Anti-Ice - utilization

[Hardy Heinlin]

In BA with the manual system we didn't have a NO ICING message.

Does BA have both auto-NAI and auto-WAI?

What if it's a mix of manual and auto?

[andrej]

Thank you to all - very informative - replies. It is very interesting topic.

Best!

[Mariano]

Up until recently, our company manuals stated that on GE CF6-80C2 engines, engine and wing anti-ice was to be on at or below 22,000 feet and prior to reducing thrust for descent while in visible moisture with TAT less than +10C, including SAT less than -40C.

Apparently, this extra bleed request helped slow down the rate of ice accretion on the booster stages of the low pressure compressor.

Once updated, a new ECU software increases the engine's resistance to flameout by modifying the variable bleed valve schedule in order to increase ice extraction from the core flight path, negating the need to activate wing anti-ice.

They have since amended our manuals to state that wing anti-ice activation is required at or below 22,000 feet with thrust reduced for descent, only while in ice crystal icing conditions (and not every time while in "regular" icing conditions). The 747 fleet also includes a note stating that even if in ice crystal icing conditions at or below 22,000 feet, once flaps are extended, wing anti-ice selector can be placed in the OFF (or AUTO) position.

I don't know which carriers or fleets have the upgraded software, or whether it is mandated, but I assume that it must be widespread by now.

I have read and heard that the 747-8 engines are also quite prone to ice crystal icing, and that an updated ECU software has been implemented as well.

Experts please chime in.

Regards,

Mariano

[Britjet]

Hardy - BA only had the manual system.
Peter

[Hardy Heinlin]

Ah, so the >ICING and >NO ICING messages are not installed in all manual systems.

The method we used (in manual) was to switch it on for a minute or so, every time an EICAS message appeared.

Which EICAS message?


|-|ardy

[Britjet]

@Hardy.
ICING WING.
Peter

[Hardy Heinlin]

OK, we have these two messages in PSX:

>ICING WING   (advisory)
>ICING NAC ()  (caution)



When optionally those are enabled:

>ICING
>NO ICING

... then I guess the >ICING WING and >ICING NAC messages have to be disabled.


I see three logical pairs of "activate-anti-ice" versus "deactivate-anti-ice":

>ICING WING  versus  >ANTI-ICE WING

>ICING NAC  versus  >ANTI-ICE NAC

>ICING  versus  >NO ICING

The only difference being the latter pair doesn't refer to anti-ice status; it needs to be cleared by the cancel button.


|-|ardy



I just noticed Steve's BA model files have manual WAI and auto NAI, i.e. mixed systems. (By "mixed" I meant mixed within an aircraft, not within the BA fleet.)

[dhob]

Up until recently, our company manuals stated that on GE CF6-80C2 engines, engine and wing anti-ice was to be on at or below 22,000 feet and prior to reducing thrust for descent while in visible moisture with TAT less than +10C, including SAT less than -40C.

Apparently, this extra bleed request helped slow down the rate of ice accretion on the booster stages of the low pressure compressor.

Once updated, a new ECU software increases the engine's resistance to flameout by modifying the variable bleed valve schedule in order to increase ice extraction from the core flight path, negating the need to activate wing anti-ice.

They have since amended our manuals to state that wing anti-ice activation is required at or below 22,000 feet with thrust reduced for descent, only while in ice crystal icing conditions (and not every time while in "regular" icing conditions). The 747 fleet also includes a note stating that even if in ice crystal icing conditions at or below 22,000 feet, once flaps are extended, wing anti-ice selector can be placed in the OFF (or AUTO) position.

I don't know which carriers or fleets have the upgraded software, or whether it is mandated, but I assume that it must be widespread by now.

I have read and heard that the 747-8 engines are also quite prone to ice crystal icing, and that an updated ECU software has been implemented as well.

Experts please chime in.

Regards,

Mariano

The FAA issued Airworthiness Directive 2011-16-02 August 30th, 2011 for the 747- 400 requiring the following procedure to be added to the AFM (and FCOM): "Prior to reducing thrust for descent in visible moisture and TAT less than 10 °C, including SAT less than -40 °C, nacelle anti-ice switch must be in the ON position. At or below 22,000 ft, wing anti-ice selector must be in the ON position. When these icing conditions (visible moisture and TAT less than 10 °C, including SAT less than -40 °C) are no longer present or anticipated, place the nacelle and wing anti-ice selectors in the OFF (or AUTO) position." Operators with 8.2P1 EEC software on all airplanes did not need to use wing anti-ice (above or below 22,000 feet) in this procedure.

In July 2013, The Boeing Company requested approval (via an AMOC) that the Ice Crystal Icing non-normal checklist maintains an acceptable level of safety with regard to FAA AD 2011-16-02. In August 2013, the FAA approved Boeing's request.

Current Boeing FCOM Operating Instructions: When engine ice crystal icing or TAT probe icing is suspected, do the Ice Crystal Icing non-normal checklist published in the April 1, 2014 FCOM/QRH revision. This non-normal checklist is in accordance with the AMOC to AD 2011-16-02.

The 747-8 GENx engines were more susceptible to ice crystal icing at entry into service. The FAA issued AD 2013-24-01 that essentially prohibited flight within 50NM of amber or red radar returns that are displayed below the airplane's flight path above 30000 feet. With Electronic Engine Control EEC software version C075 or later, and GE Service Bulletin 72-0241 or production equivalent (a mechanical modification to the fan hub stator assembly BOGV) is installed on all engines, the 50NM restriction is no longer applicable.

[Mariano]

Thanks for the added clarity, dhob.

Best regards,

Mariano

[John H Watson]

Airplanes with the Manual anti-ice system have one ice detector installed on the left side.

If you were lucky. I think only one or two of our manually anti-iced aircraft had a sensor. The ones that did were bought from another airline. No sensors...no messages. Anti-ice was applied as deemed necessary.

I recall, for simplicity, all PSX aircraft were fitted with at least one ice detector to generate messages.

I can confirm on our single detector (i.e. manual anti-ice) aircraft, the only messages were Advisory messages  >ICING and >NO ICING... and a status message "ICE DETECTOR".

[Hardy Heinlin]

I'll try to implement those ICING messages in the next PSX update (for models with manual control).

I've changed my mind. I won't :-) Too little info; would be too much work on vague background. Maybe later.


|-|ardy