Automatic operation of wing anti-ice

[Don t moderate me this way 882]

While the operation of engine anti-ice in the T7 seems rather straightforward and intuitive to me, the T7's wing anti-ice (in 'AUTO' mode) kinda puzzles me:

 

If WAI activates, it operates only for about one or two seconds just to switch off after that short period automatically. Isn't a system like that supposed to work during longer periods of time in order to affect any structural icing?

 

And just in case someone like ... myself will read my post  (you know what I mean: the 'RTFM' type of guy ... ): I checked the documentation but didn't really find the decisive hint (yes, all the documentation - the pdf search function was my best friend ... but didn't quite delivered the answer. B))

 

Thanks for bothering!!!

[tcas_climb 45]

I've noticed the same behavior when I set it to ON during initial climb out a few days ago. It cycled on and off about 2 or 3 times then came on steady, all while the tat was around 6 degrees.

[777simmer 117]

Cant help much here I am afraid :-(

 

12 years on the 777 and I have yet to see the Wing Anti Ice become activated automatically!

Engine anti ice yes.....but wing not.

 

I was told the 777 is not really prone to pick up wing ice due to its (aerodynamic) design and Boeing initially intended to not equip the 777 with Wing Anti Ice equipment at all!

[Don t moderate me this way 882]

Cant help much here I am afraid :-(

 

12 years on the 777 and I have yet to see the Wing Anti Ice become activated automatically!

Engine anti ice yes.....but wing not.

 

I was told the 777 is not really prone to pick up wing ice due to its (aerodynamic) design and Boeing initially intended to not equip the 777 with Wing Anti Ice equipment at all!

 

 

Thank you, Rob, for confirming that WAI is a rare occurrence on the T7. It's rather hard to trigger in FSX; it takes some very special wx conditions for it to activate.

 

But when it engages, it's just a short "boost" of WAI, automatically switched off again after maybe 2 seconds. And neither the docs nor the web can really help explaining ...

[CaptCraig 226]

I've been leaving all knobs in auto thinking it would manage automatically.  So I should be turning on AI below 10C like every other plane? 

[tcas_climb 45]

I've been leaving all knobs in auto thinking it would manage automatically. So I should be turning on AI below 10C like every other plane?

Auto is fine, but according to the fcom, auto for the engine anti ice does not work on the ground, so it should be manually selected on until you are clear of icing conditions, and of course you know, wing anti ice does not work on the ground regardless of switch position.

[FLEX1978 373]

Could this not be a potential bug? Bryan is correct in saying WAI does not work on the ground. If you do select WAI it will turn on briefly just to do a self test, it will then automatically disengage.

 

If icing conditions are setup in the sim, and the aircraft is airborne, wing anti ice should remain on.

 

Edit - Should also add that even if SAT is below 10c icing conditions doesn't necessarily exist, visible moisture also needs to exist, fog/rain/clouds/snow

[Don t moderate me this way 882]

Could this not be a potential bug? (...)

 

 

Like in : "WAI in the air is mistakenly modelled in the same way as WAI on the ground is supposed to work?"

 

Sounds plausible to me, Rob ...

 

 

 

@Ryan:

Can we get a ground/air switch, pls.?  

[FLEX1978 373]

Like in : "WAI in the air is mistakenly modelled in the same way as WAI on the ground is supposed to work?"

 

Sounds plausible to me, Rob ...

 

 

 

@Ryan:

Can we get a ground/air switch, pls.?

Yes possibly... Then again, perhaps the system also does a self test in auto whilst airborn if no true icing conditions are detected.

 

Have you tried setting the sim up in freezing rain? Put the aircraft in a holding pattern at low altitude, set heavy rain and SAT to something like -5, see what happens in auto whilst the aircraft is in a clean config

 

Regards

[Don t moderate me this way 882]

Bug or no bug?!?

 

It starts with a period of ice accumulation ("ice weight" in FS Captain) with WAI off:

 

 

 

Next is a brief activation of WAI. You hardly notice the arrow indicator changing to green; it's almost "just" the valve indication (different for the EAI):

 

 

 

Now, that's really interesting: That very short period of WAI hardly having been on is enough for FS Captain to reset its "ice weight" to zero (and to start accumulating ice all over again):

 

 

 

FS Captain indicates that "WAI on" time is "sufficiently" modelled on the T7 - is this brief activation of WAI a bug at all???

[FLEX1978 373]

Looks to me like the PMDG 777 WAI logic is correct

[777simmer 117]

Interesting,

 

That CDU is provided by FS Captain?

Does it replace the 777 CDU completely?

 

I will have a look later today at wing anti ice here and see what is does.

[FLEX1978 373]

Interesting,

That CDU is provided by FS Captain?

Does it replace the 777 CDU completely?

I will have a look later today at wing anti ice here and see what is does.

No, the CDU just adds additional functions like ACARS and whole bunch of stuff. The addon is designed as a generic CDU. Check out the fscaptain website, they add quite a lot to the sim that enhances the realism.

[777simmer 117]

 If WAI activates, it operates only for about one or two seconds just to switch off after that short period automatically. Isn't a system like that supposed to work during longer periods of time in order to affect any structural

I looked into the (official) Computer Based Training we have. All is sais in there is:

 

Two fuselage side mounted Anti ice probes are mounted on the nose.

If a probe picks up ice, both probes will heat up in order to de-ice.

This is called an icing cycle.

 

Engine Anti ice is activated soon after ice is detected.

Wing anti ice is activated after several cycles! (so the probe must pick up ice again and again for the wing anti ice system to activate)

(We are talking Auto mode ofcourse!)

 

Once Engine and/or Wing anti icing is automatically switched on, the detection system does not stop detecting!

The probes keep going through their icing cycles and both Engine and Wing anti ice are not turned off untill no more ice is detected for several minutes (I dont know how many minutes).

 

 

So, yes it is supposed to work longer than just a few seconds!

[Spam3d 54]

The probe oscillates at a certain frequency, when ice builds the extra weight changes this frequency and indicates that ice has accumulated, then the WAI is activated. It must use this as its reference for the activation and de activation.