A number of sealants are provided that are resistant to degradation by aircraft fluids. In some embodiments, the sealants are resistant to degradation by Jet A fluid and at least one of the three types of hydraulic fluids typically used in aircraft. These embodiments are also typically cure in place from a two part polyurethane or polyurea mix, with cure to a visibly clear coating. In some embodiments, they may be sprayed on an aircraft surface or applied by hand (brush or injectable). In other of these embodiments, the sealants comprise, at least in part, a cured, soft, tacky polyurethane gel that is resistant to at least one of a synthetic hydrocarbon based or mineral oil based hydraulic fluid.

A system for controlling an environment within a fuel tank is provided. The system includes a conduit with a plurality of vents, wherein the conduit defines a path through the fuel tank, and wherein the conduit is configured to direct a flow of air along the path and out the plurality of vents.

A system for controlling an environment within a fuel tank is provided. The system includes a conduit with a plurality of vents, wherein the conduit defines a path through the fuel tank, and wherein the conduit is configured to direct a flow of air along the path and out the plurality of vents.

An aircraft joint between overlapping first and second components includes a fastener assembly. The fastener assembly includes a threaded fastener and a boss having an outer diameter and a threaded internal bore. The boss is fixedly attached to the second component at the overlap region. The first component has a through hole having a diameter sized to receive the outer diameter of the boss. The boss is received in the through hole from a first side of the first component. The fastener extends through the through hole from a second side of the first component opposite the first side. The fastener is threadably received in the internal bore of the boss and reacts against the second side of the first component to fasten the first component to the second component.

A method of detecting a leak source within a tank includes coupling a first seal member to an external surface of the tank around an external leak location and coupling a second seal member to the external surface around a perimeter of the first seal member to define a gap between the first seal member and the second seal member. The method also includes coupling a sealing membrane to the first and second seal members such that a first cavity is at least partially defined within the perimeter of the first seal member and such that a second cavity is at least partially defined between the first seal member and the second seal member. The gap at least partially defines the second cavity. The method further includes applying a vacuum to the second cavity and injecting a detectable gas into the first cavity.

Provided are multi-tread vehicles and methods of operating such vehicles to access small interior spaces. A multi-tread vehicle may include two or more tread sections such that each pair of adjacent tread sections is interconnected by a connector section. Furthermore, each pair may have one or more degrees of articulations, such as being pivotable with respect to each other around one or more axis and/or being bendable with respect to each other around one or more axis. These articulation degrees may be provided by the connector section and/or by couplings between the connector section and each tread section. In some embodiments, each tread section may include two portions detachably coupled to each other. This detachable coupling may be used for disassembly of the multi-tread vehicle after or even during its use, for example, when only a portion of the vehicle needs to be retrieved from an interior space.

Provided are multi-tread vehicles and methods of operating such vehicles to access small interior spaces. A multi-tread vehicle may include two or more tread sections such that each pair of adjacent tread sections is interconnected by a connector section. Furthermore, each pair may have one or more degrees of articulations, such as being pivotable with respect to each other around one or more axis and/or being bendable with respect to each other around one or more axis. These articulation degrees may be provided by the connector section and/or by couplings between the connector section and each tread section. In some embodiments, each tread section may include two portions detachably coupled to each other. This detachable coupling may be used for disassembly of the multi-tread vehicle after or even during its use, for example, when only a portion of the vehicle needs to be retrieved from an interior space.

A method, apparatus, and system for testing a fuel tank for an aircraft. Electrical power is sent to an optical data concentrator for the fuel tank for the aircraft from a power supply such that the optical data concentrator sends optical signals to optical sensors inside the fuel tank through optical fibers connecting the optical data concentrator to the optical sensors. The electrical power is sent during a phase of manufacturing of the aircraft. Test data is received from the optical data concentrator by a computer system. The test data is based on optical response signals received from the optical sensors. A determination of states for the optical sensors is made by the computer system using the test data. A graphical indication of the states determined for the optical sensors inside the fuel tank is displayed by the computer system in a graphical user interface on a display system.

A method of detecting a leak source within a tank includes coupling a first seal member to an external surface of the tank around an external leak location and coupling a second seal member to the external surface around a perimeter of the first seal member to define a gap between the first seal member and the second seal member. The method also includes coupling a sealing membrane to the first and second seal members such that a first cavity is at least partially defined within the perimeter of the first seal member and such that a second cavity is at least partially defined between the first seal member and the second seal member. The gap at least partially defines the second cavity. The method further includes applying a vacuum to the second cavity and injecting a detectable gas into the first cavity.

A self-forming sealant system forms a seal between two parts or between a fastener and a part of a structure. In forming the seal, a first finish having a high surface energy is applied to the joint between the two parts or is applied to the fastener and the part. A second finish having a low surface energy is then applied adjacent to the area where the first finish was applied. A sealant is then applied to the joint between the two parts or the fastener and the part, where the sealant migrates to the joint or fastener coated with the first finish having the high surface energy and away from the areas adjacent the joint or the fastener coated by the second finish having the low surface energy.