Airbus use of engine anti-ice

[jetjoker]

After reading the Airbus FCTM section on ICE CRYSTALS and how they may have an adverse effect on the aircraft, I am surprised to see how there is no suggestion at all to use engine anti-ice to protect the engines when unable to avoid these conditions.

There are many documented cases in which aircraft engines have been affected and I would think using engine anti-ice would be a sensible thing to do even if the temperature is below the icing conditions range (10C to -40C in cruise).

In the FCOM under normal procedures, IN FLIGHT.. just below the note "In the climb or the cruise phase, when the SAT goes below -40C, the flight crew should turn off the engine anti-ice."

you can read.."If the flight Crew does not apply the recommended anti-ice procedures, engine stall, over-temperature, or engine damage occur."

Why is Airbus using SAT -40C as a limitation for the use of engine anti-ice in cruise regardless of flight conditions.

Any comments on this?

[vapilot2004]

Ice crystals generally affect the engine core and do not collect on the cowl inlet, which is fed hot air when the anti-ice is selected ON. The use of continuous ignition would seem prudent, however.

[maggot]

Not just airbus RE the -40 parameter...

[tdracer]

Cowl Anti-Ice is in-effective against Ice Crystal Icing (ICI).
On the CF6-80C2, Boeing has recommended the use of anti-ice for ICI because the increased engine bleed helps make the core less susceptible to flameout if ICI results in a large ice shed, not because heating the inlet will prevent ice accumulation - if anything heat makes things worse in ICI.

[Goldenrivett]

Why is Airbus using SAT -40C as a limitation for the use of engine anti-ice in cruise regardless of flight conditions.

Cold dry ice won't stick to the airframe / engine cowl on impact. Super cooled water droplets will stick to airframe etc. on impact.
Supercooled water droplets don't normally exist below -40C. The exception is in cumulonimbus clouds. (not enough time yet for the supercooled water droplets to nucleate.) See https://www.skybrary.aero/index.php/Supercooled_Water_Droplets

Most (all?) manufacturers don't recommend using engine anti-ice at -40C and below. With engine anti-icing on you might even warm ice crystals at say -65C up to the partial melting point and make the crystals sticky again.

[FlightDetent]

Slight drift: where in Airbus FCOM does it say these days that in vicinity of CB's + in cloud the E-AI should remain on even if SAT is less than -40 deg C?

Thanks, I did search for the (similar) phrase and came up with no results. Or was it never there?

[lomapaseo]

some additional information

caution, I'm not sure this is totally responsive to the OPs questions


https://www.wired.com/story/testing-boeings-new-engine/

excerpt follows
.... You might think the planet’s biggest engine runs hot enough to vaporize any ice bold enough to get near it. In fact, apart from the core, most of the engine is cold...

The basis of the engine design is not to exclude ice formation, but to make it tolerant to any ice that may form within it's innards.

[Goldenrivett]

where in Airbus FCOM does it say these days that in vicinity of CB's + in cloud the E-AI should remain on even if SAT is less than -40 deg C?

I don't think it does. However this Airbus document "Getting to grips with cold weather operations" https://skybrary.aero/bookshelf/books/3404.pdf, on page 40 says:

"The engine ice protection system (Nacelle Anti-Ice: NAI) must be immediately activated when encountering the above-noted icing condition. This procedure prevents any ice accretion (anti-icing) on the air intakes of the engines, thus protecting the fan blades from damage due to ingested ice plates (FOD). When the Static Air Temperature (SAT) is below -40°C the NAI must only be ‘ON’ when the aircraft enters cumulonimbus clouds, or when the Advisory Ice Detection System - if installed - annunciates ICE DETECTED (refer to section A3.3)."
(my bolding)

[jetjoker]

All correct and very informative answers..

Thank you Goldenrivett, as you pointed out, the only reference to the use of engine anti-ice when SAT is below -40 degrees is in the Airbus "getting to grips with COLD WEATHER OPERATIONS"

When you are crossing the Equator in an area of high MORA at FL380 in cloud through a line of embedded CBs with tops up to FL520 in heavy precipitation and a SAT of -44 degrees, knowledge and common sense must prevail.

The -40 degree limit for using engine anti-ice in cruise is chosen "because practically no supercooled water might be present at colder temperatures" (reference from the same manual)