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Use of Anti Icing
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 |
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Use of Anti Icing
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#3
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Use of Anti Icing
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." |
#5
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Use of Anti Icing
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? |
#6
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Use of Anti Icing
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? |
#7
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Use of Anti Icing
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. |
#8
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Use of Anti Icing
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 |
#9
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Use of Anti Icing
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 |
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