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rubik101
28th Feb 2005, 15:54
I have recently seen several B737s of a certain airline taxiing out to the holding point with steaming leading edges after having been de-iced. As far as I know Boeing recommend that Wing Anti ice should NOT be used after de-icing to preserve the fluid on the leading edge. Any comments?

catchup
28th Feb 2005, 16:29
Does it work on ground?

regards

rubik101
28th Feb 2005, 18:43
Indeed it does work on the ground. It does however, switch off when the Thrust levers are advanced beyond about 2/3 open. (B737)

Wizofoz
28th Feb 2005, 20:37
Procedure is to have wing anti-ice off after deicing with type II 0r IV fluid, and to have it on if another type is used.

Flight Detent
1st Mar 2005, 01:16
Rubik,

For the NG, you're quite right too!

Just wanted to add that the wing de-ice bleed is also controlled by the thermal switches on the ground, ie, the bleed is monitored on/off as they heat up/cool.

Then the thrust lever position signals bleed shut-off during the t/o roll, and the control switch clicks off at rotation.

I believe!

Cheers, FD

Touch'n'oops
1st Mar 2005, 02:20
Very good Flight Detent!!!

You have earned extra pudding!!!:ok:

Old Smokey
1st Mar 2005, 05:32
Steaming aircraft.....

Part of the De-Iceing process (as distinct from the Anti-Iceing process) is the application of very hot fluid to the airframe. This will probably account for the observed 'steaming'.

Only a few days ago in Seoul, whilst awaiting our own de-iceing, observed many aircraft leaving the de-iceing pads with steaming fuselages, and fuselages definately don't have aircraft Anti-Ice.

Regards,

Old Smokey

rubik101
1st Mar 2005, 08:08
I accept that the hot fluid will steam for a time. This steaming was ten to fifteen minutes after application. It was observed as we taxiied out right up to the holding point and very definitely coming from the leading edges only. The thing that surprised me was that it carried on for so long. We were queing for take off for up to 30 mins and still it steamed!

ifleeplanes
1st Mar 2005, 08:29
Our SOP is to put Wing and Engine icing on if you have deiced and you are in icing conditions on the taxi out. There are various disgussions with regard to type IV and indeed type II fluid and rehydration using this procedure. However your a brave man to ignore the SOP.

Wizofoz
1st Mar 2005, 09:59
ifleeplanes,

Wise words regarding SOPs, but what I outlined is the SOP for my company, and the three I worked for previously. Could you give some indication who you fly for, as I,m pretty sure your procedures are against Boeing recommendations (not saying you neccessarily fly a Boeing, but I'd be suprised if Airbus was any different0

CaptainSandL
1st Mar 2005, 11:11
The current 737 (all series) Vol 1 SP.16.5 states:-

“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, unless the airplane is protected by the application of Type II or Type IV fluid in compliance with an approved ground de–icing program.

WARNING: Ground use of the wing anti–ice system is intended to complement, and not replace, ground de–icing/anti–icing and inspection procedures. Close inspection is still required to ensure that no frost, snow or ice is adhering to the wing, leading edge devices, stabilizer, control surfaces, or other critical airplane components at takeoff.”

I don’t think there is any grey area here. If your company has an SOP which is contrary to the above perhaps you should mention it to your fleet manager.

As to the background for the rule and the anomaly for non Type II or IV fluids, Boeing Aero magazine, issue No. 08, October 1999, had an article under 'Safety' on page 3 entitled “New, DEICING/ANTI-ICING FLUIDS”. In it, it discusses the development of new fluids, particularly Type IV and new problems to be addressed with longer hold-over times. One of the problems is the fact that the fluid can partially dry out before its hold over time has expired. Thus when it is supposed to shear off and leave a clean wing prior to lift off, in actual fact a thin film can be left on the surface of the wing which may affect the aerodynamic characteristics of the wing. Two of the situations where this was described were exposure to cold dry air and ground operation of heated wing leading edge systems.

In addition to the practical risks (above) there is an ongoing disagreement about standards which even after 6 years has still to be resolved:
“When AMS 1428 was issued, it was consistent with the ISO and AEA fluid standards. When AMS 1428 was revised (Oct 1998) to include standards for Type IV fluids, the SAE G-12 committee worked closely with the AEA ground de-icing working group to develop consistent standards. These standards could be used to revise the ISO standard and provide all operators with consistent standards for Types II, III, and IV fluids. However, the ISO standard has not yet been revised. Because of this situation and frequent changes to the SAE standard, Boeing has revised its AMMs and service letters to refer only to the latest revision of the SAE standard."

The bottom line is that you should not use wing A/I if you have been treated with Type II or IV fluids as per the current Vol 1. If you do, your hold over times will be reduced and you may also degrade the wing aerodynamic characteristics. If your airline has an SOP which is contrary to this, you should bring it to their attention.

S & L (www.b737.org.uk/iceandrain.htm)

(Edited for layout)

Popolama
1st Mar 2005, 20:23
some are saying that boeing recommands to use wing anti ice only with flaps up...is that true ? nothing on FCOM 1

rubik101
3rd Mar 2005, 08:44
It makes no difference to the function of the wing anti ice whatever the flap position, hence no mention of it.
I made the query simply because it is my understanding, as indicated above, that it should NOT be used on the ground after de-icing. If the company has written something else then I wonder if they have consulted Boeing for a a No Technical Objection status on that SOP.

Phil Squares
3rd Mar 2005, 10:02
I can't comment on the 73, but on the 747/744 with the flap handle out of the up position, there is no wing heat. So you can select wing heat on the ground, but it's not going to do anything.

Going back into the dark recesses of my mind, I seem to remember the 727 and 757 being the same way. Flaps handle out of the up position = no wing heat.

Wizofoz
3rd Mar 2005, 17:45
There is a Boeing recommendation to leave flap selection until just before line-up if there is slush, standing water etc. and icing conditions, so as to avoid ice accretion during taxi.

Flight Detent
4th Mar 2005, 01:30
Hi Phil,

I don't remember that on the B747 Classics I used to operate.

I seem to remember that the rule was that the LE de-icing was not effective with the LEs not fully retracted, but one could still turn the system on anytime inflight, even with flaps extended!

Please refresh my memory!

FD :rolleyes:

rubik101
4th Mar 2005, 16:29
I posed the question simply to point out that maybe, perhaps, just possibly, said airline is using the wrong procedure. Can anyone explain why we are reading the same Boeing SOPs and arriving at different Company SOPs? One of us is mistaken.

Noak
4th Mar 2005, 18:12
The current 737 (all series) Vol 1 SP.16.5 states:
-“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, unless the airplane is protected by the application of Type II or Type IV fluid in compliance with an approved ground de–icing program.

WARNING: Ground use of the wing anti–ice system is intended to complement, and not replace, ground de–icing/anti–icing and inspection procedures. Close inspection is still required to ensure that no frost, snow or ice is adhering to the wing, leading edge devices, stabilizer, control surfaces, or other critical airplane components at takeoff.”

I don’t think there is any grey area here. If your company has an SOP which is contrary to the above perhaps you should mention it to your fleet manager.

In our B737NG FCOM Vol 1 SP.16.5 it is stated:

"Wing anti-ice operation on ground before takeoff is NOT X (X=our company) approved procedure.

WARNING: Use of wing anti-ice system during ground operation before takeoff is not approved.
Close inspection is required to ensure that no frost, snow or ice is adhering to the wing, leading edge devices, stabilizer, control surfaces, or other critical airplane components at takeoff.
The airplane shall be treated in accordance with the de-/anti-icing procedure."

Popolama
4th Mar 2005, 21:56
can t find something about use of WAI only with flaps up.comments about engine out climb penalty in case of WAI use on CLB ? by the time we raise the flaps, WAI can then be used as deicer

just found these limitations about B752.

On takeoff and landing, Wing Anti-ice should be OFF below 500 feet AAL to meet performance criteria. If an engine has failed, it must not be switched on until Flaps Up. These requirements are in order to achieve certificated climb gradients. For wing Anti-ice with inoperative engine only one Pack may be used.

Jambo Buana
5th Mar 2005, 16:19
As you may or may not know, the FCOM 1 manual can be edited by a company to suit its SOP's. This is the case with the 'certain' company that puts its WAI ON during ground operations in icing conditions. This was a decision taken with Boeing Training Standards, who have No Technical Objection to the procedure, and are happy with either way provided that NO ICE IS PRESENT ON THE WING for takeoff. Certainly this particular airlines LE will be ice free approaching the holdover time, won't it?

LEM
6th Mar 2005, 07:44
I'm surprised nobody mentioned the two different systems installed on 737's (classics).

Are we the only ones to have the two models?

Our company has acquired a bunch of airplanes from everywhere in the last years (from Holland, Spain, British etc...) and we operate with several different layouts (some even have dual steering, or the audio control box external to the pilot seat, close to the mask - which everybody hates, including me!).

Talking about wing anti-ice, we have two models:

1) ON - OFF. Two position switch, which can be operated on the ground, and closes with TO thrust, and trips at liftoff.

With this kind of system installed, the procedure quoted by CaptSandl is the correct one.

2) GND TEST - OFF - ON. Three position switch, which works exactly the opposite way!

You cannot operate wing anti-ice on the ground, unless you hold the spring loaded switch to GND TEST momentarily.
This would only be to make a functional test.

But you can arm wing anti-ice by placing the switch to ON.

At liftoff, the valves will open.

Funny, isnt'it?
Now, you see that in the same company we operate with two totally different procedures...

And the question is: if two opposite procedures are good, according to Boeing, isn't it all this sort of BS???? :mad:

And the confusion amongst our crews seems to prove this... as I'm always amazed I seem to be one of the very few guys who turn the wing anti-ice ON on the ground, with the first model described.

LEM

ivor tug
6th Mar 2005, 10:59
Hi LEM do you also take a 3500 kg climb penalty for the old system, ie the one activated after take off. Also has anyone considered a bleeds off take off. WAI only available after you've reconfigured the air system.

LEM
6th Mar 2005, 17:46
Hi ivor tug, yes of course you have to apply the penalty if at any point in the take off profile you plan to use wing and/or engine anti-ice.

Btw, I don't think anybody will ever arm wing anti-ice before takeoff, as we know the 737 doesn't have any problem, except under extreme icing conditions, maybe.