A320 engine anti ice usage..

[IFLY_INDIGO]

hi there, AFM says "do not rely on airframe visual icing cues for turning on the engine anti ice on. use the temp and visible moisture crieteria"

I don't agree with that.. If there is no icing on wipers or near wipers or on ice detection probe, how could there be icing on engine nacelle?

can anyone explain better?

[PantLoad]

Please don't do that....Please follow your SOP.

The Flight Crew Training Manual (FCTM) has an excellent section on this.


Fly Safe,

PantLoad

[Dani]

I think you are confusing icing condition for use of Engine Anti-Ice with Airfoil Anti-Ice.

There is probably no aircraft in the world where you wait until you have Ice until you hit the Engine Anti-Ice button. You want to be safe, remember AUA F70 in Munich with double engine failure (for other reasons, ok).

Airfoil Anti-Ice (also called Wing and Tail Anti-Ice) uses much more engine energy (bleed air), so you want to wait with that a bit longer. You only use it when you have actual ice on your Ice indicator (can be an mechanical-electronical devise or your eye).

hth,
Dani

[TO MEMO]

IFI... please don`T do that!

Conditions at the engine nacelle, are way diferent than those at the wing leading edge, wipers and ice detector! Due to engine suction, the pressure and temperatures are lower. We would have to do some calculations or measure it for real, so lets just guess some numers. For instance if you have a TAT 9ºc, at the engine nacelle you might have, lets say, -5ºC.

Remember... if it is written in the manual... it`s true! more it`s sacred!

Fly safe

cheers

[PA38-Pilot]

It is called engine ANTI ice for a reason (and not DE-Ice). It is made to prevent ice, not to get rid of it.

[Gary Lager]

There can quite often be ide build up on the leading edge with none apparent on the indicator. Also since the ice detector isn't de-iced, after you've used the WAI the two situations no longer correspond, even if they did in the first place. I prefer to look out of the window for WAI use.

EAI - follow the SOP, if you don't understand why, then you're not qualified to start coming up with your own bright ideas!

[lomapaseo]

Lots of good advice above (other than the original poster):)

Just to add some comments.

It's important to understand or at least accept the differnce beween ice forming in engines or naceles where pressure reductions at low fan power reduce the apparant temperature and allow ice to initiate much sooner than windscreens.

Also for the most part engine anti-ice typically refers to the inlet since very few engine now-a-days bleed the warm air into the engine itself, preferring instead to use the effects of windage or centifugals off the spinning blades.

And to be technically strict, many points in the certified icing envelop will still generate ice on engine and inlet related surfaces so the so-called anti-ice simply limits the amount of build up (before shedding to something that won't be noticed in the flight deck or otherwise damage the engine.

[IFLY_INDIGO]

thanks everybody... i am convinced... will follow SOP...

thanks in making me more safer...

[goeasy]

Okay, slightly different angle..... How much 'visible moisture' do you wait for before usung EAI?

Thin cloud layers? i.e 50/100ft ... see through?
Lowish vis but not cloud?

I am just curious about moisture, not precipitation. Some refs quote vis below 1500m before ice will stick...

[PantLoad]

1 Statute Mile or less

[FlightDirector7]

Hi All,

I have a couple of questions regarding use of ENG/WING anti ice and CONTINUOUS IGNITION which i would appreciate some clarification on.

Q1. Where can i find the increase in fuel consumption with the use of ENG/WING anti ice ? I have tried looking everywhere in the FCOM's but i just can't seem to find anything appropriate. I have tried some experiments while flying on fuel consumption per minute. but it didn't turn out conclusive.

Q2. Many people i fly with don't seem to use WING anti ice when passing icing conditions but only use ENG anti ice. Is there a bigger penalty on fuel or is there any other explanation ??

[dkz]

FD7, Q2:

The Wing anti-ice is recommended when you have any ice visible, in standard icing condition (+10/-40 like in ENG Anti-ice) there is no need for Wing A/I.

[lomapaseo]

Q2. Many people i fly with don't seem to use WING anti ice when passing icing conditions but only use ENG anti ice. Is there a bigger penalty on fuel or is there any other explanation ??

Wing ice accretes about the same way that windshield wiper ice does which is a visible sign that you are in icing conditions in-flight.

Engine ice can accrete behind the fan blades (due to low workload in the compressor) and is not visible. Furthermore the sucking of the air at low power conditions further depresses the temp in the front of the engine at low power conditions and results in the freezing point being reached before the outside air temperature at the windshield..

Now add to this the much greater concentration of water inside the engine again due its capture at low power and once you reach the freezing point it accretes faster than the visible windscreen.

In the case of icing, flight safety far outweighs fuel burn penalty and thus the FCOMS are written arround that concern.

[aulglarse]

FD7, trying to answer to Q1: In Flight Performance FCOM Section 3.05 and 3.06 covering various flight phases/scenarios.

Tables show additives for engine anti-ice on and total anti-ice on for time, fuel, distance and TAS.

There is similar info in the QRH 4.06.

Hope this helps.