Patent Description:
<CIT> describes an unmanned aerial vehicle that includes a sensing system for the detection and limited identification of biological agents. The system incorporates elements that enable it to obtain an air sample, extract particulates from the air sample and retain them on a stationary-phase collection media, expose the particulates to electromagnetic radiation, and monitor the particulates for fluorescent emissions. To the extent that fluorescent emissions are detected and exceed a predetermined value, an alarm is triggered. In some embodiments, in addition to performing real-time analyses on the extracted particulates, the collection media is removed from the system and the sample is subjected to more detailed analysis via additional equipment. Various sample-collecting regions on the collection media are "time stamped" or "location stamped" so that it can determined when and/or where each sample that is being analyzed "off-line" was obtained.

<CIT> describes a collection device for a substance, and methods related to collecting thereof.

<CIT> describes an environmental monitoring UAV system comprises a drone provided with an air monitoring platform that is adapted for taking air sample(s) by enforcing air to flow through or into at least one sampling medium, during the flight of said drone.

<CIT> describes a method for determining emissions in an exhaust plume produced by a combustion engine of a vessel during cruise of the vessel, said emissions comprising the presence or concentration of carbon dioxide (C02) and/or sulphur dioxide (S02) and/or the count and size of particles. The position and distribution of the exhaust plume is determined or estimated on the basis of the position, bearing and speed of the vessel and further on the basis of meteorological data, such as wind direction and speed. An unmanned aerial vehicle (UAV), i.e. a so-called drone, is controlled to fly through the plume to make measurements of exhaust emissions of the vessel.

<NPL>, analyzes the size distribution and chemical composition of aerosol particles during a dust storm in the eastern Mediterranean. The data were obtained from airborne measurements during the Mediterranean Israeli Duct Experiment (MEIDEX). The chemical and physical properties of the particles are used as initial conditions for conducting a sensitivity simulation study.

<CIT> relates to engine maintenance and maintenance schedules for turbine engines in aircraft.

According to the present invention there is provided a method of establishing a fleet management plan for aircraft, the method comprising providing an environmental sampling system in an aircraft, the environmental sampling system including a collector that receives ambient aircraft air thereto when the aircraft flies, the collector retaining constituents from the air; after the aircraft has flown, collecting the constituents by either removing the collector from the aircraft or removing the constituents from the collector; analyzing the constituents to determine the amount of calcium- magnesium-aluminosilicate solids (CMAS) associated with the constituents; inspecting the aircraft engine components for CMAS degradation; and correlating the amount of CMAS collected in the environmental sampling system to an amount of degradation in aircraft engine components.

In an embodiment of any of the above embodiments, an environmental sampling system is provided in a plurality of aircraft, and the correlation of the amount of CMAS collected in the environmental sampling system and the amount of degradation in aircraft engine components is correlated to the flight times and flight paths for each aircraft.

In an embodiment of any of the above embodiments, the collecting of the constituents includes removing the collector from the aircraft or removing the constituents from the collector while the collector is on the aircraft.

In an embodiment of any of the above embodiments, the analyzing is selected from the group consisting of weighing the removable collector, performing an elemental analysis, performing x-ray analysis, extracting the constituents from the removable collecting using a carrier fluid, performing particle size analysis, and combinations thereof.

In an embodiment of any of the above embodiments, the inspection of aircraft engine components for CMAS degradation comprises measurement of wall thickness loss of a thermal barrier coating on an engine component.

In an embodiment of any of the above embodiments, the fleet management plan is adapted for use in establishing fleet management plans, warranty planning, material resource planning and placement for spare parts and overhaul schedules, provision of remaining useful life estimates, and/or provision of engine removal rate predictions.

According to a second aspect of the present invention there is provided an environmental sampling system comprising an aircraft component having a surface on which an air flow impinges when the aircraft component is in operation; and an accumulator including a chamber and an inlet tube that is open to the surface; wherein the inlet tube extends into the chamber and the aircraft component is a spinner.

In an embodiment of any of the above embodiments, the chamber includes one or more of a screen dividing an interior of the chamber into a first region and a second region.

In an embodiment of any of the above embodiments, the chamber includes a liquid in the second region.

In an embodiment of any of the above embodiments, the inlet tube opens at the second region.

In an embodiment of any of the above embodiments, the accumulator includes an outlet passage that opens at the first region, and a feed tube that opens at the second region.

<FIG> schematically illustrates a gas turbine engine <NUM> mounted on an aircraft <NUM> (shown schematically). The gas turbine engine <NUM> disclosed is a two-spool turbofan that generally incorporates a fan section <NUM>, a compressor section <NUM>, a combustor section <NUM> and a turbine section <NUM>. The fan section <NUM> drives air along a bypass duct B defined within a nacelle or case <NUM>, and also drives air along a core flow path C for compression and communication into the combustor section <NUM> then expansion through the turbine section <NUM>. Although depicted as a two-spool turbofan gas turbine engine in the disclosed non-limiting embodiment, the examples described herein are not limited to use with two-spool turbofans and the teachings may be applied to other types of turbine engines including but not limited to three-spool architectures.

In a further example, the engine <NUM> bypass ratio is greater than about six <NUM>:<NUM>, with an example embodiment being greater than about <NUM>:<NUM>, the geared architecture <NUM> is an epicyclic gear train, such as a planetary gear system or other gear system, with a gear reduction ratio of greater than about <NUM>:<NUM> and the low pressure turbine <NUM> has a pressure ratio that is greater than about <NUM>:<NUM>. In one disclosed embodiment, the engine <NUM> bypass ratio is greater than about <NUM>:<NUM>, the fan diameter is significantly larger than that of the low pressure compressor <NUM>, and the low pressure turbine <NUM> has a pressure ratio that is greater than about five <NUM>:<NUM>. The low pressure turbine <NUM> pressure ratio is characterized by a pressure measured prior to the inlet of low pressure turbine <NUM> as related to the pressure at the outlet of the low pressure turbine <NUM> prior to an exhaust nozzle. The geared architecture <NUM> may be an epicycle gear train, such as a planetary gear system or other gear system, with a gear reduction ratio of greater than about <NUM>: <NUM> and less than about <NUM>:<NUM>. It should be understood, however, that the above parameters are only exemplary of one embodiment of a geared architecture engine and that the present invention is applicable to other gas turbine engines including but not limited to direct drive turbofans.

A significant amount of thrust is provided by the bypass flow due to the high bypass ratio. The low fan pressure ratio as disclosed herein according to one non-limiting embodiment is less than about <NUM>:<NUM>.

When the aircraft <NUM> is in flight, the engine <NUM> ingests surrounding ambient air, a portion of which flows into the core flow path C and a remainder of which flows through the bypass duct B. The air may include entrained solids, such as dirt particles, insects, or other airborne debris, as well as gaseous compounds, such as sulfur-containing compounds (e.g., sulfur dioxide). Collectively, these solids and gaseous compounds, or constituents, may be referred to herein as foreign substances, i.e., substances besides nitrogen and oxygen in the air. Some foreign substances may be benign to engine health but others, such as gaseous sulfur compounds and calcium-magnesium-aluminosilicate solids (known as CMAS) from dirt, can cause degradation of engine components. For instance, the foreign substances can cause corrosion, spallation of coatings, or cracking that may reduce the useful life of an engine component. Heretofore, there has been an incomplete understanding of the quantity of foreign substances that are ingested into an engine and, therefore, no ability to utilize knowledge of ingested foreign substances as an input for engine or aircraft management. It is in this regard that the engine <NUM> and/or aircraft <NUM> includes an environmental sampling system <NUM> (hereafter "system <NUM>"), an example not according to the claimed invention is shown in <FIG>. As will be described herein, the system <NUM> (and variations thereof) provides the ability to capture and subsequently quantify foreign substances ingested into the engine <NUM>.

In general, the system <NUM> is located in the engine <NUM> and/or on the aircraft in a location that receives ambient air when the engine <NUM> and/or aircraft <NUM> is in operation, e.g., in flight. Non-limiting exemplary locations will be described in further detail below.

In the example illustrated in <FIG>, the system <NUM> includes a passage <NUM> and a removable collector <NUM> disposed in the passage <NUM>. As used herein, the term "removable" means that the collector <NUM> is able to be taken off of or out of the passage <NUM>, without destruction of the collector <NUM> (e.g., fracturing, chemically altering, etc.). In this regard, the collector <NUM> is temporarily secured in the passage <NUM>. The technique of securing is not particularly limited and may include, but is not limited to, fasteners, interference fits, and mechanical interlocking.

The passage <NUM> is in either the aircraft <NUM> or a component of the engine <NUM>, or if multiple systems <NUM> are used there may be multiple passages <NUM> in the engine <NUM>, the aircraft <NUM>, or both. The passage <NUM> defines an inlet 62a at a first region, designated at R1, and an outlet 62b at a second region, designated at R2. The location of the passage <NUM> with respect to the regions R1/R2 is selected such that, during operation of the aircraft <NUM> and engine <NUM>, the static pressure at region R1 is greater than the static pressure at region R2. This pressure differential causes flow of the air through the passage <NUM>, and thus also flow of the air through the collector <NUM>.

The collector <NUM> is configured to retain constituents (at least a portion of the foreign substances) from the air. In this regard, the collector <NUM> includes or is constituted of a rigid porous body <NUM>. As used herein, the term "rigid" means that the body <NUM> substantially maintains its shape under the aerodynamic forces imparted by the air flow through the body <NUM>.

<FIG> illustrates an example not according to the claimed invention of a representative portion of the body <NUM>. In this example, the body <NUM> has a reticulated structure that includes an interlaced network of pore walls or tendrils 66a that define there between a random arrangement of interconnected pores 66b. That is, the body <NUM> has an open porosity such that the air can flow there through.

The structure of body <NUM> with regard to the pores 66b is configured to capture and retain one or more target foreign substances and can be custom designed for the expected particle size that varies from <NUM> to <NUM> micrometers. As an example, the pores 66b have an average pore size (diameter) of <NUM> micrometer to <NUM> micrometers to capture particulate greater than <NUM> micron, the pore size of which can be determined by a known gas absorption technique. Such a pore size is adapted to capture and retain dirt particles in the air. Most typically, however, the average pore size may be from <NUM> micrometers to <NUM> micrometers.

The material from which the body <NUM> is formed is selected from a porous ceramic, a porous metal, a porous polymer, or combinations thereof. For instance, the material can be selected based on temperature, corrosion, and erosion requirements at the selected location of the passage <NUM>. Examples of ceramics include, but are not limited to, oxide ceramics such as aluminum-based oxides, zirconium-based oxides, silicon-based oxides or carbides. Examples include Nextel ceramic fiber blankets or silicon carbide fiber weaves. Ceramic can be used in locations that have high temperature, severe corrosion conditions, or severe erosion conditions. Examples of metal or metal alloys include, but are not limited to, nickel or cobalt alloys, stainless steel, aluminum or alloys thereof, or metal foams that can be manufactured by casting, sintering, or plasma-spraying. One such example would be porous material made of sintered metal fibers which has a trade name of Feltmetal. Metals can be used in locations that have intermediate temperature, intermediate or low corrosion conditions, or intermediate or low erosion conditions. Examples of polymers include, but are not limited to, polyimide, polyamides, polyesters, and thermosetting plastics, for example melamine foams. Polymers can be used in locations that have low temperature, intermediate or high corrosion conditions, or low erosion conditions. The materials can be selected such that measurable corrosion of the porous material at lower temperatures can be determined from standard laboratory techniques, and this can be directly related to corrosion at higher temperature on aircrafts parts through analytical or empirical techniques.

The body <NUM> captures and retains foreign substances, such as dirt, from air that flows through the body <NUM> when the engine <NUM> and/or aircraft <NUM> is in operation. For instance, the pressure differential causes air flow through the passage <NUM> and body <NUM>. Particles entrained in the air infiltrate the body <NUM> via the pores 66b. The pores 66b define a circuitous path through the body <NUM> such that the air can escape and flow to the outlet 62b of the passage <NUM>. The walls/tendrils 66a of the body <NUM>, however, impede the movement of particles through the body <NUM>. Particles become wedged into the pores 66b and are thus retained in the body <NUM>. As particles are retained, the retained particles can then also serve to block movement of additional particles. In this manner, but not limited thereto, particles are captured and retained in the body <NUM>.

After the aircraft <NUM> has flown, the retained constituents (foreign substances) are collected by removing the collector <NUM> from the passage <NUM> and aircraft <NUM>. The constituents are then analyzed to determine at least one characteristic associated with the constituents. For instance, the removed collector <NUM> may be transferred to a laboratory, analysis station, or the like for analysis. The characteristic or characteristics determined in the analysis can include, but are not limited to, weight analysis, elemental analysis, crystallographic analysis, and particle size analysis. Weight analysis may be performed by weighing the removed collector <NUM> and comparing the weight to the initial weight of the collector <NUM> prior to its use in the engine <NUM> or aircraft <NUM>. The weight analysis thereby provides a measure of the amount of foreign substances collected by the collector <NUM>. Elemental analysis may be performed by energy dispersive spectroscopy (EDS) or x-ray fluorescence. The elemental analysis thereby provides an indication of the chemical composition of the foreign substances. The crystallographic analysis can be performed by x-ray diffraction and provides an indication of crystal structure, or lack thereof (amorphous). The particle size analysis can be performed by microscopy and provides an indication of the size of particles retained in the collector <NUM>.

One or more foreign substances can also be extracted from the collector <NUM> for analysis. For instance, foreign substances, such as salts, are extracted from the body <NUM> using a carrier fluid, such as but not limited to, water, alcohol or other polar solvent, or hexane or other non-polar solvent. The carrier fluid may dissolve all or a portion of the foreign substances and/or may physically "wash" all or a portion of the foreign substances without dissolution. The extracted foreign substances can then be analyzed by one or more of the techniques above and/or other techniques, such as but not limited to, wet chemical analysis. Overall corrosion rates can be measured by a weight comparison after all material is removed.

Subsequently, the information collected through the analysis is combined with one or more of engine operating conditions, flight path(s) (e.g. city pairs), and engine component distress to establish a correlation between one or more of the characteristics of the foreign substances and deterioration of the engine <NUM>. For example, to establish such a correlation, one or more characteristics of the foreign substance are determined as above and distress on one or more engine components of the engine <NUM> is characterized. The characterization of the distress can include, but is it not limited to, characterization of coating spallation, corrosion, cracking, or the like. Compositional information of the foreign substance may be compared to compositional information of the distressed component, to link the foreign substance as a cause of the distress. One or more relationships can then be established between the characterization of the foreign substance and the characterization of the distress. Such relationships can also be combined with engine operating conditions (e.g., number of flights) and/or flight path to estimate, for example, the amount of foreign substance ingested per flight for a particular route and/or incremental distress to one or more engine components. Such correlations can then further be used to generate remaining useful life estimates and/or engine removal rate predictions without the need for engine teardown or detailed inspection of the turbomachinery and cavities.

In one example, flight times and flight paths are recorded for numerous aircraft having collectors <NUM>. The collectors <NUM> are removed from the aircraft and analyzed for amount of CMAS, which is expected to range from a relatively low amount to a relatively high amount. Engine components (e.g., turbine vanes or blades) from the same aircraft/engines are inspected for CMAS degradation. From this, a relationship is established between the amount of CMAS in the collectors <NUM> and observed level of CMAS degradation in the engine components. In general, the relationship is such that higher amounts of CMAS in the collectors <NUM> corresponds to higher amounts of degradation in the engine components. The amount of CMAS determined in subsequent collectors <NUM> on other aircraft can then be compared to the established relationship to estimate the level of CMAS degradation. The estimates can, in turn, be used to trigger inspection, engine removal, or refurbishing if a threshold amount is determined. The relationship can also involve correlation to particular flight paths, to determine paths that have more or less CMAS and, as a result, more or less degradation. Additionally or alternatively, the relationships can be used to establish fleet business agreements, such as for operators in typically hot and dirty conditions where engines are severely distressed. Additionally or alternatively, the relationships can be used to establish fleet management plans, such as for operators in typically hot and dirty conditions where engines are severely distressed after relatively short time exposures. Additionally or alternatively, the relationships can be used to establish material resource planning and placement for spare parts and overhaul schedules.

Table <NUM> illustrates a further example of a correlation between a weight characterization of collected foreign substance and engine component distress. Intervals (in days) are shown at zero days, <NUM> days, <NUM> days, <NUM> days, and <NUM> days of weight characterizations from, respectively, four different collectors <NUM>, which are flown over the same flight path. The distress characterization is of wall thickness loss of a thermal barrier coating on the same engine component from the engines associated with the four collectors <NUM>. The interval-weight contaminant characterization and the wall thickness distress characterization are used to determine interval and accumulated data. Such data could then be plotted on a graph, which here from zero time would be an upward curved line. This data set is an example of what would be used to plot accumulated wall thickness loss vs. accumulated interval-weight of contaminant. The plot could then be used to predict how many oz-hours (g-hours) remain on an engine before the wall thickness reaches a designated minimum.

As indicated above, the system <NUM> is located in the engine <NUM> and/or on the aircraft <NUM> in a location that receives ambient air when the engine <NUM> and/or aircraft <NUM> is in operation, e.g., in flight. Example locations can include, but are not limited to, a wing airfoil, a spinner, a compressor bleed line, a bypass duct, or a gas turbine engine nacelle inlet or fan bypass duct. Locations in the engine <NUM>, and particularly in the spinner and compressor bleed line, may be especially representative of air ingested into the core engine.

<FIG> shows example locations of the system <NUM>, not according to the claimed invention, in a compressor bleed line <NUM>, the bypass duct B, and engine inlet <NUM>. <FIG> illustrates an example of the system <NUM>, not according to the claimed invention, in a fan inlet spinner <NUM>. The spinner <NUM> is the aerodynamic cone at the hub of the fan <NUM>. In this example, the inlet 62a of the passage <NUM> is located at or near the stagnation point P of the spinner <NUM>. Such a location may facilitate ingestion of air into the passage <NUM> from a ram air effect, as opposed to locations where the air flows across the inlet 62a. The outlet 62b is located on the spinner <NUM> at an axially offset location downstream from the inlet 62a. At such a location, the region R2 is at a lower static pressure than region R1.

<FIG> illustrates an example of the system <NUM>, not according to the claimed invention, in a wing airfoil <NUM>. In this example, the airfoil <NUM> is an aircraft wing of the aircraft <NUM>. In this example, like the spinner <NUM>, the inlet 62a of the passage <NUM> is located at or near the stagnation point P of the airfoil <NUM>. In variations of the above examples, inlet 62a in the spinner <NUM> or in the airfoil <NUM> is offset from the stagnation point determined to be the most favorable location for correlation to foreign substances ingested into the engine core.

<FIG> illustrates a further example of the system <NUM>, not according to the claimed invention, that can be implemented in any of the above examples. In this example, the system <NUM> includes a valve <NUM> disposed in the passage <NUM>. As shown, the valve <NUM> is at the inlet 62a, although in variations the valve is located aft of the inlet 62a, or even at the outlet 62b. One example of the valve <NUM> is a gate-type, ball, butterfly, slider or flapper valve. The valve <NUM> can be selectively opened or closed to, respectively, allow or prevent air from flowing in the passage <NUM>. For example, the state of the valve <NUM> (open or closed) depends on one or more flight conditions. For instance, at relatively low altitudes, there are more insects than at relatively high altitudes. If insects are not of concern as a target foreign substance to collect in the collector <NUM>, the valve <NUM> can be operated such that it is closed at low altitudes and opened at high altitudes. Such a control scheme can be used to reduce or avoid plugging up the collector <NUM> with non-target foreign substances. Likewise, the valve can be opened only on particular flight paths of interest or only on particular legs of flight paths.

<FIG> illustrates a further example of the system <NUM>, not according to the claimed invention, that can be implemented in any of the above examples. In this example, the collector <NUM> includes a plurality of rigid porous bodies <NUM> that are arranged in series through the passage <NUM>. In this disclosure, like reference numerals designate like elements where appropriate and reference numerals with the addition of one-hundred or multiples thereof designate modified elements that are understood to incorporate the same features and benefits of the corresponding elements. As shown, the bodies <NUM> are spaced apart, although in variations the bodies are contiguous or adjoined. The bodies may be individually adapted to capture and retain different target foreign substances and/or different sizes of foreign substances. For instance, the average pore size (diameter) of the bodies successively decreases from the inlet 62a to the outlet 62b. Thus, larger particles are caught and retained by the first body <NUM>, intermediate sized particles by the second body <NUM>, and smaller particles by the third body <NUM>.

<FIG> illustrates another example of an environmental sampling system <NUM> not according to the claimed invention. In this example, rather than the collector <NUM> (or in addition to the collector <NUM>), the system <NUM> includes a gas detector <NUM> disposed in the passage <NUM>. While the collector <NUM> is configured to capture and retain solids, the gas detector <NUM> is configured to measure gaseous foreign substances ingested through the passage <NUM>.

<FIG> illustrates one example, not according to the claimed invention, in which the gas detector is a gas probe <NUM>. The gas probe <NUM> is operable to collect samples of the air flowing through the passage <NUM>. The gas probe <NUM> may be connected with an analyzer <NUM>. For example, the gas probe <NUM> collects samples and transfers the samples to the analyzer <NUM>, which characterizes the sample gas. For instance, the characterization can include identification of the presence or not of one or more target gaseous compounds and/or measurement of the concentration of one or more target gaseous compounds.

<FIG> illustrates one example, not according to the claimed invention, in which the gas detector is a gas sensor <NUM>. The gas sensor <NUM> is operable to detect the presence of one or more target gaseous foreign substances in the air flowing through the passage <NUM>. The gas sensor <NUM> may be connected with a controller <NUM>. For example, the gas sensor <NUM> detects the presence of one or more target gaseous foreign substances and transmits electrical signals to the controller <NUM>. The signals may represent the presence and concentration of the one or more target gaseous foreign substances in the air flowing through the passage. In such gas detectors, similar to the solids collection described above, data can be collected on the one or more target gaseous foreign substances and correlated to distress of one or more engine components. For instance, periodic concentrations of one or more target gaseous foreign substances are taken and used to determine interval and accumulated data as described above with reference to Table <NUM>.

<FIG> illustrates another example environmental sampling system <NUM>. In this example, the system <NUM> includes a collector or accumulator <NUM>. As shown, the accumulator <NUM> is in the spinner <NUM>, although it is to be understood that the accumulator <NUM> can alternatively be in other locations as described herein for the system <NUM>. The spinner <NUM>, or other aircraft component, has a surface 74a on which an air flow impinges when the aircraft component is in operation. The accumulator <NUM> is configured to receive the air and accumulate foreign substances, particularly solids, from the air.

The accumulator <NUM> includes a chamber <NUM>, an inlet tube 84a that is open to the surface 74a, and an outlet passage 84b. The inlet tube <NUM> extends into the chamber <NUM>.

Air and entrained foreign substances flow into the chamber via the inlet tube <NUM>. Inside the chamber <NUM>, the air swirls and diffuses forward around the sides of the inlet tube <NUM>. The slowing of the air flow causes the solids to fall out of the flow inside the chamber <NUM>. Since the inlet tube <NUM> extends into the chamber <NUM> it is difficult for the solids to escape. The air then exits through the outlet passage 84b. The solids thus accumulate inside the chamber <NUM>. Additionally, if the accumulator <NUM> is in the spinner <NUM> or other rotating structure, the rotation may create a centrifugal effect that throws the particles outwards, thereby further trapping the particles inside the chamber <NUM>.

The accumulated foreign substances in the chamber <NUM> can be collected while the accumulator <NUM> remains on the component. For example, the substances can be removed via a vacuum and then submitted for analysis as described above. Alternatively, the accumulator <NUM> can be removed from the component and the substances can then subsequently be removed from the chamber <NUM> for analysis.

<FIG> illustrate another example environmental sampling system <NUM>, not according to the claimed invention, that is a variation of the system <NUM>. In this example, the system <NUM> is in a component <NUM>, such as an engine nacelle or case structure. The system <NUM> includes an accumulator <NUM> that has a chamber <NUM>, an inlet tube 184a that is open to a surface 174a on which an air flow impinges when the aircraft component is in operation, and an outlet passage 184b. The inlet tube 184a may have a scoop <NUM>, such as a low-drag inlet design, for feeding air flow into the system <NUM>. In one example, the scoop <NUM> is located aft of the fan <NUM>.

As shown in <FIG>, the chamber <NUM> includes a screen <NUM> that divides and separates the interior region of the chamber <NUM> into a first region FR1 and a second region FR2. The second region FR2 is at least partially filled with a liquid, L, such as but not limited to water and water/anti-freeze mixtures. A feed tube <NUM> may be used to fill, empty, or circulate the liquid. A filter screen <NUM> can be used over the feed tube <NUM> to prevent foreign substances, particularly particles, from escaping the chamber <NUM>.

In use air flow and entrained foreign substances are fed into the chamber <NUM> via the inlet tube 184a. The inlet tube opens in the second region FR2. Any entrained foreign substance is captured and retained by the liquid. The air then flow through the screen <NUM> and is discharged through the outlet passage 184b. The foreign substances thus accumulate in the chamber <NUM>. The accumulated foreign substances can be collected by removing the chamber <NUM> from the component and the substances can then subsequently be removed from the chamber <NUM> for analysis as described above. Alternatively, the substances can be collected while the accumulator <NUM> remains on the component by collecting the liquid/substance through the tube <NUM> and the substances can then subsequently be submitted for analysis. Additionally or alternatively, the screen <NUM> and/or filter <NUM> may serve to capture and retain foreign substances. In this regard, the substances can also be collected from the screen <NUM> and/or filter <NUM> for analysis.

The examples described above also represent examples of a method <NUM> of environmental sampling, which is depicted schematically in <FIG>. Generally, the method <NUM> includes step <NUM> in which an environmental sampling system is provided in an aircraft. For instance, the provision of the system can include actual furnishing of the system or mere presence or use of such a system in an aircraft. At step <NUM>, after the aircraft has flown, the constituents (foreign substances) are collected by either removing the collector from the aircraft or removing the constituents from the collector. An example of removing the collector is described above with reference to collector <NUM>. An example of removing constituents from a collector is described above with reference to accumulator <NUM>. At step <NUM> the constituents are analyzed, as also described earlier herein, to determine at least one characteristic associated with the constituents. In some examples, the method <NUM> may conclude there. In further examples, the method <NUM> may additionally include correlating the characteristic to deterioration <NUM> of a gas turbine engine, which is described above with reference to engine component distress. It is to be further understood that the earlier examples of the systems and their operations herein also constitute examples of aspects of the method <NUM>. In further examples, the method may additionally include a predictive assessment step <NUM>. In step <NUM> the relationships herein above are used to establish fleet management plans and be used to establish warranty planning, material resource planning and placement for spare parts and overhaul schedules, remaining useful life estimates, and/or engine removal rate predictions.

Claim 1:
A method (<NUM>) of establishing a fleet management plan for aircraft, the method (<NUM>) comprising:
providing an environmental sampling system (<NUM>) in an aircraft (<NUM>), the environmental sampling system (<NUM>) including a collector (<NUM>) that receives ambient aircraft air thereto when the aircraft (<NUM>) flies, the collector (<NUM>) retaining constituents from the air;
after the aircraft (<NUM>) has flown, collecting the constituents (<NUM>) by either removing the collector (<NUM>) from the aircraft (<NUM>) or removing the constituents from the collector (<NUM>);
analyzing the constituents (<NUM>) to determine the amount of calcium-magnesium-aluminosilicate solids (CMAS) associated with the constituents;
inspecting the aircraft engine components for CMAS degradation; and
correlating the amount of CMAS collected in the environmental sampling system (<NUM>) to an amount of degradation in aircraft engine components.