Wing anti-ice on the ground
Guest
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One thing no one has mentioned yet on this topic is the term "blow back" where leading edge heat simply causes moisture to run back over the wing and freeze further along the chord. This I believe is why on most? types wing de-icing is used rather than anti-icing.
This has certainly been the case on both types I have flown.
This has certainly been the case on both types I have flown.
Guest
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Track,
Just got a reply from our FLT TECH department.
According to them Boeing states in their manual (quote):'WAI may be used as a de-icer or anti-icer in flight only.'
This applies for 733, 734 and 738, 739
Wonder what the guys from Legro say?
[This message has been edited by static (edited 02 January 2001).]
Just got a reply from our FLT TECH department.
According to them Boeing states in their manual (quote):'WAI may be used as a de-icer or anti-icer in flight only.'
This applies for 733, 734 and 738, 739
Wonder what the guys from Legro say?
[This message has been edited by static (edited 02 January 2001).]
Guest
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And just for the sake of "correctness" the A320 family does allow wing anti ice to be selected on the ground for test purpose only and to correct m&v if I may it is for 10 seconds only. There is no limit to the amount of tests..... 
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Gravity always wins....
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Gravity always wins....
Guest
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On the Boeing 757-200: (From Aircraft Manual)
WING ANTI-ICE SYSTEM
"The wing anti-ice system provides bleed air to three midwing leading edge slats on each wing. Wing anti-ice can be operated in flight ONLY. It is inhibited on the ground."
It may vary, but I would have thought all Boeings are the same?
Best wishes
Eff Oh.
WING ANTI-ICE SYSTEM
"The wing anti-ice system provides bleed air to three midwing leading edge slats on each wing. Wing anti-ice can be operated in flight ONLY. It is inhibited on the ground."
It may vary, but I would have thought all Boeings are the same?
Best wishes
Eff Oh.
Guest
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Air ground sensing is there to prevent wing TAI operation on the ground,& to prevent wing structure overheat & possible failure due to lack of airflow!!! Also on B757 you can get up to 30* temp drop at the eng. inlet requiring 50% N1 every 15 min. to shed ice from the LP stators, so obviously the engine TAI is not doing the full job!!!!!!!!!!!
Guest
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Static,
The same B-737 manual states in the Adverse Weather Section, under Wing Anti-Ice Operation on the Ground,
"Wing anti-ice must be ON during all ground operations between engine start and takeoff, when icing conditions exist or are anticipated."
Warning: Ground use of the wing anti-ice is intended to complement, and not replace, ground de-icing/anti-icing and inspection procedures."
The same B-737 manual states in the Adverse Weather Section, under Wing Anti-Ice Operation on the Ground,
"Wing anti-ice must be ON during all ground operations between engine start and takeoff, when icing conditions exist or are anticipated."
Warning: Ground use of the wing anti-ice is intended to complement, and not replace, ground de-icing/anti-icing and inspection procedures."
Guest
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Ron,
Thanks for the info. The thing is, my company doesn`t use the Boeing manuals off the shelve. They write their own manuals, based on the Boeing books, ofcourse, but with a lot of other things added. Now it seems they may have left something out (?).
Could you give me page numbers or other references out of the Boeing manuals? Another question: is that for Boeing 733 or 732? Or NG?
Thanks
Thanks for the info. The thing is, my company doesn`t use the Boeing manuals off the shelve. They write their own manuals, based on the Boeing books, ofcourse, but with a lot of other things added. Now it seems they may have left something out (?).
Could you give me page numbers or other references out of the Boeing manuals? Another question: is that for Boeing 733 or 732? Or NG?
Thanks
Guest
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Eff Oh
Not only are all Boeings not the same, but also not all 737-300’s are the same! See Statics reference to a ground test position on some -300’s. Although I suspect that the rest of the system is the same.
Re JD’s comment above, again I can only speak about the 737 classics, but the air-ground sensor will only bypass the duct temp and thrust setting logic when on the ground. It does not shut off hot air to the wing simply because you are on the ground. The wings are heated on the ground, although not to the same extent as in-flight. Why else would Boeing need to change the procedure for its use on the ground if the switch position did not matter?
S & L
Not only are all Boeings not the same, but also not all 737-300’s are the same! See Statics reference to a ground test position on some -300’s. Although I suspect that the rest of the system is the same.
Re JD’s comment above, again I can only speak about the 737 classics, but the air-ground sensor will only bypass the duct temp and thrust setting logic when on the ground. It does not shut off hot air to the wing simply because you are on the ground. The wings are heated on the ground, although not to the same extent as in-flight. Why else would Boeing need to change the procedure for its use on the ground if the switch position did not matter?
S & L
Guest
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Static,
My company's tech pilot referred to the same text as Ron quoted:
"Wing anti-ice must be ON during all ground operations between engine start and takeoff, when icing conditions exist or are anticipated."
BUT with the following added:
"If deicing fluids types II or IV are used WAI may be left off"
So for us the procedure is :
Icing conditions NOT deiced: WAI on
Icing conditions and deiced: WAI off
ref: Boeing 737-800 AOM Supplementary procedures, SP 16.5.
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Track
My company's tech pilot referred to the same text as Ron quoted:
"Wing anti-ice must be ON during all ground operations between engine start and takeoff, when icing conditions exist or are anticipated."
BUT with the following added:
"If deicing fluids types II or IV are used WAI may be left off"
So for us the procedure is :
Icing conditions NOT deiced: WAI on
Icing conditions and deiced: WAI off
ref: Boeing 737-800 AOM Supplementary procedures, SP 16.5.
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Track
Guest
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What I've missed in the discussion so far is a bit in line with F/E Hoppy's remark on blowback. Wing Anti Ice systems normally only heat up the Leading Edge of the wing.
During operation on the ground the ice collects on the entire top of the wing during precipitaion and all the cold parts (top and bottom) of the wing during frost conditions. As we all can see every now and then during flight ice starts to collect at the leading edge, possibly spreading a bit further aft but hardly ever more than about 10 percent of the cord. Wing Anti-Ice systems are designed to clear this "In-Flight" buildup of ice. They do keep the forward 10 percent of the wing clear of ice while operating on the ground but this is not nearly enough. Before T/O I'd like to have the entire wing or at least the top free of ice, leaving room for a light frost on the bottom.
A proper de-icing treatment clears the entire wing and protects it for the length of the holdover time. If I then heat up the leading edge the glycol evaporates and I lose this protection of the forward 10 percent and trade it for thermal Anti Icing.
Apart form company rules that seem to differ on the subject: What do I loose, what do I gain? Anyone?
Sq
During operation on the ground the ice collects on the entire top of the wing during precipitaion and all the cold parts (top and bottom) of the wing during frost conditions. As we all can see every now and then during flight ice starts to collect at the leading edge, possibly spreading a bit further aft but hardly ever more than about 10 percent of the cord. Wing Anti-Ice systems are designed to clear this "In-Flight" buildup of ice. They do keep the forward 10 percent of the wing clear of ice while operating on the ground but this is not nearly enough. Before T/O I'd like to have the entire wing or at least the top free of ice, leaving room for a light frost on the bottom.
A proper de-icing treatment clears the entire wing and protects it for the length of the holdover time. If I then heat up the leading edge the glycol evaporates and I lose this protection of the forward 10 percent and trade it for thermal Anti Icing.
Apart form company rules that seem to differ on the subject: What do I loose, what do I gain? Anyone?
Sq
Guest
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...please allow me to bring even more confusion to this very enlightening dicussion:
the FPPM (flight planning and performance manual) available from boeing itself for all B737 versions is calling to substract 1350 kgs (as far as I recall) from the FIELD LIMIT WHEIGHT, when using WING AND COWL ANTIICE !
Strange enough if u consider that the wing antiice valves close automatically with the application of TO thrust on all our 737,s(300,400,600,800). So it should never effect the field limit, should it ?
Obviously there there is more than one customer option flying along giving us these respectable headaces.
Whatsoever, Bombardier forbids the use of TWAI after deicing to prevent clogging (as u figured it, Sandy), and for the boeing case I am in TRACKS team, check your six !
the FPPM (flight planning and performance manual) available from boeing itself for all B737 versions is calling to substract 1350 kgs (as far as I recall) from the FIELD LIMIT WHEIGHT, when using WING AND COWL ANTIICE !
Strange enough if u consider that the wing antiice valves close automatically with the application of TO thrust on all our 737,s(300,400,600,800). So it should never effect the field limit, should it ?
Obviously there there is more than one customer option flying along giving us these respectable headaces.
Whatsoever, Bombardier forbids the use of TWAI after deicing to prevent clogging (as u figured it, Sandy), and for the boeing case I am in TRACKS team, check your six !
Guest
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We also correct for WAI and EAI for takeoff performance calculations:
250 kg for EAI, 1350 kg for WAI and EAI together.
The reason for the correction on WAI is not clear to me. Either Boeing thinks the trip off mechanism might fail or they think we are fast enough to switch the system back on again after liftoff but before 35 feet, since this is the end of the takeoff for performance calculations.
I'm gonna practice on the last possibility
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Track
[This message has been edited by Track (edited 08 January 2001).]
250 kg for EAI, 1350 kg for WAI and EAI together.
The reason for the correction on WAI is not clear to me. Either Boeing thinks the trip off mechanism might fail or they think we are fast enough to switch the system back on again after liftoff but before 35 feet, since this is the end of the takeoff for performance calculations.
I'm gonna practice on the last possibility
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Track
[This message has been edited by Track (edited 08 January 2001).]
Guest
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hehe, track, u name it.
I personally like the idea that boeing does'nt thrust it's own equipment and giving us data to cover it's s..t, but, by the way, where is our iknoweverythingaboutboeing officer on duty ?
and ,jessir, i'm shure it's not the landing field lenght.
...check your six !
I personally like the idea that boeing does'nt thrust it's own equipment and giving us data to cover it's s..t, but, by the way, where is our iknoweverythingaboutboeing officer on duty ?
and ,jessir, i'm shure it's not the landing field lenght.
...check your six !
Guest
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Pullupnow & Track,
There is no reference to a wing anti-ice correction in our FFPM and, on checking the 300 CAA AFM there is no correction for field (or any other) limits. Can you find a reference for it & post it up, if it does exist we should know.
S & L
There is no reference to a wing anti-ice correction in our FFPM and, on checking the 300 CAA AFM there is no correction for field (or any other) limits. Can you find a reference for it & post it up, if it does exist we should know.
S & L
