CA1278979C - Aircraft de-icing system - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

An aircraft de-icing system is disclosed which comprises an aircraft-washing hardstanding onto which an aircraft can be moved, means for spraying de-icing fluid onto the aircraft, and means for collecting and carrying away the fluid. In order to enable the fluid to be removed from the hardstanding quickly and reliably, the hardstanding is constructed so as to comprise a substantially planar surface layer of so-called drainage asphalt, and an impervious layer which is located beneath the planar surface layer and which slopes steeply down towards drainage pipes, so as to collect and carry away the de-icing fluid passing down through the surface layer.
The system also preferably includes a pump arranged to draw air down through the surface layer so as to entrain therewith any water vapour formed and thus prevent the formation of vapour clouds liable to rise from the hardstanding.

Description

~89~

The present invention relates to an aircra~t de-icing system of the kind which comprises an aircraft-washing hardstanding which presents an aircraft carriageway; means for spraying the aircraft with de-icing fluids and drainage means for collecting and carrying away the de-icing fluid.
In de-icing systems of this kind, for example the system illustrated and described in Swedish Patent Specification 7713619-0, the hardstanding exhibiting the carriage way must be constructed 50 as to he able to withstand the heavy load exerted by an aircraft, and 50 as to enable an aircraft to be moved safely into position in the ahsence of any disturbing irregularities which might cause the wingtips of the aircraft to swing and be damaged by contact with, for example, washing or spraying devi~e~
and the like located in the vicinity of the various aircraft parts.
At the same time, the arran~ements used to collect and carry away the large quantities of de-icing fluid which run down from the aircraft onto the hardstanding area must be highly effective, without presenting too much of an obstacle to smooth forward movement of the aircraft. In addition, it has been fo~nd that, in the majority of weather conditions, heavy mists are formed if the used de-icing fluid is not removed and dispensed with quickly enough, such mists ~eing also troublesome to those parts of the airfield located in the vicinity of the de-icing station.
An ohject of the present invention is to provide a system in which the aforesaid disadvantages are avoided substantially completely, in a simple and inexpensive fashion.
Accordingly, the invention provides an aircraft de-icing system comprising an aircraft-washing ~5 hardstanding incorporating a carriageway for an aircraft, a stationary or movable portal structure e~tending across the hardstanding and provided with pipes and nozzles so po~itioned that an aircraft on the carriageway and said B ~v~

- . ~

.
. :
~ .

~'789~9 portal structure are mutually movable with the nozzles located at a predetermined distance from the various parts of the aircraft, and means, such as pumps, tanks, filters and valves for pumping de-icing fluid under high pressure 5 to said pipes and nozzles, the hardstanding comprising a substantially planar surface layer structured from a liquid-permeable road-surfacing material, and under said surface layer an impervious layer which slopes towards drainage pipes connected to a pump for collecting and 10 carrying away the de-icing fluid and removing water vapour from the liquid permeable surface layer by suction.
With a hardstanding constructed in this manner, the de-icing fluid running down onto the surface layer will pass directly through said surface layer, which can 15 consequently be of planar configuration, since the arrangements and devices for collecting and carrying away the de-icing fluid are located beneath the surface layer.
A hardstanding of this construction also affords the important advantage of enabling the drainage pipes to 20 be connected to a pump arranged to remove water vapour from the liquid-permeable surface layer by suction. In this way water vapour is prevented, to a large extent, from rising up from the aircraft-washing hardstanding and sweeping into the aircraft in the form of a vapour cloud, which is o~
25 considerable benefit with respect to process performance and with respect to the general visibility in busy and crowded airfields. The surface layer also serves as a coarse filter, in which leaves, twigs etc. can be caught.
The suction pump is therefore suitably adapted for 30 switching to a mode in which air is temporarily blown through the drainage pipes and up through the outer surface, so that any foreign objects present can be blown free from the channels and passageways of the surface layer. Preferably, cold ambient air, or optionally chilled 35 air is blown through said passageways for a suitable length of time immediately prior to commencing a de-icing process, which normally takes about three minutes to complete. This affords the advantage of cooling the 2a ~urfacç layer and the drainage and discharge pip~s to an extent sufficient to cool the water vapour sucked down through the surfaGe layer throughout the whole of the de-icing process, 50 that the water contained in the water vapour condenses prior to the water vapour reaching the pump in the machine room.

~' -`'' ~
: ' , . , ; ' ' , -.' .

~89~3 Embodiments of the invention will now be described in more detail with reference to the accompanyin~ drawin~, which is a perspective view, partly in section, of an embodiment of a de-icing system according to the invention.
The drawing illustrates an elongated rectangular aircraft-washing hardstanding 1 which is situated on an airfield, suitably with direct access to the aircraft approach path leading from the airfield buildings to the aircraft runways~ The hardstanding 1, has a breadth which is slightly larger than the wing span of the largest aircraft which can be expected for treatment, and extending across the hardstanding is a portal 2 provided with pipes and nozzles 3 so positioned that an aircraft ~
rolling onto the hardstanding 1 is able to pass through the portal with the nozzles located at a pre-determined distance from the various parts of the aircraft, particularly from the upper and lower surfaces of the wings of the aircraft. Located on one side of the portal 2 is a supervising cabin 5. Located adjacent the cabin 5 is a partially submerged machine room 6, to which the pipes 3 provided with the aforesaid spray nozzles extend.
The hardstanding 1 is constructed of three mutually different layers, namely a bottom supporting layer 10, an impervious layer 11 which is located above the support layer 10 and comprises a liquid-impermeable material, such as concrete, and which slopes steeply from both sides of the center line of the hardstanding 1, and finally a top surface layer 12 which comprises a liquid-permeable ~aterial, such as a road surfacing material, for example drainage asphalt, and which has a sub~tantially planar top surface.
The liquid-permeable material is suitably a hot-mixed (150-170C) asphalt concrete having cavities of 15-20~ and about 60% ballast material of largest ballast fraction, and a fibre addition which increases the compression strength of the material and its length of useful life.

..... , . ; ~. . . .

~7~3g~

Drainage pipes 15 are embedded in the longitudinal edges of the impervious layer 11 around the hardstanding 1, so that all liquid penetrating down through the surface ayer 12 and running over the impervious layer is collected in the drainage pipes 15.
The drainage pipes 15 are connected to the machine room 6 by means of discharge pipes 16. The machine room 6 houses an arrangement of pumps, tanks, filters, valves etc. for pumping under high pressure a water-glycol-mixture of varying concentration to the pipes 3 and the nozzles as the aircraft is 510wly moved through the portal 2. All surfaces of the aircraft are contacted by the liquid jets in accordance with a pre-determined program, whereupon ice and snow are loosened and washed from the aircraft and fall onto the hardstanding 1 together with the de-icing fluid, after which the fluid and the molten snow and ice quickly pass through the surface layer 12 onto the impervious layer 11 and from there through the drainage pipes 15 and the discharge pipes 16 to the machine room 6, where the fluid is reconditioned and strengthened to the desired concentration for renewed pumping to the pipes 3 and nozzles of the portal 2.
The machine room 6 also houses a large-capacity vacuum pump ~ which is connected to the discharge pipes 16, this vacuum pump being actuated to draw a flow of air downwardly through the surface liayer 12. Tho~e clouds of water vapour which would otherwise rise up from the hardstanding 1 and which derive from the relatively warm de-icing fluid in cold weather will thereby be drawn through the drainage and discharge pipes 15, 16 instead, which is an important feature of the invention.
The portal 2 need not be an immovable structure, but may be arranged for movement in the longitudinal direction of the hardstanding 1, in which case the aircraft can be allowed to remain stationary during the de-icing process.

, , '

Claims (3)

1. An aircraft de-icing system comprising an aircraft-washing hardstanding incorporating a carriageway for an aircraft, a stationary or movable portal structure extending across the hardstanding and provided with pipes and nozzles so positioned that an aircraft on the carriageway and said portal structure are mutually movable with the nozzles located at a predetermined distance from the various parts of the aircraft, and means for pumping de-icing fluid under high pressure to said pipes and nozzles, the hardstanding comprising a substantially planar surface layer structured from a liquid-permeable road-surfacing material, and under said surface layer an impervious layer which slopes towards drainage pipes connected to a pump for collecting and carrying away the de-icing fluid and removing water vapour from the liquid permeable surface layer by suction.

2. A de-icing system according to claim 1, wherein the road-surfacing material is so-called drainage asphalt comprising a hot-mixed (150°-170°C) asphalt concrete having cavities of 15-20% and about 60% ballast material of largest ballast fraction and a fiber addition.

3. A de-icing system according to claim 2, wherein the pump can be switched to a mode in which it temporarily blows cold ambient air through the drainage pipes and up through the surface layer.