A-320 Using of Engine anti-ice
 

Hi,

From Airbus Supplementary Techniques:

ENGINE ANTI-ICE must be ON during all ground and flight operations,when Icing conditions exist,or are anticipated,exept during climb and crouse when the SAT is below -40C

ENGINE ANTI-ICE must be ON before and during descent in Icing conditions,even if the SAT is below -40 C

Can anyone explain,why we need to swich ON Engine Anti-Ice during descent in such LOW temperatures ? Thanks a lot :D

Belt and braces I guess, if you are descending the temperature will eventually climb to the level that you will start to get ice problems. As for the bit about turning it on in the descent if icing conditions are anticipated I don't know anyone in our company who operates it like that, what about other operators?. We just turn it on when we are about to enter cloud or rain, doing it the Airbus way I reckon you would have it on most of time in the descent in Europe.

I agree with MAX ANGLE .That´s the way I do.

the stall margin in the descent is that much more critical, ice build up in a low power engine will induce a stall much quicker than one at high power.

of course, should a flame out occur the FADEC will sense a sub idle condition and apply the ignitors automatically together with the relight procedure.

So yes, belt and braces it is!

The descent rule is not intended to require anti-ice in descent outside of icing conditions. Effectively means switch em on just before entering cloud.

As you are moving from a colder to a warmer environment and the nacelle may be cold soaked it is possible to get ice at lower temperatures than you would normally expect since the nacelle may be substantially below the saturation temperature of the air you are flying into.

Same in all jet aircraft. Descent = low thrust, so ice will build up more readily.

We all obviously operate the same, I was taught to read "anticipated" two ways:

1) it is not neccessary to wait until you are in cloud, it is a good habit (read: procedure) to turn EAI on before entering cloud; same logic for climbs in cloud with TAT say +12 deg C;

2) Aniticipate is a good thing, i.e. for TKOF at OAT 4 deg C and cloud base below planned thrust reduction ALT, set EAI on and calculate performance data accordingly, or I personally would not be ashamed to turn EAI for VMC approach to snow covered airfield with precipitation or cloud in the G/A sector (again, low TAT);

I know it's belt and braces and that Airbus recomends it, but in certain airlines this procedure is not employed. Ironically enough, and I subscribe to this myself, putting Antiicing on below -40c can heat up the ice crystals to ABOVE -40c and actually cause Ice to accrue on the fan blades! Interesting eh? Any thoughts ?

whats belt and braces.....:confused:
yeah i sound lost...or stoned...

As found on the internet:

GD&L:ok:

Flight tests (not A320) in recent years identified conditions where engine icing (and possibly airframe icing) can occur outside of the generalised certification boundaries of JAR FAR 25 ‘Annex C’. One area is in very low temperatures, including -40C. A particular problem is with mixed phase icing – a mixture of ice crystals and super cooled water, such that on contact with a surface the water froze acting as glue for the other ice particles. Yet again we learn that the physics of the atmosphere and flight are not as well understood as we thought.
Specific engines / aircraft will have different characteristics and thus different limitations – always stay within the flight manual guidance, but allow some safety margin just in case. Very few aircraft have been flight tested in the range and extent of icing conditions experience during line operations, the certification is based on many assumptions; there is no need for you to be the first to prove the assumptions wrong.

speed brake versus engine anti ice
 

hi, could someone tell me why in the 320 family on the SOP during descent states...
speedbrake..... as req (note: the pilot may use up to half speedbrake when engine anti ice is used )
why is the reason to use half speed breake under this condition?
thanks

half speedbrake provides enough drag to counter the extra idle thrust caused by selecting engine anti ice on.

exactly!

But actually it doesn`t make much difference! Only if you`re using anti-ice for a long period of time you will notice that you`ll need speed brakes.

Do any operators witch on the eng anti ice on at TOD if icing conditions are anticipated? I hope they all do. my company does, and Airbus think it's important, hence the use of the word MUST.

I think it's quite unambiguous - and not open to intepretation!

Anti-Ice vs. De-Ice
 

Gentlemen,

It's important to remember that the engine anti-ice system is just that...anti-ice. Allowing ice to build up could easily cause severe engine damage, flame out, etc. This is why it's important to have the engine anti-ice system ON prior to entering icing conditions.

It does not hurt anything to have the engine anti-ice system ON (if you're anticipating icing conditions), and then discover it really wasn't needed. Yes, you're burning a bit more fuel. But, the other side of the coin is: How much money do you save over the lifetime of your career by damaging an engine? You can buy a lot of fuel for the cost of such an occurrence.

We've beaten this topic to death many times, here, in PPrune. My advice is to follow your company's SOP. It protects you, and, in this regard, it will protect your engines.

I've flown with many guys over the years who have their own 'techniques'. Not a good idea. And, some guys will pretend that, with having their own 'techniques', they employ some degree of piloting proficiency that others lack. WRONG!!!!!

Follow the SOP.

My philosophy...when in doubt (about the possibility of icing) turn on the engine anti-ice. (This covers the 'anticipated' clause of the SOP.)

Another interesting note...some erroneously believe that, under certain atmospheric conditions, turning on engine anti-ice could actually increase the likelyhood of engine flameout and/or damage due to icing. WRONG!!!!!
If this were true, there would be SOPs/limitations regarding this.

When in doubt, use it. The worst-case down-side...you've wasted a bit of fuel.


Fly safe,


PantLoad

Bit of an aside. I'm currently on a Boeing looking at going onto Airbus. Why would half speedbrake be an issue only for autoflight? I can appreciate I've why I've not brought this up in the right place. Though this thread has got my brain cells ticking over.

TG

On the 320 with either AP on, the speedbrakes are limited to half deflection regardless of the handle position.

I understand that bit ok. Just cant understand why?

It's an Airbus I suppose....!

TG

Without the speedbrake restriction the VLS (lowest selectable speed) would increase dramatically if attempting full speedbrake during an emergency descent at altitude. As VLS increased it could cause the AP to trip off as the AoA protection function became active, clearly not what is best right in the middle of an emergency descent!!