Use of Anti Icing

[[email protected]]

Does anyone know of an airplane manufacturer that specifies engine or
wing anti ice systems need to be activated a set amount of time
(minutes) prior to entering icing conditions? The ones I've seen only
say "prior to entering...", but no requirement given to have it on for
a set time prior in order to heat up the surfaces.

Do far 25 rules testing provide any insights?

Stan

[Sam Spade]

wrote:
> Does anyone know of an airplane manufacturer that specifies engine or
> wing anti ice systems need to be activated a set amount of time
> (minutes) prior to entering icing conditions? The ones I've seen only
> say "prior to entering...", but no requirement given to have it on for
> a set time prior in order to heat up the surfaces.
>
> Do far 25 rules testing provide any insights?
>
> Stan

Any heavy iron I flew required that engine anti-ice be on within a range
of temperatures and where there was visible moisture (any cloud is
visible moisture). This policy (invoked by the aircraft manufacturers)
had nothing to do with whether you observed icing.

Wing deice is an entirely different issue. It is "deice." Engine heat
is "anti-ice."

[[email protected]]

This is what I've always heard too. Just that some people say putting
a-ice on "just prior" to entering icing conditions is NOT good enough,
as surfaces will not be fully heated by the time icing conditions are
encountered. I can't argue with the airmanship side of that, and I'm
not. But I am inquiring if any manufacturer has specified "2 minutes
prior" or something like that.

Similarly, does far25 icing tests allow time for systems to heat up,
or were they done by turning on a ice systems "just prior" to entry of
icing coditions? Thanks Sam. Anyone else with insights?

On Sun, 30 Nov 2008 06:44:20 -0800, Sam Spade >
wrote:

wrote:
>> Does anyone know of an airplane manufacturer that specifies engine or
>> wing anti ice systems need to be activated a set amount of time
>> (minutes) prior to entering icing conditions? The ones I've seen only
>> say "prior to entering...", but no requirement given to have it on for
>> a set time prior in order to heat up the surfaces.
>>
>> Do far 25 rules testing provide any insights?
>>
>> Stan
>
>Any heavy iron I flew required that engine anti-ice be on within a range
>of temperatures and where there was visible moisture (any cloud is
>visible moisture). This policy (invoked by the aircraft manufacturers)
>had nothing to do with whether you observed icing.
>
>Wing deice is an entirely different issue. It is "deice." Engine heat
>is "anti-ice."

[Sam Spade]

It's not airmanship. It is required of anyone who operates Part 25
turbine aircraft. I presume it is in Part 25 somewhere. I'll leave
that for you to research. ;-)

wrote:
> This is what I've always heard too. Just that some people say putting
> a-ice on "just prior" to entering icing conditions is NOT good enough,
> as surfaces will not be fully heated by the time icing conditions are
> encountered. I can't argue with the airmanship side of that, and I'm
> not. But I am inquiring if any manufacturer has specified "2 minutes
> prior" or something like that.
>
> Similarly, does far25 icing tests allow time for systems to heat up,
> or were they done by turning on a ice systems "just prior" to entry of
> icing coditions? Thanks Sam. Anyone else with insights?
>
> On Sun, 30 Nov 2008 06:44:20 -0800, Sam Spade >
> wrote:
>
>
wrote:
>>
>>>Does anyone know of an airplane manufacturer that specifies engine or
>>>wing anti ice systems need to be activated a set amount of time
>>>(minutes) prior to entering icing conditions? The ones I've seen only
>>>say "prior to entering...", but no requirement given to have it on for
>>>a set time prior in order to heat up the surfaces.
>>>
>>>Do far 25 rules testing provide any insights?
>>>
>>>Stan
>>
>>Any heavy iron I flew required that engine anti-ice be on within a range
>>of temperatures and where there was visible moisture (any cloud is
>>visible moisture). This policy (invoked by the aircraft manufacturers)
>>had nothing to do with whether you observed icing.
>>
>>Wing deice is an entirely different issue. It is "deice." Engine heat
>>is "anti-ice."
>
>

[[email protected]]

Sam, required of anyone who operates Part 25....? thats exactly what
I'm looking for. I've not come across where it is required to be on a
set amount of time before entry.

Realize this refers to a set amount of time prior to entry in icing
conditions.

Dassault falcon series, and the lear series for Bombardier that I've
seen in their AFM's just say "prior", with no specific time
stipulated. If you've some other info I'd like to see it.

On Tue, 02 Dec 2008 06:23:41 -0800, Sam Spade >
wrote:

>It's not airmanship. It is required of anyone who operates Part 25
>turbine aircraft. I presume it is in Part 25 somewhere. I'll leave
>that for you to research. ;-)
>
wrote:
>> This is what I've always heard too. Just that some people say putting
>> a-ice on "just prior" to entering icing conditions is NOT good enough,
>> as surfaces will not be fully heated by the time icing conditions are
>> encountered. I can't argue with the airmanship side of that, and I'm
>> not. But I am inquiring if any manufacturer has specified "2 minutes
>> prior" or something like that.
>>
>> Similarly, does far25 icing tests allow time for systems to heat up,
>> or were they done by turning on a ice systems "just prior" to entry of
>> icing coditions? Thanks Sam. Anyone else with insights?
>>
>

[Sam Spade]

Not about time, it's about conditions; i.e., engine anti ice is to be on
whenever visible moisture is present and the TAT is between +5 and -15,
or variations on that theme. Visible moisture is often clouds without
any apparent ice.

wrote:


> Sam, required of anyone who operates Part 25....? thats exactly what
> I'm looking for. I've not come across where it is required to be on a
> set amount of time before entry.
>
> Realize this refers to a set amount of time prior to entry in icing
> conditions.
>
> Dassault falcon series, and the lear series for Bombardier that I've
> seen in their AFM's just say "prior", with no specific time
> stipulated. If you've some other info I'd like to see it.
>
> On Tue, 02 Dec 2008 06:23:41 -0800, Sam Spade >
> wrote:
>
>
>>It's not airmanship. It is required of anyone who operates Part 25
>>turbine aircraft. I presume it is in Part 25 somewhere. I'll leave
>>that for you to research. ;-)
>>
wrote:
>>
>>>This is what I've always heard too. Just that some people say putting
>>>a-ice on "just prior" to entering icing conditions is NOT good enough,
>>>as surfaces will not be fully heated by the time icing conditions are
>>>encountered. I can't argue with the airmanship side of that, and I'm
>>>not. But I am inquiring if any manufacturer has specified "2 minutes
>>>prior" or something like that.
>>>
>>>Similarly, does far25 icing tests allow time for systems to heat up,
>>>or were they done by turning on a ice systems "just prior" to entry of
>>>icing coditions? Thanks Sam. Anyone else with insights?
>>>
>>

[Sam Spade]

Peter wrote:

wrote:
>>>
>>>>Does anyone know of an airplane manufacturer that specifies engine or
>>>>wing anti ice systems need to be activated a set amount of time
>>>>(minutes) prior to entering icing conditions? The ones I've seen only
>>>>say "prior to entering...", but no requirement given to have it on for
>>>>a set time prior in order to heat up the surfaces.
>>>>
>>>>Do far 25 rules testing provide any insights?
>
>
> With GA TKS systems, there is a low setting and a max setting. The
> advice is to use the low setting prior to entry into IMC, and use the
> high setting if icing is encountered - IIRC.
>
> I fly with a prop-only TKS systems and I always use the high setting
> only; 1 minute or so prior to entering freezing IMC.
>
> Airliners are different - they generally use hot bleed air and can run
> it indefinitely, power requirements (e.g. takeoff power) aside.
> Whereas TKS will run out.
>
> x----------x
Wing heat is de-ice. Engine heat is anti-ice.

Most airliners cannot use wing de-ice until after takeoff and at not
less than 400 feet; sometimes higher. The bleed air required for wing
de-ice takes so much power that it invalidates the takeoff flight path
performance.

[Andy[_1_]]

On Dec 3, 11:13*am, Sam Spade > wrote:

> Most airliners cannot use wing de-ice until after takeoff and at not
> less than 400 feet; sometimes higher. *The bleed air required for wing
> de-ice takes so much power that it invalidates the takeoff flight path
> performance.

MD-11 must be more sophisticated than "most airliners". If icing
conditions are expected on takeoff the wing and tail anti ice are
selected ON after engine start. The valves open when the aircraft
transitions from ground to in-air. Wing and tail anti ice cannot be
used on ground as the slats/leading edges will overheat.

In flight, the CFM requires wing and tail anti ice to be ON if icing
detection system indicates icing is present, or if icing is expected.
There is no specification of how soon before entering icing conditions
the systems should be selected ON.

Andy

[Scott Skylane]

Andy wrote:
> On Dec 3, 11:13 am, Sam Spade > wrote:
>
>
>>Most airliners cannot use wing de-ice until after takeoff and at not
>>less than 400 feet; sometimes higher. The bleed air required for wing
>>de-ice takes so much power that it invalidates the takeoff flight path
>>performance.
>
>
> MD-11 must be more sophisticated than "most airliners". If icing
> conditions are expected on takeoff the wing and tail anti ice are
> selected ON after engine start. The valves open when the aircraft
> transitions from ground to in-air. Wing and tail anti ice cannot be
> used on ground as the slats/leading edges will overheat.
>
> In flight, the CFM requires wing and tail anti ice to be ON if icing
> detection system indicates icing is present, or if icing is expected.
> There is no specification of how soon before entering icing conditions
> the systems should be selected ON.
>
> Andy

On the B-727, wing anti-ice cannot operate on the ground, but will open
up once airborne, like the MD-11. On the B-737-200, you *can* operate
the wing anti-ice on the ground, but it automatically snaps off when
takeoff power is applied, and must manually be switched back on once
airborne.

On the DC-6/7, fuel fired heaters blow hot air throughout the leading
edges, and of course there is no performance decrement. The heater
units are of the exact same type that supplies heated air to the cabin,
and circulates heated air in between the windshield panes.

Happy Flying!
Scott Skylane