Aircraft compartment overheat indicator, system, and method

1 . A self-powered aircraft compartment thermal indicator comprising:

an indicator body comprising an indicator body length, said indicator body comprising:

an indicator body interior;

an indicator body exterior;

an indicator body first end;

an indicator body second end;

an indicator body second end base;

an internal piston, said internal piston comprising a piston base, said piston base comprising a piston base first side and a piston base second side, said internal piston further comprising a piston rod, said piston rod comprising a piston rod first end and a piston rod second end, said piston rod first end in communication with a visually detectable signaling device, said piston rod second end at least in communication with the piston base first side;

an indicator body wall, said indicator body wall extending along the indicator body length from the indicator body first end to the indicator body second end, said indicator body wall comprising an indicator body wall outer surface at the indicator body exterior and an indicator body wall inner surface at the indicator body interior;

a battery compartment, said battery compartment comprising a battery compartment base, said battery compartment defined by the battery compartment base and the indicator body wall inner surface;

an indicator body first chamber defined by the indicator body wall inner surface, the piston base first side, and the battery compartment base, said indicator body first chamber comprising a frangible container, said frangible container housing a volume of battery electrolyte;

an indicator body second chamber defined by the indicator body wall inner surface and the piston base second side, said indicator body second chamber comprising a spring, said spring comprising a spring first end fixedly attached to the piston base, said spring further comprising a spring second end located immediately adjacent the indicator body second end base; and

a degradable retainer, said degradable retainer in communication with said spring, said degradable retainer configured to retain the spring in a compressed spring state within a first temperature range, said degradable retainer configured to degrade at a threshold temperature, said threshold temperature within a second temperature range, said degradable retainer further configured to retain the spring in a compressed spring state while at the first temperature range, said degradable retainer further configured to release the spring from the compressed spring state toward an expanded spring state at the threshold temperature in the second temperature range; and

wherein said threshold temperature is higher than the first temperature range.

2 . The self-powered aircraft compartment thermal indicator of claim 1 , wherein the visually detectable signaling device is at least one of a light fixture and a light-emitting diode.

3 . The self-powered aircraft compartment thermal indicator of claim 1 , wherein said battery compartment further comprises a plurality of battery plates.

4 . The self-powered aircraft compartment thermal indicator of claim 3 , wherein the battery plates in combination with the electrolyte form a battery configured to deliver an electrical current.

5 . The self-powered aircraft compartment thermal indicator of claim 4 , wherein the battery is a fuze battery.

6 . The self-powered aircraft compartment thermal indicator of claim 1 , wherein the degradable retainer comprises at least one of a low temperature alloy, and a wax, said degradable retainer comprising a melting point ranging from about 140° F. to about 165° F.

7 . The self-powered aircraft compartment thermal indicator of claim 6 , wherein the low temperature alloy comprises at least one of bismuth, lead, tin, indium, cadmium, thallium, gallium, and combinations thereof, said low temperature alloy comprising a melting point ranging from about 140° F. to about 165° F.

8 . The self-powered aircraft compartment thermal indicator of claim 7 , wherein the low temperature metal alloy comprises at least one of rose's metal, cerrosafe, wood's metal, field's metal, cerrolow 136, cerrolow 117, gallium, and combinations thereof.

9 . The self-powered aircraft compartment thermal indicator of claim 1 , further comprising a heat-directing tube, said heat-directing tube comprising a heat-directing tube first end, a heat-directing tube second end, and a heat-directing tube wall, said heat-directing tube first end integrated into the indicator body second chamber, said heat-directing tube wall positioned immediately adjacent to the degradable retainer.

10 . An aircraft wing component comprising the self-powered aircraft compartment thermal indicator of claim 1 .

11 . An aircraft comprising the self-powered aircraft compartment thermal indicator of claim 1 .

12 . An aircraft compartment temperature indication system for visually detecting at an aircraft exterior an above-threshold temperature within an aircraft compartment proximate to the aircraft exterior, the aircraft compartment temperature indication system comprising:

a self-powered aircraft compartment thermal indicator removably attached to an aircraft component, said self-powered aircraft compartment thermal indicator comprising:

an indicator body comprising an indicator body length, said indicator body comprising:

an indicator body interior;

an indicator body exterior;

an indicator body first end visible at an aircraft exterior;

an indicator body second end positioned within the aircraft compartment and extending into the aircraft compartment a selected distance from the indicator body first end;

an indicator body second end base;

an internal piston, said internal piston comprising a piston base, said piston base comprising a piston base first side and a piston base second side, said internal piston further comprising a piston rod, said piston rod comprising a piston rod first end and a piston rod second end, said piston rod second end at least in communication with the piston base first side;

an indicator body wall, said indicator body wall extending along the indicator body length from the indicator body first end to the indicator body second end, said indicator body wall comprising an indicator body wall outer surface at the indicator body exterior and an indicator body wall inner surface at the indicator body interior;

a battery compartment configured to house a battery, said battery configured to deliver an electrical current along an electrical circuit, said battery compartment comprising a plurality of battery plates, said battery compartment comprising a battery compartment base, said battery compartment defined by the battery compartment base and the indicator body wall inner surface;

an indicator body first chamber defined by the indicator body wall inner surface, the piston base first side, and the battery compartment base, said indicator body first chamber comprising a frangible container, said frangible container housing a volume of battery electrolyte;

an indicator body second chamber defined by the indicator body wall inner surface and the piston base second side, said indicator body second chamber comprising a spring, said spring comprising a spring first end fixedly attached to the piston base, said spring further comprising a spring second end located immediately adjacent the indicator body second end base; and

a degradable retainer, said degradable retainer in communication with said spring, said degradable retainer configured to retain the spring in a compressed spring state within a first temperature range, said degradable retainer configured to degrade at a threshold temperature, said threshold temperature within a second temperature range, said degradable retainer further configured to retain the spring in a compressed spring state while at the first temperature range, said degradable retainer further configured to release the spring from the compressed spring state toward an expanded spring state at the threshold temperature in the second temperature range;

a visually detectable signaling device located at the indicator body first end, said visually detectable signaling device in communication with the electrical circuit, said visually detectable signaling device further configured to be visually detectable at the aircraft exterior; and

wherein said visually detectable signaling device is configured to activate at and above a threshold temperature.

13 . The aircraft compartment temperature indication system of claim 12 , wherein the visually detectable signaling device comprises at least one of a light fixture and a light-emitting diode.

14 . The aircraft compartment temperature indication system of claim 12 , wherein the visually detectable signaling device is configured to emit a beam of light in response to the indicator second end being exposed to a threshold temperature ranging from about 140° F. to about 165° F.

15 . The aircraft compartment temperature indication system of claim 12 , wherein the self-powered aircraft compartment thermal indicator is a removable aircraft compartment thermal indicator.

16 . The aircraft compartment temperature indication system of claim 12 , wherein the battery is a fuze battery, said fuze battery configured to form and deliver an electrical current at the threshold temperature.

17 . A method for indicating at an aircraft exterior a temperature exceeding a threshold temperature within an aircraft component compartment, the method comprising:

positioning a self-powered aircraft compartment thermal indicator in an aircraft component, said self-powered aircraft component comprising an aircraft component outer surface, said aircraft component outer surface positioned adjacent to an aircraft compartment, said self-powered aircraft compartment thermal indicator comprising:

an indicator body comprising an indicator body length, said indicator body comprising:

an indicator body interior;

an indicator body exterior;

an indicator body first end;

an indicator body first end through opening;

an indicator body second end;

an indicator body second end base;

an internal piston, said internal piston comprising a piston base, said piston base comprising a piston base first side and a piston base second side, said internal piston further comprising a piston rod, said piston rod comprising a piston rod first end and a piston rod second end, said piston rod second end at least in communication with the piston base first side, said piston rod first end comprising a light-emitting fixture;

an indicator body wall, said indicator body wall extending along the indicator body length from the indicator body first end to the indicator body second end, the indicator body second end base, said indicator body wall comprising an indicator body wall outer surface at the indicator body exterior and an indicator body wall inner surface at the indicator body interior;

a battery compartment comprising a plurality of battery plates, said battery compartment comprising a battery compartment base, said battery compartment defined by the battery compartment base and the indicator body wall inner surface;

an indicator body first chamber defined by the indicator body wall inner surface, the piston base first side, and the battery compartment base, said indicator body first chamber comprising a frangible container, said frangible container housing a volume of battery electrolyte;

an indicator body second chamber defined by the indicator body wall inner surface and the piston base second side, said indicator body second chamber comprising a spring, said spring comprising a spring first end fixedly attached to the piston base, said spring further comprising a spring second end located immediately adjacent the indicator body second end base; and

a degradable retainer, said degradable retainer in communication with said spring, said degradable retainer configured to retain the spring in a compressed spring state at a first temperature range, said degradable retainer configured to degrade at a threshold temperature, said threshold temperature within a second temperature range, said degradable retainer further configured to release the spring from the compressed spring state while at the first temperature range to an expanded spring state at the threshold temperature in the second temperature range, said threshold temperature is higher than the first temperature range;

degrading the degradable retainer at the threshold temperature;

releasing the spring from the compressed spring state to the expanded spring state;

delivering the piston from a piston initial position to a piston deployed position;

rupturing the frangible container to form a ruptured frangible container;

releasing from the ruptured frangible container at least a portion of the volume of battery electrolyte;

directing at least a portion of the volume of battery electrolyte into the battery compartment to form a battery, said battery configured to produce electrical current;

directing the piston rod first end through the indicator body first end through-opening to a selected distance beyond the aircraft component outer surface; and

directing an electrical current from the battery to activate the light-emitting fixture to emit light from the light-emitting fixture.

18 . The method of claim 17 , further comprising visually detecting light emitted from light-emitting fixture at the aircraft exterior.

19 . The method of claim 18 , further comprising removably positioning the self-powered aircraft compartment thermal indicator in the aircraft component.

20 . The method of claim 18 , wherein visually detecting at the aircraft exterior light from the self-powered aircraft compartment thermal indicator evidences at least a threshold temperature within the aircraft component compartment.