View Full Version : B737 NG Wing Icing
Trash Hauler
8th Sep 2003, 19:11
Help please from B737 NG operators:
I have noticed that a light area of ice (frost really) forms on top of the wing in the inboard aft section after the aircraft has landed. I assume (now that can be dangerous) that it is the cold fuel condensing and freezing the moisture in the air that is in contact with wing surface. I have noticed this on the underside of the wing on other aircraft types but never on the upper surface.
My question: Does this icing on the upper surface have to be removed prior to flight and if so what are the approved methods?
I have noticed this on occasion here in Australia however I am not aware of de-icing facilities (such as those in the northern hemisphere) at the major airports. Does it present any operational restrictions to NG operators in Oz.
Trash Hauler
Wizofoz
8th Sep 2003, 21:58
Hi TH!
Yes, it has to be removed, ice is ice.
You are correct that it is caused by cold fuel in the tanks, which are a "Wet Wing" in the NG.
One trick:- transfer fuel from the wings to the centre using the manual de-fueling manifold, then fill the wings fron the bowser. The warmer fuel will raise the tank temperature and melt the ice.
Hope this helps:ok: :ok: :ok:
Onan the Clumsy
8th Sep 2003, 23:45
Not that you'd want to, but could you polish it instead?
avioniker
9th Sep 2003, 00:18
No no NO no , not even a little
Ice is ice
Waggon rut
9th Sep 2003, 00:47
Have not seen ice on the top part of the wing ice yet, bottom upto 3mm is ok to fly with.
Cakov
11th Sep 2003, 05:37
As long as you land with less than about 3000kg in each wing tank (they hold about 3900kg when full), the ice will melt when the tanks are filled up with "warm" fuel from the bowser.
lomapaseo
11th Sep 2003, 05:54
Wing ice formation is a function of distance from top of fuel to underside of wing skin or a combination of thermal conductivity (wing skin) as well as thermal convection (air above fuel). Factor in the temperature of the fuel (cold soaked) and if water vapor is present in still air.
And yes the outside air temperature needs to be considered relative to themal conductivity of the wing skin.
Upper wing ice may be likely in temperatures as high as 45 degrees F if full tanks are present.
Wing ice has been a surprise player in engine damage (DC9 series 30-80), but unseen ice from overnight precip (clear ice) has been the cause of more ice related accidents
Trash Hauler
11th Sep 2003, 19:04
Thanks for the responses.
I wondered how the DJ aircraft were dealing with it on the ramp at Melbourne. Don't know if they are carrying more fuel but they seemed to have more of the frost. Never seen a 'de-ice' action so I guess they must be doing the fuel transfer and refuel.
Any QF drivers out there experienced this event?
Cheers
Trash Hauler
tykon
12th Sep 2003, 22:43
hi, I have done several de-ices on VB.
The best test for ice is to, when you walk up the front stairs, rub the fuse on the aft left side of the door. If no ice, no de-ice procedure needed, if ice, then it is needed.
Also, I have found ice will start on the ib trailing edge first, so, if over about 5 foot tall, you will beable to reach theupper side and feel if ice.
Done bother about all the jargon and rubbish with temps etc. If there is ice on the wing, you will see it. Underside is allowed up to 1/8 inch, which, believe me, you will notice. Basically nothing on the top at all.
Takes about 20 mins to de-ice, so not hard to do. If anyone is in doubt, just do it. simple.
See ya
About wing icing on top of the wings of a Boeing 737 NG I have to mention at least the following:
"...Thin hoarfrost is acceptable on the upper surface of the fusalage provided all vents and ports are clear. Thin hoarfrost is a uniform white deposit of fine crystalline texture, which usually occurs on exposed surfaces on a cold and cloudless night, and which is thin enough to distinguish surface features underneath, such as paint lines, markings or lettering..."
The text above is an exact copy taken from the supplementary procedures in the operations manual from Boeing. I would say in some cases it is possible to have a little bit of ice on top of the wings. I agree with the comments made earlier in this topic, I just wanted to let everybody know that there might be an exception to the case.
Always fly safe!
Cakov
15th Sep 2003, 21:08
Thin hoarfrost is acceptable on the fuselage, but NOT the wings.
I have to stand corrected.
wellthis
21st Sep 2003, 10:16
As mentioned above, thin frost on the fuselage and under the wing due to coldsoaking is acceptable, but haven't heard of any country/operator that allows it on the top.
If you guys don't need deicing facilities down there, then you're lucky!
However, if it takes too long to get things organized, I have seen frost being swept-off to expedite things, it actually comes off rather easy. Someday this might help.
exeng
30th Sep 2003, 02:08
Arrived after a 5 hour sector to find ice on the upper wing surfaces. The ice extended from approx 2 ft inboard of the engine pylon to about 6 ft outboard. A very small amount was evident at the wing tip also.
We refuelled uplifting 1800 Kg's to each wing tank. The ice remained even after refuelling. OAT was 24 C. with fuel tank temp 16 C after refuelling. Cruise TAT for the flight was @-35 C. Virtually no visible moisture for the entire flight.
We attempted to 'wash off' the ice with water from the 'potable water' bowser. (De-icing not available) This made matters worse with some of the water freezing again. Eventually we managed to get hold of an airport fire truck and applied large amounts of warmish water which did the trick.
I have to confess to being very surprised that refuelling did not clear the original ice.
Regards
Exeng
RatherBeFlying
30th Sep 2003, 03:09
Some a/c, eg. A310, are approved for takeoff with hoarfrost on upper wing surface over fuel tanks and perform just fine. The operative principle is that a small percentage of non-critical wing area is involved. Contamination of leading edge area is far more critical.
Your a/c may or may not be so approved -- check the manual.
Some countries do not allow takeoffs with any ice at all.
Sweeping may not completely remove hoarfrost. If deice fluid is not available (automotive windshield washer and engine coolant can do as they generally contain ethylene glycol) and hoarfrost covers a substantial area, warm water and careful inspection are called for.