breadth of knowledge is important.

As an instructor in the USAF and now check airman at my airline, I have never answered a students question with, "That's not important, you don't need to know that." The more insightful the question, the better the student.

The relevant question: "How do we make ourselves and our pilot group better?" This forum most certainly has made me a more knowledgeable pilot. I read replies to questions I would never have thought to ask.

[vilas]

As they say "There are no stupid questions only stupid answers".

[Concours77]

So, hoping this is not stupid....

If the A330 is in distress of some description, and crew wanted Direct Law, would selection of L/G in emer. Config be a solution? Instead of disabling two ADR?

ducking.....

[vilas]

Firstly switching off two ADRs doesn't get you in direct law second there is no distress that is relieved by direct law. It is a temporary situation to give you natural aircraft behaviour for flare and landing. Since there are no stupid questions you don't have to duck.

[Romasik]

can8 ko
Correction. The pitch before flare is +4 degrees from there it goes down to -2 degrees so total pitch down is 6 degrees and not 8 degrees as I said. A330 has two flare modes when out of normal law. In ALT1 it has flare mode in which roll is normal only pitch is direct stick to elevator and when in ALT 2 it is like A320, landing gear down direct law. In dual RA fail, inability to read radio altitude is the only problem so it uses the ALT1 flare mode. When in ELEC EMER since there are many inop systems that is not possible. So it reverts to complete gear down direct law. In both these cases the nose down pitch comes from speed reduction and the thrust reduction during flare. The FCS does not apply any nose down elevator.
This is another example. Don't take me wrong. I'm aware about the value of knowlege. The question is: to what extent? Going from time to time through official books just to have a general idea and to be able to quickly find information when you need it and keeping up with revisions, takes too much time and memory. On top of it you suggest things that not even in "nice to know" category, but simply useless (IMHO). What exactly from information in your quoted phrase helps you to fly the aircraft and how? Just curious. And I'm ready to accept it if it's reasonable. I have to admit I only remember that aircraft applies pitch down when I read disscusions like this. 6 years. About 10-15 landings per month. I have never thought about it. Just reacting on what aircraft, wind or sometimes another pilot are doing.

[Rocket3837]

So it reverts to complete gear down direct law. In both these cases the nose down pitch comes from speed reduction and the thrust reduction during flare. The FCS does not apply any nose down elevator.
Vilas,
Does the computer in A330 do pitch down during flare mode in normal law?

[vilas]

Rocket
I stated the flare mode of A330 is slight pitch down elevator is applied. It is from FCOM.

[pfvspnf]

Been flying the 330 for sometime now and you can barely feel this pitch down effect.

@Romasik, point taken in knowing all of this wont help with the hand flying but a good background on the failure would certainly help in the overall decision making process.

[Rocket3837]

Hi vilas,
I thought the "pitch down" is a special feature in A320 family only and not for the other widebodies (A330&A340....)....
I am sure the "Pitch down" isnot on A340 but I will read the FCOM for the A330.

Many thanks

[pfvspnf]

At 50 ft slight pitch down , says so in the FCOM for the A330/340

[PilotJames]

can8
I remember reading in one airbus instructor meeting report that A330 is not a big A320. So I think it will be better to forget A320 during transition. A330 has better redundancy the flare mode and also the AP is available in some situations in alternate law. But in A320 the transition to direct law with gear down is in fact the only flare mode of alternate law. The flare mode of A330 is slight pitch down elevator is applied while in A320 it progressively pitches down by eight degrees. But without Radio altitude measurement there can be no flare mode any way so with gear down it goes in direct law. A330 also does the same in ELEC EMER. That is why you use manual pitch trim. Do not confuse this with A320 Neo not going to direct law with only some failures like double yaw damper fail. Actually it does not even go into alternate law but remains in normal law with flare mode. Airbus wants pilots to carefully handle since there is a failure so only the indication of alternate law is displayed. As I said if you keep comparing A320 you will add to your confusion.

Sorry Vilas would you mind please explaining the dual yaw damper failure regarding the control laws in a sharklet aircraft?
I had a look in my manuals and don't see any differences?
Cheers

[Denti]

The sharklet aircraft do not go into direct law with gear down. They stay in "alternate" law which is actually normal law in this case. Compare the FCOM side by side for a non sharklet and a sharklet aircraft, FCOM-PRO-ABN-22-AUTO FLT YAW DAMPER SYS. The sharklet aircraft omit the line WHEN L/G DN: DIRECT LAW.

[PilotJames]

Oh yes I see thank you.
You say it stays in alternate law which is actually normal law. Would you have the amber crosses indicating alternate law?
But normal flare law is available?

[vilas]

Pilot James
The sharklet aircraft has better maneuverability so it retains normal law with yaw damper 1+2 and two other failures while normal A320 would go in alternate law and gear down direct law. But since There is a failure Airbus wants pilots to be careful so only indications of alternate law are shown but aircraft is in normal law and normal flare mode is available. This one is also of the many replies I obtained from Airbus.

[PilotJames]

Thank you Vilas that's great, worth knowing as I fly these regularly.

[vilas]

It is also applicable to three other failures i.e. FAC1+ FAC2
FAC1+YELLOW and FAC2+ GREEN.

[aguadalte]

When in EMER ELEC CONF, on the A330, the LANDING GEAR must be extended by GRAVITY (and Nose Wheel Steering is LOST in all cases) in order to avoid strong fluctuation of the G HYD pressure, which may cause spurious disconnection of the EMER GEN, when it is powered by EDP.

[aguadalte]

The reason why the aircraft enters Direct Law when LNDG GEAR down by Gravity is because of the need for using of LAND RECOVERY (to energize ILS 1, SFCC 1, LGCIU 1, BSCU 1, and WHC 1). This, will disconnect the EMERG GEN and will put electricity on BATs only.

[Fursty Ferret]

.The sharklet aircraft has better maneuverability so it retains normal law with yaw damper 1+2 and two other failures while normal A320 would go in alternate law and gear down direct law.

The cynic in me wonders whether a sharkletty aircraft might be an absolute nightmare to fly with the loss of both yaw dampers, hence the increased redundancy.

[Alloy]

I understand all A321 aircraft, including early versions, also did not have the problem of reverting to direct law on gravity gear extension due to the extended nose gear not disturbing the airflow around the RAT and thus the RAT keeps running. I don't know if this is the case with early A318/319s?

[vilas]

What I stated is only true for A320/321. It is not tested for A319 yet. There is no increased redundancy. Had it been so Airbus cannot hide it. They will rather publicize it.

[can8]

Hello guys

Kinds of busy last week! Very appreciate so many back and forth Q & A. I could see not only me but also other one could learn something from this discussion! It's more than my expectation!