Ice detection method and apparatus for an aircraft

A method an apparatus for detecting icing on an aircraft particularly flight surfaces by using the electrical insulating properties of ice on a conductive wing surface utilizing a simple conductive current device engageable selectively on the suspect flight surfaces.

BACKGROUND OF THE INVENTION 
1. Technical Field 
This invention is directed to an aircraft icing detector which is critical 
in determining aircraft performance and safety. Ice accumulation on flight 
surfaces will often occur in conditions that would not seem likely. Modern 
aircraft design having more efficient wing characteristics make them more 
vulnerable to any ice accumulation that will decrease the lift efficiency 
and increase drag. If surface friction is increased by contamination and 
surface roughness which can be directly attributed to ice accumulation, 
increased drag will occur with flight performance and stabilization will 
be effected. Modern aircraft store fuel in the wings which will be chilled 
during flight thus creating lower flight surface temperatures which when 
combined with the ambient moisture content of the surrounding air can form 
ice even in non-freezing air conditions that would not normally be 
conducive to ice formation. 
Clear ice formations on flight surfaces is especially dangerous since it 
cannot readily be seen by visual inspection and requires careful hands on 
inspection by properly trained personnel. Ice detection on aircraft's 
critical upper wing surface areas are difficult to inspect due to the wing 
height and wing dimension. Normal inspection procedures on such aircraft 
require a step ladder be positioned adjacent the wing allowing the 
inspection personnel to physically climb high enough so that a wide 
section of the wing area can be inspected by hand. Engine blade icing is 
also of a critical concern when ice forms on the fan blade surfaces found 
in modern jet and turbo-prop aircraft. Engine damage is caused by ice 
injection during take-off when ice breaks away from flight surfaces in 
front of the engine and is ingested impinging against the fan blades 
causing damage which can effect flight performance and engine output. 
2. Objects and Advantages 
It is the object of this invention to provide for a simple self-contained 
ice detection device that can be readily used by flight and ground 
personnel to easily and quickly inspect critical wing surfaces for the 
presence of ice especially clear ice which is less readily detectable by 
visual inspection. 
An advantage of the invention is directed towards the absolute 
determination of ice presence by the relative conductivity of the wing 
surface allowing the flight and ground personnel to inspect the wing 
without physically touching it which heretofore is the most effective and 
most fail safe method of determining the accumulation of clear ice. 
Description of Prior Art: 
Prior art devices to help determine the presence of ice on flight surfaces 
before take-off have relied on both visual inspection and hands on 
inspection by flight and ground personnel, see for example U.S. Pat. Nos. 
5,313,202, 5,180,122, 4,398,412, 3,045,223 and 2,432,669. 
In U.S. Pat. No. 3,045,223 an ice detection device is disclosed that 
utilizes light transmission between a light source and detector to 
determine the presence of foreign material therebetween. 
U.S. Pat. No. 4,398,412 is directed to a device to determine frost depth 
and density by using a hand held visual gauge through which the frost can 
be cited and thus measured. 
U.S. Pat. No. 2,432,669 responds to the formation of ice by using the 
electrical capacitance principle in which one plate of the condenser is 
the pick-up dish mounted to an insulated plate on the wing. The other 
condenser plate is the wing itself thus measuring oscillating electrical 
fields between same as ice forms thereon. 
U.S. Pat. No. 5,180,122 on an apparatus for de-icing illustrates apparatus 
and method for detecting ice on a flight surface by using a video camera 
to detect effect surface color differences which are processed to 
determine the presence of ice and the direction of a de-icing gun. 
U.S. Pat. No. 5,313,202 relates to ice detection by determining the latant 
heat release as water freezes between two surfaces of a roter blade 
aircraft or the like. 
SUMMARY OF THE INVENTION 
The present invention is directed to the detection of ice on flight 
surfaces by direct surface contact by detection probes that determines the 
ice presence by the relative conductivity and non-conductivity 
therebetween. The probes form a conductive loop in a simple electrical 
circuit having a source of power and circuit completion indicator.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIG. 1 of the drawings, the present invention utilizes the 
principal of surface conductivity to indicate the presence of a 
non-conductive condition such as ice on a wing surface 10 where ice is 
expected to form. Referring now to FIGS. 1, 3, 5, 6, and 7 of the drawings 
an ice probe 11 can be seen as chosen for illustration comprising 
telescopically extensible tubular body members 12 and 13. A handle portion 
14 is positioned on the tubular body member 12's free end having a power 
cell chamber 16 therein. The power cell chamber 16 is configured similar 
to a simple battery powered flashlight wherein batteries are held and the 
enclosure forms part of the power circuit. 
Referring specifically to FIG. 5 of the drawings, the power cell chamber 16 
can be seen having a contact spring 17 engaging a battery 18 with a lead 
wire 19 extending therefrom. A threaded metal end cap 20 is engageable 
with a battery terminal 21 and a conductive metal housing 22 that 
interconnects with a lead wire 23. The inner engaging tubular members 12 
and 13 are typically of non-conductive material forming a passageway for 
the lead wires 19 and 23 that are connected to a probe deployment assembly 
24 best seen in FIGS. 5, 6, and 7 of the drawings. 
The probe deployment assembly 24 housed in the tubular member 13 inwardly 
of its free end at 25 has a support terminal activation button 26 that 
extends outwardly from the tubular element through a deployment slot 27 
best seen in FIG. 7 of the drawings. An apertured guide disk 28 is fitted 
within the tubular element 13 and acts as a support and guide for a pair 
of conductivity probes 29 and 30 as well as a light assembly 31. The 
probes 29 and 30 extend outwardly through angular guide bores 30A that 
define an angular inclination from the longitudinal axis of the tubular 
element 13 as the probes 29 and 30 extend therefrom. 
The probes 29 and 30 are of a spring wire composition with a curved return 
end configuration at 32 as they are deployed, see FIGS. 1, 4, and 6 of the 
drawings. 
In this example, the probe wire 29 is conducted to the wire lead 23 with 
the remaining probe wire 30 electrically connected to the light assembly 
31 via the probe deployment assembly 24. The light assembly 31 has a 
spring band 32 extending through a slot 33 in the support end guide disk 
28. A light bulb 34 is positioned on the free end of the spring band 32 
and is electrically interconnected with said probe wires 29 and 30 through 
the wire deployment assembly 24 by conductive portions 35 and 36 of the 
band 32 defined by respective insulating strips 37 and 38 therebetween as 
will be well understood by those skilled in the art and as best seen in 
FIG. 8 of the drawings. 
In operation, the probe wires 29 and 30 and indicator light assembly are 
deployed by advancement of the activation button 26 as illustrated in FIG. 
6 of the drawings and in broken lines in FIG. 5 of the drawings. The 
deployed probe wires 29 and 30 can then be passed over the wing surface 10 
as best seen in FIG. 2 of the drawings thus completing the lighting 
circuit 40 as seen in FIG. 3 of the drawings by the relative conductivity 
of the wing surface therebetween. The light circuit 40 defines a simply 
lighting configuration with a source of power (battery 18) interconnected 
to the light bulb 34 by the lead wires with an equivalent switch element 
formed by the spaced probe wires 29 and 30 as hereinbefore described. 
Upon loss of conductivity between the probe wires as will occur when passed 
over ice the light circuit is broken and the light 34 goes out indicating 
a possible icing event. 
Referring back again to FIGS. 2 and 4 of the drawings, an alternate wing 41 
configuration can be seen wherein the wing 41 is non-conductive having 
spaced parallel conductive strips on its wing surface 43 at critical areas 
which are prone to icing. The conductive strips 42 can be a coating of 
special paint surface commercially available as an apoxy copper 
conductivity coating series 599-Y1317, manufactured by Spraylat Corp. of 
Mount Vernon, N.J. which is comprised of a two component apoxy system in 
various thickness degrees which defines the effective conductivity of the 
material. 
Operation of the ice probe 11 on the alternative wings 41 is the same as 
hereinbefore described except that the probe wires 29 and 30 are dragged 
over the plurality of spaced conductivity strips 40 so that the operator 
gets an on/off light pattern as the light 40 circuit is closed an open 
respectively as illustrated by the probe's position in FIG. 4 indicated as 
closed in solid lines and open in broken lines. 
It will be evident from the above description that the ice probe 11 of the 
invention is fail safe since any component failure will cause open light 
condition warning the operator that either ice is present or the device 
has failed. 
A simple conductivity test of the ice probe 11 can easily be made by 
pushing the respective spaced probe elements 29 and 30 together completing 
the circuit 40 as hereinbefore described. 
It will be understood that the present invention is not limited by the 
scope of the specification since modifications and changes may be made 
therein without departing from the spirit of the invention and the scope 
is specifically directed towards the claims as herein follows: