Patent Description:
A liner of a combustion chamber of a gas turbine engine can include a plurality of effusion holes extending therethrough that facilitate the generation of a layer of cooling air that protects the liner from relatively high temperatures exhibited inside the combustion chamber. The effusion holes are sized and distributed on the liner so that the flow of cooling air through the liner provides the desired cooling. Such a liner can also include a thermal barrier coating (TBC) to further protect the liner from the high temperature environment inside the combustion chamber. During service, the TBC can eventually become damaged and its protective function can become compromised. Replacing the liner with a new liner can be costly. Improvement is desirable.

<CIT> describes a method of removing unwanted coating material from cooling passages of a turbine component that includes determining coordinates of the position and orientation of cooling passages at the surface of the turbine component and determining reference points in the region of the cooling passages. After coating of the turbine component, the reference points are measured once again and the thickness of the coating is calculated. In a basic processing program, the data for the position, passage orientation and coating thicknesses and also CAD data for the cooling passages are interlinked and a laser processing program is automatically adapted for each individual cooling passage. Using the laser processing program, a pulsed laser is guided over disk-shaped volume segments of the unwanted coating material and the material is removed in the process.

In one aspect, the invention describes a method of repairing a combustor liner of a gas turbine engine as claimed in claim <NUM>. In a further aspect, the invention describes a system for characterizing holes in a perforated part in preparation for repair as claimed in claim <NUM>.

Various embodiments of the invention are defined by the dependent claims.

Further details of these and other aspects of the subject matter of this application will be apparent from the dependent claims, as well as the detailed description included below and the drawings.

The following disclosure relates to methods and systems for repairing a combustor liner of a gas turbine engine or other coated parts that have holes extending therethrough. The methods and systems disclosed herein are useful when the combustion liner has deformed from a coating process during repair. Repairing the combustion liner may require characterizing one or more effusion (cooling) holes in the combustion liner before and after the coating process. In some situations, one or more effusion holes in the combustion liner may be at least partially obstructed (blocked) by the protective coating applied on the combustion liner and may need to be re-drilled.

The methods and systems described herein may facilitate the characterization of such effusion holes in the combustion liner that are at least partially obstructed by the coating to permit subsequent (e.g., laser) drilling. In some embodiments, the method disclosed herein can include removing a damaged coating on the combustion liner, applying a new coating on the combustion liner and also drilling through one or more at least partially blocked effusion holes. In some embodiments, the methods disclosed herein can reduce scrap material and repair costs by reusing the base material of the part instead of having to replace the part entirely.

The term "substantially" as used herein may be applied to modify any quantitative representation which could permissibly vary without resulting in a change in the basic function to which it is related.

<FIG> illustrates gas turbine engine <NUM> of a type preferably provided for use in subsonic flight, generally comprising in serial flow communication fan <NUM> through which ambient air is propelled, multistage compressor <NUM> for pressurizing the air, combustor <NUM> in which the compressed air is mixed with fuel and ignited for generating an annular stream of hot combustion gases, and turbine section <NUM> for extracting energy from the combustion gases. The methods disclosed herein can be used to repair part <NUM> (e.g., combustor liner) of engine <NUM> or other types of perforated components that can require a thermal barrier coating (TBC) or other type(s) of coati ng.

<FIG> is a flowchart of an exemplary method <NUM> of characterizing holes in a part in preparation for repair. It is understood that aspects of method <NUM> can be combined with other (e.g., repair) methods described herein. In various embodiments, method <NUM> includes:.

Aspects of method <NUM> are described in further detail below in reference to <FIG>.

<FIG> is a flow diagram illustrating an exemplary method <NUM> for repairing part <NUM> of gas turbine engine <NUM>. It is understood that aspects of method <NUM> can be combined with aspects of method <NUM> and other methods disclosed herein. In various embodiments, part <NUM> can be, for example, a combustor liner, a combustor shield, a blade or a vane ring of engine <NUM>. Part <NUM> can have an annular or a non-annular configuration. Part <NUM> may have a curved or substantially planar geometry. Part <NUM> may have a sheet form. Part <NUM> may contain one or more holes such as first hole 20A and second hole 20B (referred generically herein as "holes <NUM>") extending therethrough.

In some embodiments, where part <NUM> is a combustor liner for example, holes <NUM> can be effusion cooling holes through which some of the compressed air enters combustor <NUM> during operation of engine <NUM>. The individual sizes, orientations and distribution (e.g., spacing and pitch) of holes <NUM> through part <NUM> can be configured to provide a desired flow rate of air into combustor <NUM> and also protect combustor <NUM> from the elevated temperatures associated with the combustion process. Holes <NUM> can be (e.g., laser) drilled through part <NUM> at normal or oblique (i.e., non-normal) angles relative to respective surfaces of part <NUM> through which respective holes <NUM> extend. Holes <NUM> can extend linearly across the thickness of part <NUM>. During operation of the combustor liner, the air can flow through holes <NUM> and form a film cooling layer along first (e.g., inner) side 22A of part <NUM> via a process known as effusion cooling. Accordingly, the configuration of holes <NUM> can be selected (e.g., calibrated) based on air flow requirements to provide a desired cooling effect on part <NUM>. In some embodiments, part <NUM> can be initially manufactured according to the teachings of <CIT> entitled METHOD OF MAKING A PART AND RELATED SYSTEM, which is incorporated herein by reference.

Part <NUM> can be made from a suitable metallic material such as a nickel-based alloy for example selected based on the environmental conditions to which part <NUM> is exposed. In some embodiments, part <NUM> can be in the form of a relatively thin sheet formed to the desired geometry. Part <NUM> can comprise coating <NUM> bonded thereto for providing further protection against the elevated temperatures to which part <NUM> can be exposed.

Coating <NUM> can be applied and bonded to one side (e.g., first side 22A) of part <NUM> which is directly exposed to the hot gasses produced by the combustion process. For example, first side 22A of part <NUM> can be facing the combustion process during operation of engine <NUM>. Coating <NUM> may be a TBC. It is understood that aspects of this invention are applicable to parts <NUM> having other types of coatings as well. TBC can, for example, comprise a suitable MCrAlY material which can offer thermal and corrosion protection and where M denotes nickel, cobalt, iron or mixtures thereof; Cr denotes chromium; Al denotes aluminium; and Y denotes yttrium. TBC can comprise a ceramic layer applied on top of the MCrAlY layer to provide further thermal protection. An example of such ceramic coating material is yttria stabilised zirconia (YSZ) which can be applied on top of the MCrAlY layer. The MCrAlY and ceramic protective coatings can be applied on part <NUM> using a suitable deposition system <NUM>. The MCrAlY and ceramic protective coatings can be applied by physical vapour deposition (PVD), chemical vapour deposition (CVD) or plasma spraying means for example.

During service, part <NUM> can be subjected to cyclic exposure to relatively harsh environmental conditions (e.g., hot combustion gasses) and degradation of an existing coating on part <NUM> can occur over time. For example, portions of the existing coating can become cracked and/or some portions of the existing coating can become removed from part <NUM> and thereby expose the underlying metallic material of part <NUM>. Instead of having to replace part <NUM> entirely, the methods disclosed herein can be used to repair part <NUM> by reusing the base material without significantly altering the configuration of holes <NUM> and hence without significantly altering the (e.g., calibrated) air flow conditions across part <NUM>. An existing coating that has been cracked and/or damaged can be replaced by new coating <NUM>.

In various embodiments, method <NUM> can be used to clear one or more holes <NUM> that may have been at least partially obstructed by the application of coating <NUM> on part <NUM>.

Method <NUM> comprises receiving part <NUM> in a state where an existing coating on part <NUM> is damaged. Method <NUM> includes removing the existing coating on part <NUM>. The removal of the existing coating can comprise sand-blasting or grinding for example.

Method <NUM> includes acquiring first measured data <NUM> indicative of a geometry of part <NUM> with part <NUM> in an uncoated state. First measured data <NUM> may include a plurality of <NUM>-dimensional data points that represent various points on a surface of part <NUM> with part <NUM> in the uncoated state.

Method <NUM> includes using the first measured data to determine first location 38A and first orientation 40A of first hole 20A in part <NUM> (as shown in <FIG>) and first location 38B and first orientation 40B of second hole 20B in part <NUM> (as shown in <FIG>) with part <NUM> in the uncoated state. In some embodiments, determining first location 38A and first orientation 40A of first hole 20A and first location 38B and first orientation 40B of second hole 20B may include additionally using nominal data <NUM> indicative of a nominal geometry of part <NUM>. Nominal data <NUM> may be a digital representation (e.g., data points, lines, surfaces, solid models) such as computer aided design (CAD) model from which part <NUM> was initially manufactured.

Method <NUM> includes, after a coating process has applied coating <NUM> on part <NUM> and has optionally caused deformation of part <NUM>, acquiring second measured data <NUM> indicative of a geometry of part <NUM> in a coated state where first hole 20A is substantially unobstructed by coating <NUM> and second hole 20B is at least partially obstructed by coating <NUM>. Second measured data <NUM> may include a plurality of data points that represent various points on a surface of part <NUM> with part <NUM> in the coated state.

Method <NUM> includes using second measured data <NUM> to determine second location 82A and optionally second orientation 84A of first hole 20A in part <NUM> with part <NUM> in the coated state (as shown in <FIG>). In some embodiments, determining second location 82A and second orientation 84A of first hole 20A may include additionally using first measured data <NUM>.

Method <NUM> includes inferring second location 82B of second hole 20B (as shown in <FIG>) with part <NUM> in the coated state using: second location 82A first hole 20A; and a known spacing D<NUM> (as shown in <FIG>) between first hole 20A and second hole 20B determined from nominal data or from the first measured data <NUM> of part <NUM> in an uncoated state. Spacing D<NUM> (shown in <FIG>) may represent a distance and a direction between hole 20A and second hole 20B. Determining second orientation 84B of second hole 20B includes using first orientation 40B of second hole 20B. In some embodiments, determining second orientation 84B of second hole 20B may includes assigning first orientation 40B of second hole 20B as second orientation 84B of second hole 20B. Alternatively, second orientation 84B of second hole 20B may include an adjustment of first orientation 40B of second hole 20B based on a difference between first orientation 40A of first hole 20A and second orientation 84A of first hole 20A.

Method <NUM> includes (e.g., laser, mechanical) drilling through coating <NUM> at least partially obstructing second hole 20B using second location 82B and second orientation 84B of second hole 20B.

Even though aspects of the methods disclosed herein are described in relation to first hole 20A and second hole 20B for clarity, it is understood that the methods disclosed herein can be used with a plurality (e.g., <NUM>'s, <NUM>'s or <NUM>'s) of holes <NUM> that extend through part <NUM>. Aspects of methods <NUM> and <NUM> are further described below in reference to <FIG>.

<FIG> is a schematic illustration of an exemplary embodiment of system <NUM> for characterizing effusion holes <NUM> in part <NUM> and optionally also repair part <NUM> of gas turbine engine <NUM>. System <NUM> may include computer <NUM>, one or more measurement devices <NUM> (referred hereinafter in the singular), one or more user input devices <NUM> (e.g., keyboard, mouse) (referred hereinafter in the singular) and (e.g., laser or other type of) drilling system <NUM>. Computer <NUM> may be configured to receive input <NUM> (i.e. signals, data) from measurement device <NUM> and/or user input device <NUM> via one or more communication terminals/ports. Computer <NUM> includes one or more data processors <NUM> (referred hereinafter in the singular) and one or more computer-readable memories <NUM> (referred hereinafter in the singular) storing machine-readable instructions <NUM> executable by data processor <NUM> and configured to cause data processor <NUM> to generate output <NUM> (e.g. signals, data) for causing the execution of one or more steps of the methods described herein. Computer <NUM> may be configured to generate output <NUM> for controlling drilling system <NUM>. For example, output <NUM> may include a data set constructed by computer <NUM>. Output <NUM> may be stored in memory <NUM> or other non-transitory computer readable storage medium. Output <NUM> may include data indicative of the location and orientation of one or more at least partially obstructed effusion hole(s) <NUM>. Output <NUM> may include a digital representation of numerical values indicative of a characterization of one or more holes <NUM>. For example, output <NUM> may include three-dimensional positional coordinates (e.g., x, y, z) and a directional vector (e.g., i, j, k) associated with one or more holes <NUM>. In situations where part <NUM> is planar and holes <NUM> of interest all have the same orientation, two-dimensional positional coordinates (e.g., x, y) of hole(s) <NUM> may be sufficient and a directional vector may not be required. In some embodiments, output <NUM> may be a digital CAD model. In some embodiments, output <NUM> may include computer numerical control (CNC) commands or otherwise be usable for controlling the operation of drilling system <NUM>.

Data processor <NUM> may include any suitable device(s) configured to cause a series of steps to be performed by computer <NUM> so as to implement a computer-implemented process such that instructions <NUM>, when executed by computer <NUM> or other programmable apparatus, may cause the functions/acts specified in the methods described herein to be executed. Data processor <NUM> may include, for example, any type of general-purpose microprocessor or microcontroller, a digital signal processing (DSP) processor, an integrated circuit, a field programmable gate array (FPGA), a reconfigurable processor, other suitably programmed or programmable logic circuits, or any combination thereof.

Memory <NUM> may include any suitable machine-readable storage medium. Memory <NUM> may include non-transitory computer readable storage medium such as, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. Memory <NUM> may include a suitable combination of any type of computer memory that is located either internally or externally to computer <NUM>. Memory <NUM> may include any storage means (e.g. devices) suitable for retrievably storing machine-readable instructions <NUM> executable by data processor <NUM>.

Various aspects of the present invention may be embodied as systems, devices, methods and/or computer program products. Accordingly, aspects of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, aspects of the present invention may take the form of a computer program product embodied in one or more non-transitory computer readable medium(ia) (e.g., memory <NUM>) having computer readable program code (e.g., instructions <NUM>) embodied thereon. Computer program code for carrying out operations for aspects of the present invention in accordance with instructions <NUM> may be written in any combination of one or more programming languages. Such program code may be executed entirely or in part by computer <NUM> or other data processing device(s). Based on the present invention, one skilled in the relevant arts could readily write computer program code for implementing the methods described herein.

<FIG> schematically illustrates the acquisition of first measured data <NUM> using measurement device <NUM> of system <NUM> when part <NUM> is in an uncoated state. Measurement device <NUM> may be configured to <NUM>-dimensionally (3D) scan first side 22A of part <NUM> to obtain first measured data <NUM>. In some embodiments, measurement device <NUM> may be configured to only scan a portion of first side 22A that is proximate holes <NUM>. Although, measurement device <NUM> is depicted as scanning first side 22A of part <NUM>, it should be understood that measurement device <NUM> may also acquire first measured data <NUM> of part <NUM> by alternatively or additionally scanning second side 22B of part <NUM>.

First location 38A of first hole 20A may be indicative of a location of a central axis of first hole 20A on first side 22A of part <NUM> when part <NUM> is in the uncoated state. First location 38B of second hole 20B may be indicative of a location of a central axis of second hole 20B on first side 22A of part <NUM> when part <NUM> is in the uncoated state. As depicted, first location 38A of first hole 20A is spaced apart from first location 38B of second hole 20B by spacing D<NUM>. First orientation 40A of first hole 20A may be indicative of an orientation of the central axis of first hole 20A of part <NUM> when part <NUM> is in the uncoated state. First orientation 40B of second hole 20B may be indicative of an orientation of the central axis of second hole 20B of part <NUM> when part <NUM> is in the uncoated state. As depicted, the central axis of first hole 20A is oriented at angle αA relative to portion <NUM> of surface <NUM> of part <NUM>. As depicted, the central axis of second hole 20B is oriented at angle αB relative to portion <NUM> of surface <NUM> of part <NUM>. In some embodiments, first orientation 40A of first hole 20A may be substantially equal to first orientation 40B of second hole 20B. In this situation, angle αA may be substantially equal to angle αB. Although first hole 20A is shown as being directly adjacent to second hole 20B, it should be understood that first hole 20A does not have to be directly adjacent to second hole 20B.

Measurement device <NUM> may be controlled during scanning to obtain the required measurement readings (i.e. data points) for determining first location 38A and first orientation 40A of first hole 20A and first location 38B and first orientation 40B of second hole 20B. In some embodiments, measurement device <NUM> may be manually controlled by an operator. In some embodiments, measurement device <NUM> may be operatively controlled using computer <NUM> (not shown in <FIG>) or other system. Computer <NUM> may be configured to control a position and/or orientation of measurement device <NUM> via a suitable motion system. In some embodiments, measurement device <NUM> may be controlled by a combination of computer <NUM> and an operator.

As illustrated in <FIG>, an orientation of measurement device <NUM> can be adjusted during scanning to obtain first measured data <NUM>. As depicted, measurement device <NUM> is oriented to scan in first direction DIR<NUM>, second direction DIR<NUM>, third direction DIR<NUM> and fourth direction DIR<NUM> to acquire the measurement readings (i.e. data points) necessary to determine first location 38A and first orientation 40A of first hole 20A. In some cases, measurement device <NUM> may be incapable of acquiring measurement readings within undetectable (blind) region 42A. Measurement device <NUM> may be limited to scanning part <NUM> only on first side 22A of part <NUM> due to accessibility constraints thereby preventing the acquisition of measurement readings within undetectable region 42A. Part <NUM> may be oriented such that access is only provided to measurement device <NUM> on first side 22A of part <NUM>. As depicted, undetectable region 42A is a portion of first hole 20A that is distant from surface 25A of part <NUM>. In alternative embodiments, part <NUM> may be oriented such that measurement device <NUM> is only capable of scanning part <NUM> on second side 22B of part <NUM>.

First measured data <NUM> may be acquired using any suitable type of measurement device <NUM>. In some embodiments, measurement device <NUM> can comprise a non-contact measurement device. For example, measurement device <NUM> can comprise an optical (e.g., laser, blue light, white light) 3D scanner. The 3D scanner may be a portable handheld scanner that is easy to manipulate such as a HandySCAN AEROPACK™. In some embodiments, measurement device <NUM> can be configured for contact measurement and can comprise a suitable coordinate measurement machine (CMM). In some embodiments, a combination of contact and non-contact measuring techniques can be used with the methods disclosed herein.

<FIG> is a table showing first measured data <NUM>. First measured data <NUM> may include a plurality of data points defining x-axis, y-axis and z-axis coordinates of various points on a surface of part <NUM> with part <NUM> being in an uncoated state. First measured data <NUM> may be illustrated as a point cloud showing the various points in space as shown in <FIG> and <FIG>. In some embodiments, a subset of data points in first measured data <NUM> may be selected manually by an operator or may be determined automatically to define target bounding region <NUM> within first measured data <NUM> as graphically shown in <FIG>. Target bounding region <NUM> may define a region in first measured data <NUM> where a repair is expected to be performed. In some embodiments, target bounding region <NUM> may include first hole 20A and/or second hole 20B. For example, points <NUM>-<NUM> are illustrated as defining target bounding region <NUM>.

In some embodiments, target bounding region <NUM> may be determined using nominal data <NUM>. For example, computer <NUM> may be configured to use nominal location 43A of first hole 20A (as shown in <FIG>) and/or nominal location 43B of second hole 20B (as shown in <FIG>) obtained using nominal data <NUM> to determine target bounding region <NUM> in first measured data <NUM>. In some embodiments, nominal data <NUM> may be acquired by computer <NUM> from user input device <NUM>. In some embodiments, nominal data <NUM> may be stored in memory <NUM> of computer <NUM> or otherwise be accessible to computer <NUM>.

<FIG> is a flow diagram illustrating an exemplary method <NUM> for fitting first measured data <NUM> with nominal data <NUM>. It is understood that aspects of method <NUM> may be combined with aspects of other methods described herein. Method <NUM> may be included in method <NUM> and may occur after acquiring first measured data <NUM> and before identifying first location 38A and first orientation 40A of first hole 20A and first location 38B and first orientation 40B of second hole 20B. Aspects of method <NUM> may be performed with the assistance of suitable metrology software such as POLYWORKS®. Aspects of method <NUM> are described in reference to <FIG> below.

<FIG> is a graphical representation showing first measured data <NUM> and nominal data <NUM> before fitting first measured data <NUM> with nominal data <NUM>. As depicted, first measured data <NUM> is not aligned with nominal data <NUM>.

<FIG> is a graphical representation of first measured data <NUM> fitted to nominal data <NUM>. In some embodiments, method <NUM> may include performing an initial fitting of first measured data <NUM> to nominal data <NUM>. Fitting may entail performing a best-fit alignment of first measured data <NUM> to nominal data <NUM> according to known or other methods. As depicted, first measured data <NUM> may include target bounding region <NUM> (shown in broken lines). In some embodiments, a region defined by target bounding region <NUM> in first measured data <NUM> may not be accurately fitted to the corresponding region in nominal data <NUM> after the initial alignment. Part <NUM> may have deformed during service from exposure to harsh environmental conditions (e.g., hot combustion gasses). A geometry of part <NUM> after service (i.e. as illustrated in first measured data <NUM>) may be different than a nominal geometry of part <NUM> (i.e. as illustrated in nominal data <NUM>). In some embodiments, it may be desirable to have the region defined by target bounding region <NUM> in first measured data <NUM> accurately fitted to the corresponding region in nominal data <NUM> in order to accurately determine first location 38A and first orientation 40A of first hole 20A and first location 38B and first orientation 40B of second hole 20B.

<FIG> is a graphical representation of a region of first measured data <NUM> captured by target bounding region <NUM>. As depicted, first location 38A of first hole 20A in first measured data <NUM> is offset from nominal location 43A of first hole 20A in nominal data <NUM> by first positional deviation D<NUM>. In some embodiments, first positional deviation D<NUM> may be greater than a desired threshold T. Threshold T may define a maximum deviation between first location 38A and nominal location 43A allowable for ensuring that first location 38A and first orientation 40A of first hole 20A and first location 38B and first orientation 40B of second hole 20B can be determined sufficiently accurately.

Although, target bounding region <NUM> is depicted as having a rectangular profile, it is understood that target bounding region <NUM> may have a profile of a different shape. Although target bounding region <NUM> is depicted as being a region including multiple features (e.g. holes <NUM>), it is understood that target bounding region <NUM> may be a region that includes one or more features. In some embodiments, target bounding region <NUM> may be a region that includes only first hole 20A. In some embodiments, target bounding region <NUM> may be region that includes only second hole 20B. In some embodiments, target bounding region <NUM> may include first hole 20A and second hole 20B.

After the initial fitting, method <NUM> may include determining if a region defined by target bounding region <NUM> in first measured data <NUM> is fitted within an acceptable tolerance to the corresponding region in nominal data <NUM> to permit an accurate determination of first location 38A and first orientation 40A of first hole 20A.

In some embodiments, determining if the region defined by target bounding region <NUM> in first measured data <NUM> is fitted to the corresponding region in nominal data <NUM> to permit an accurate determination of first location 38A and first orientation 40A of first hole 20A may include computing first positional deviation D<NUM> between an estimated center of first hole 20A in first measured data <NUM> and an estimated center of first hole 20A in nominal data <NUM>. Determining the first positional deviation D<NUM> may require a user to manually select the centre of first hole 20A in first measured data <NUM> and manually select the centre of first hole 20A in nominal data <NUM> using a CAD or metrology software such as POLYWORKS®. Alternatively, a process of determining the first positional deviation D<NUM> may be automated or partially automated using macros or application programming interfaces (API) of suitable CAD or metrology software.

In a situation that first positional deviation D<NUM> is less than threshold T, it may be determined that the region defined by target bounding region <NUM> in first measured data <NUM> is adequately fitted to the corresponding region in nominal data <NUM>. In a situation where first positional deviation D<NUM> is greater than threshold T, method <NUM> may proceed to block <NUM> of method <NUM> to improve the quality of the best fit especially in cases where the deformation of part <NUM> from nominal geometric data <NUM> is significant. In some embodiments, the initial fitting may not be conducted and method <NUM> may begin at block <NUM> of method <NUM>.

Method <NUM> may include generating a copy of first measured data <NUM> (block <NUM>). Method <NUM> may include creating first proposed bounding region <NUM> within the copy of first measured data <NUM> (as shown in <FIG>) (block <NUM>). First proposed bounding region <NUM> may be set to capture a region in first measured data <NUM> which includes target bounding region <NUM>.

<FIG> is a graphical representation of the copy of first measured data <NUM>, first proposed bounding region <NUM>, second proposed bounding region <NUM> and target bounding region <NUM> (shown in broken lines). As illustrated in <FIG>, sides 55A and 55C of first proposed bounding region <NUM> are set to be at distance D<NUM> from temporary origin 55E and sides 55B and 55D are set to be at a distance D<NUM> from temporary origin 55E. As depicted, a location of temporary origin 55E is proximate target bounding region <NUM> and is offset from a location of an origin of a coordinate system used to locate the copy of first measured data <NUM>. A size of first proposed bounding region <NUM> and a location of temporary origin 55E may be automatically or manually chosen. In some cases, a size of first proposed bounding region <NUM> and a location of temporary origin 55E may be chosen based on a size of target bounding region <NUM> and/or a location of target bounding region.

Method <NUM> may include reducing the copy of first measured data <NUM> by removing one or more first data points from the copy of first measured data <NUM> that are outside of first proposed bounding region <NUM> (block <NUM>). The copy of first measured data <NUM> may be reduced to define only geometric coordinates of points within first proposed bounding region <NUM> after removing the one or more first data points.

Although first proposed bounding region <NUM> is illustrated as capturing a volume that is greater than a region of target bounding region <NUM>, it should be understood that first proposed bounding region <NUM> may be set to be equal to target bounding region <NUM>. In this situation, the copy of first measured data <NUM> may be reduced to define only geometric coordinates of points within target bounding region <NUM> after the one or more first data points are removed.

Method <NUM> may include determining a first transformation required to best fit the reduced copy of first measured data <NUM> to nominal data <NUM> (block <NUM>). Determining a first transformation may include creating a first transformation matrix using the reduced copy of first measured data <NUM>. The first transformation matrix may be indicative of a transformation (e.g. translation and/or rotation) to be applied, relative to a coordinate system, to best fit the reduced copy of the first measured data <NUM> to nominal data <NUM> to reduce positional deviation D<NUM>. For example a known or other best-fit algorithm may be applied to fit the reduced copy of the first measured data <NUM> to nominal data <NUM> and the resulting coordinate transformation matrix may be recorded. Method <NUM> may then include fitting (the non-reduced, original) first measured data <NUM> to nominal data <NUM> according to the recorded transformation matrix (block <NUM>).

In some embodiments, after fitting the original or reduced first measured data <NUM> to nominal data <NUM> according to the first transformation, method <NUM> may include determining if the region defined by target bounding region <NUM> in first measured data <NUM> is aligned to the corresponding region in nominal data <NUM> (block <NUM>) to an acceptable tolerance.

In some embodiments, determining if the fitting of the region defined by target bounding region <NUM> in first measured data <NUM> to the corresponding region in nominal data <NUM> is acceptable may include computing a second positional deviation (not shown) between an estimated center of first hole 20A in first measured data <NUM> and an estimated center of first hole 20A in nominal data <NUM> after fitting. Computing the second positional deviation may involve using a similar technique as explained above for computing first positional deviation D<NUM>.

In a situation where first proposed bounding region <NUM> is created to capture a volume that is the same as a volume of target bounding region <NUM>, it may be determined that the region defined by target bounding region <NUM> in first measured data <NUM> is aligned as close as possible to the corresponding region in nominal data <NUM>. In this situation, method <NUM> may proceed to determining first location 38A and first orientation 40A of first hole 20A (block <NUM>).

However, in a situation that first proposed bounding region <NUM> defines a volume that is greater than a volume of target bounding region <NUM>, method <NUM> may flow back to block <NUM> and a second proposed bounding region <NUM> may be created within the reduced copy of first measured data <NUM> that more closely narrows in on target bounding region <NUM> than first proposed bounding region <NUM>. In other words the reduced copy of first measured data <NUM> may be further reduced based on a smaller proposed bounding region and part of method <NUM> may be repeated iteratively until an acceptable best fit is obtained.

As depicted in <FIG>, sides 59A and 59C of second proposed bounding region <NUM> are set to be at a distance D<NUM> from temporary origin 59E and sides 59B and 59D are set to be at a distance D<NUM> from temporary origin 59E. As depicted, D<NUM> is less than D<NUM> and D<NUM> is less than D<NUM>. A volume captured by second proposed bounding region <NUM> may be less than a volume captured by first proposed bounding region <NUM>.

Although a first depth of first proposed bounding region <NUM> and a second depth of second proposed bounding region <NUM> are not depicted, it should be understood the second depth may be equal to or less than the first depth. Similarly, a target depth of target bounding region <NUM> may be equal or less than the first depth and the second depth.

Method <NUM> may be a form of bounding box regression and may include further reducing the reduced copy of first measured data <NUM> by removing one or more second data points from the reduced copy of first measured data <NUM> that are outside second proposed bounding region <NUM> (block <NUM>). The copy of first measured data <NUM> may be reduced to define only geometric coordinates of points within second proposed bounding region <NUM> after removing the one or more second data points.

Method <NUM> may include determining a second transformation required to best fit the twice (or more times) reduced copy of first measured data <NUM> to nominal data <NUM> (block <NUM>). Determining the second transformation may include creating a second transformation matrix using the twice reduced copy of first measured data <NUM>. The second transformation matrix may be indicative of a transformation (e.g. translation and/or rotation) to be applied, relative to a coordinate system, to best fit the twice reduced copy of the first measured data <NUM> to nominal data <NUM> to reduce positional deviation D<NUM>. For example, a known or other best-fit algorithm may be applied to fit the twice reduced copy of the first measured data <NUM> to nominal data <NUM> and the resulting coordinate transformation matrix may be recorded. Method <NUM> may then include fitting (the non-reduced, original) first measured data <NUM> to nominal data <NUM> according to the recorded transformation matrix (block <NUM>).

Method <NUM> may then flow back to block <NUM> of determining if the fitting of the region defined by target bounding region <NUM> in first measured data <NUM> to the corresponding region in nominal data <NUM> is acceptable.

In a situation that second proposed bounding region <NUM> is created to capture a volume that is the same as a volume of target bounding region <NUM>, it may be determined that the region defined by target bounding region <NUM> in first measured data <NUM> is aligned as close as possible to the corresponding region in nominal data <NUM>. In this situation, method <NUM> may proceed to determining first location 38A and first orientation 40A of first hole 20A (block <NUM>).

In some embodiments, determining if the region defined by target bounding region <NUM> in first measured data <NUM> is fitted to an acceptable degree to the corresponding region in nominal data <NUM> may include computing a third deviation between an estimated center of first hole 20A in first measured data <NUM> and an estimated center of first hole 20A in nominal data <NUM>. Computing the third positional deviation may involve using the technique explained above for computing first positional deviation D<NUM>.

In a situation where the second positional deviation is equal to the third positional deviation, it may be determined that target bounding region <NUM> in first measured data <NUM> is fitted as close as possible to the corresponding region in nominal data <NUM>. In this situation, method <NUM> may proceed to determining first location 38A and first orientation 40A of first hole 20A (block <NUM>).

In a situation where the second positional deviation is not equal to the third positional deviation, method <NUM> may flow back to block <NUM> and a new proposed bounding region (not shown) may be created that more closely narrows in on target bounding region <NUM> than second proposed bounding region <NUM>.

The process of creating a proposed bounding region in the copy of first measured data <NUM>, reducing the copy of first measured data <NUM> by removing one or more data points outside the proposed bounding region, determining a transformation required to best fit the reduced copy of first measured data <NUM> to the nominal data <NUM> and fitting the first measured data <NUM> to the nominal data <NUM> using the transformation may be repeated in an iterative manner until a first condition and/or a second condition are met. The first condition may occur when a proposed bounding region is created that has a volume that is the same as a volume of target bounding region <NUM>. The second condition may occur when a positional deviation computed between first hole 20A in first measured data <NUM> and first hole 20A in nominal data <NUM> after an nth fitting attempt is equal to a positional deviation computed between first hole 20A in first measured data <NUM> and first hole 20A in nominal data <NUM> after an nth-<NUM> fitting attempt. It should be understood that a new proposed bounding region may be created to have a volume that is less than any previous proposed bounding region(s) created and a volume of the new proposed bounding region may include a volume of target bounding region <NUM>.

If the second condition is met before the first condition, the proposed bounding region (not shown) created for the nth fitting attempt may have a volume that is greater than a volume of target bounding region <NUM>. This may be advantageous since the reduced copy of first measured data <NUM> used to create the nth transformation matrix for the nth fitting attempt may also contain data points outside target bounding region <NUM>.

The transformation of original (unreduced) first measured data <NUM> using transformation matrix determined using the above method may be advantageous because the complete first measured data <NUM> may include datum or other features that may be useful in the repair process for the purpose of establishing a coordinate system and/or locating part <NUM> on or relative to drilling system <NUM>.

Although method <NUM> involves creating a proposed bounding region in a copy of first measured data <NUM> and reducing the copy of first measured data <NUM> by removing one or more data points outside the proposed bounding region in the copy of first measured data <NUM>, it should be understood that method <NUM> may instead involve creating a proposed bounding region in a copy of nominal data <NUM> and reducing the copy of nominal data <NUM> by removing one or more data points outside the proposed bounding region in the copy of nominal data <NUM>. In this case, method <NUM> may involve determining a transformation required to best fit the reduced copy of nominal data <NUM> to first measured data <NUM> and fitting nominal data <NUM> to first measured data <NUM> using the transformation.

<FIG> is a flow diagram illustrating an exemplary method <NUM> for determining first location 38A and first orientation 40A of first hole 20A and first location 38B and first orientation 40B of second hole 20B using first measured data <NUM>. It is understood that aspects of method <NUM> may be combined with aspects of other methods described herein. Aspects of method <NUM> are explained below in reference to <FIG>.

<FIG> is a table showing exemplary first measured data <NUM> containing first data points <NUM> (illustrated as points <NUM>-<NUM>) and second data points <NUM> (illustrated as points <NUM>-<NUM>). Method <NUM> may include identifying first data points <NUM> and second data points <NUM> in first measured data <NUM> using nominal data <NUM>. First data points <NUM> may be the data points in first measured data <NUM> that are within a first threshold distance from nominal location 43A of first hole 20A. Second data points <NUM> may be the data points in first measured data <NUM> that are within a second threshold distance from nominal location 43B of second hole 20B. The first threshold distance may be equal or not equal to the second threshold distance.

Method <NUM> may include generating first plane representation <NUM> (as shown in <FIG>) in first measured data <NUM> from first data points <NUM> and generating second plane representation <NUM> (as shown in <FIG>) in first measured data <NUM> from second data points <NUM>. The plane representations may be defined using a point and a normal, three non-collinear points, a line fitted through the first data points <NUM> and a point not on that line, two intersecting lines fitted through the first data points <NUM>, or two parallel lines fitted through the first data points <NUM> for example.

<FIG> is a graphical representation of a portion of first measured data <NUM> fitted to a portion of nominal data <NUM>. First plane representation <NUM> may be generated using at least some of first data points <NUM>. First plane representation <NUM> may be a representation of an area on a surface of part <NUM> where first hole 20A is expected to be located. Second plane representation <NUM> may be generated using at least some of second data points <NUM>. Second plane representation <NUM> may be a representation of an area on a surface of part <NUM> where second hole 20B is expected to be located.

In some embodiments, the first threshold distance used to identify first data points <NUM> and the second threshold distance used to identify second data points <NUM> may both be equal to spacing D<NUM> divided by two. Spacing D<NUM> may be a distance between nominal location 43A of first hole 20A and nominal location 43B of second hole 20B. In this case, first plane representation <NUM> and second plane representation <NUM> may be circular and may capture an area of equal size. Although first plane representation <NUM> and second plane representation <NUM> are depicted as being flat/planar, it should be understood that in some embodiments, first plane representation <NUM> and second plane representation <NUM> may be curved to follow a curved surface of part <NUM>. In some embodiments, a shape of first plane representation <NUM> may be different than a shape of second plane representation <NUM>.

Method <NUM> may include generating first cylinder representation <NUM> (as shown in <FIG>) in first measured data <NUM> from first data points <NUM> and second cylinder representation <NUM> (as shown in <FIG>) in first measured data <NUM> from second data points <NUM>. Cylinder representations <NUM>, <NUM> may be created by fitting part of a cylindrical surface through some of data points <NUM>, <NUM>. The part of the cylindrical surface fitted through the data points <NUM>, <NUM> may then be used to derive a radius (or diameter), an orientation (e.g., i, j, k) and a location of the cylindrical representation <NUM> or <NUM>. Cylinder representations <NUM>, <NUM> may have a substantially circular cross-sectional profile.

<FIG> is a graphical representation of first measured data <NUM>, first plane representation <NUM>, second plane representation <NUM>, first cylinder representation <NUM> and second cylinder representation <NUM>. As depicted, first cylinder representation <NUM> intersects first plane representation <NUM> and second cylinder representation <NUM> intersects second plane representation <NUM>. First cylinder representation <NUM> may be created by using select data points within first data points <NUM> that represent points on a surface of part <NUM> that define first hole 20A. For example, the selected data points may be points on a lip of first hole 20A on surface <NUM> of part <NUM> and/or points on inner surfaces 25A of part <NUM> (as shown in <FIG>). Second cylinder representation <NUM> may be created by using select data points within second data points <NUM> that represent points on a surface of part <NUM> that define second hole 20B. For example, the selected data points may be points on a lip of second hole 20B on surface <NUM> of part <NUM> and/or points on inner surfaces 25B of part <NUM> (as shown in <FIG>).

Method <NUM> may include determining first location 38A and first orientation 40A of first hole 20A using first plane representation <NUM> and first cylinder representation <NUM>. In some embodiments, a central axis of first cylinder representation <NUM> may correspond to first orientation 40A of first hole 20A. In some embodiments, an intersection of first plane representation <NUM> and a central axis of first cylinder representation <NUM> may correspond to first location 38A of first hole 20A.

Similarly, method <NUM> may include determining first location 38B and first orientation 40B of second hole 20B using second plane representation <NUM> and second cylinder representation <NUM>. In some embodiments, a central axis of second cylinder representation <NUM> may correspond to first orientation 40B of second hole 20B. In some embodiments, an intersection of second plane representation <NUM> and a central axis of second cylinder representation <NUM> may correspond to first location 38B of second hole 20B.

After determining first location 38A and first orientation 40A of first hole 20A and first location 38B and first orientation 40B of second hole 20B, deposition system <NUM> may apply coating <NUM> on part <NUM>. The application of coating <NUM> on part <NUM> may cause one or more holes <NUM> to be at least partially obstructed by coating <NUM>, while leaving one or more other holes <NUM> unobstructed by coating <NUM>. The application of coating <NUM> on part <NUM> may cause second hole 20B to be at least partially obstructed by coating <NUM>, while first hole 20A may remain substantially unobstructed by coating <NUM>.

<FIG> schematically illustrates the acquisition of second measured data <NUM> using measurement device <NUM> of system <NUM> when part <NUM> is in a coated state. Measurement device <NUM> may be configured to 3D scan first side 22A of part <NUM> which is coated to obtain second measured data <NUM>.

Alternatively or in addition, measurement device <NUM> may be used to 3D scan a non-coated side (e.g. second side 22B) of part <NUM> to determine second measured data <NUM> (as shown in <FIG>). This may be a situation where first measured data <NUM> was acquired by 3D scanning second side 22B of part <NUM>. The illustrations in <FIG> and <FIG> are provided in schematic form and it is understood that coating material may penetrate and at least partially block second hole 20B. Depending on the size and orientation of second hole 20B, the thickness of part <NUM>, the coating material could potentially flow to the opposite side of part <NUM>. Accordingly, scanning of the uncoated second side 22B may also be used to identify at least partially blocked holes 20B. The presence of coating material inside second hole 20B may, in some situations, prevent the proper characterization of second hole 20B whether the scanning is performed from the coated or uncoated side of part <NUM>.

As depicted in <FIG>, second hole 20B is obstructed by coating <NUM>, while first hole 20A is substantially unobstructed by coating <NUM>. It is understood that measurement device <NUM> may operate in the same or a similar manner to acquire second measured data <NUM> as measurement device <NUM> operates to acquire first measured data <NUM>.

Second location 82A of first hole 20A may be indicative of a location of a central axis of first hole 20A on first side 22A of part <NUM> when part <NUM> is in the coated state. Second location 82B of second hole 20B may be indicative of a location of a central axis of second hole 20B on first side 22A of part <NUM> when part <NUM> is in the coated state. As depicted, second location 82A of first hole 20A is spaced apart from second location 82B of second hole 20B by spacing D<NUM>. Second orientation 84A of first hole 20A may be indicative of an orientation of the central axis of first hole 20A of part <NUM> when part <NUM> is in the coated state. Second orientation 84B of second hole 20B may be indicative of an orientation of the central axis of second hole 20B of part <NUM> when part <NUM> is in the coated state. As depicted, the central axis of first hole 20A is oriented at angle βA relative to portion <NUM> of surface <NUM> of part <NUM>. As depicted, the central axis of second hole 20B is oriented at angle βB relative to portion <NUM> of surface <NUM> of part <NUM>. In some embodiments, angle βA may be substantially equal to angle βB. A known thickness of coating <NUM> may be used to infer locations 82A, 82B under coating <NUM> based on the second measured data <NUM>.

In some cases, the application of coating <NUM> on part <NUM> may cause part <NUM> to deform due to the exposure to heat for example. Therefore, a geometry of the base material of part <NUM> in an uncoated state may differ from a geometry of the base material of part <NUM> in a coated state. First location 38A and first orientation 40A of first hole 20A may be different than second location 82A and second orientation 84A of first hole 20A, respectively. Similarly, first location 38B and first orientation 40B of second hole 20B may be different than second location 82B and second orientation 84B of second hole 20B, respectively. However, the relative spacing D<NUM> between first location 38A of first hole 20A and first location 38B of second hole 20B may be substantially equal to spacing D<NUM> between second location 82A of first hole 20A and second location 82B of second hole 20B.

Measurement device <NUM> may be automatically or manually controlled during the scanning process to obtain measurement readings (i.e. data points) necessary to determine second location 82A and second orientation 84A of first hole 20A. Depending on its type and/or orientation, measurement device <NUM> may be incapable of obtaining measurement readings in undetectable region <NUM> of first hole 20A. Second location 82A and second orientation 84A of first hole 20A may be determined using the data points acquired within the detectable region of second hole 20A. Measurement device <NUM> may be incapable of scanning second hole 20B due to the presence of coating <NUM> occluding second hole 20B.

In some embodiments, second measured data <NUM> may be fitted to first measured data <NUM>. In some situations, a geometry of part <NUM> in the uncoated state may be different than a geometry of part <NUM> in the coated state. In these situations, second measured data <NUM> may not accurately fit to first measured data <NUM> to permit an accurate determination of second location 82A and second orientation 84A of first hole 20A after an initial fitting. A fitting technique according to method <NUM> may be employed to fit a region defined by a second target bounding region (not shown) in second measured data <NUM> with the corresponding region in first measured data <NUM>.

<FIG> is a flow diagram illustrating an exemplary method <NUM> for determining second location 82A and second orientation 84A of first hole 20A and second location 82B and second orientation 84B of second hole 20B. Some of the techniques described in relation to method <NUM> above may be used in method <NUM>. It is understood that aspects of method <NUM> may be combined with aspects of other methods described herein. Aspects of method <NUM> are explained in reference to <FIG> and <FIG>.

<FIG> is a table showing second measured data <NUM> containing first data points <NUM> (illustrated as points <NUM>-<NUM>) and second data points <NUM> (illustrated as points <NUM>-<NUM>). Method <NUM> may include identifying first data points <NUM> and second data points <NUM> in second measured data <NUM> using first measured data <NUM>. First data points <NUM> may be the data points in second measured data <NUM> that are within a first threshold distance from first location 38A of first hole 20A and second data points <NUM> may be the data points in second measured data <NUM> that are within a second threshold distance from first location 38B of second hole 20B (block <NUM>). In some embodiments, the first threshold distance may be equal or not equal to the second threshold distance.

Method <NUM> may include using first data points <NUM> to determine that first hole 20A is substantially unobstructed by coating <NUM> (block <NUM>). Method <NUM> may include generating first plane representation <NUM> (as shown in <FIG>) in second measured data <NUM> on a surface of part <NUM> from first data points <NUM>. First plane representation <NUM> may be defined by at least some of first data points <NUM>. First plane representation <NUM> may be a representation of an area on a surface of part <NUM> where first hole 20A is expected to be located. Method <NUM> may include generating first cylinder representation <NUM> (as shown in <FIG>) in second measured data <NUM> from first data points <NUM>. First cylinder representation <NUM> may be created by using data points within first data points <NUM> that represent points on a surface of part <NUM> that define first hole 20A. For example, the selected data points may be representative of points on a lip of first hole 20A on surface <NUM> of part <NUM> and/or points on inner surfaces 89A of part <NUM> (as shown in <FIG>).

<FIG> is a graphical representation of a portion of second measured data <NUM>, first plane representation <NUM> and first cylinder representation <NUM>. As depicted, first cylinder representation <NUM> may intersect first plane representation <NUM>.

Method <NUM> may include determining second location 82A and second orientation 84A of first hole 20A using first data points <NUM> (block <NUM>). Specifically, method <NUM> may include determining second location 82A and second orientation 84A of first hole 20A using first plane representation <NUM> and first cylinder representation <NUM>. In some embodiments, a central axis of first cylinder representation <NUM> may correspond to second orientation 84A of first hole 20A. In some embodiments, an intersection of first plane representation <NUM> and the central axis of first cylinder representation <NUM> may correspond to second location 82A of first hole 20A.

Method <NUM> may include using the second data points <NUM> to determine that second hole 20B is at least partially obstructed by coating <NUM> (block <NUM>). Method <NUM> may include generating a second plane representation (not shown) in second measured data <NUM> on a surface of part <NUM> from second data points <NUM>. However, since second hole 20B is at least partially obstructed by coating <NUM>, it may not be possible to adequately generate a second cylinder representation in second measured data <NUM> from second data points <NUM> due to the presence of coating material inside second hole 20A. In this case, a plane representation and a cylinder representation cannot be used to determine second location 82B and second orientation 84B of second hole 20B.

Instead, method <NUM> may include inferring second location 82B of second hole 20B using second location 82A of first hole 20A (block <NUM>). Inferring second location 82B of second hole 20B may include using known spacing D<NUM> between first location 38A of first hole 20A and first location 38B of second hole 20B. Spacing D<NUM> between first location 38A of first hole 20A and first location 38B of second hole 20B may be may be substantially unaffected by the coating process. In some embodiments, second location 82B of second hole 20B may be determined using equation <NUM> shown below: <MAT>.

In equation <NUM>, XB2, YB2 and ZB2 may be the x-axis coordinate, y-axis coordinate and z-axis coordinate, respectively, of second location 82B of second hole 20B. XA2, YA2 and ZA2 may be the x-axis coordinate, y-axis coordinate and z-axis coordinate, respectively, of second location 82A of first hole 20A. XB1, YB1 and ZB1 may be the x-axis coordinate, y-axis coordinate and z-axis coordinate, respectively, of first location 38B of second hole 20B. XA1, YA1 and ZA1 may be the x-axis coordinate, y-axis coordinate and z-axis coordinate, respectively, of first location 38A of first hole 20A.

In some embodiments, determining second orientation 84B of second hole 20B may includes assigning first orientation 40B of second hole 20B as second orientation 84B of second hole 20B. Alternatively, second orientation 84B of second hole 20B may include an adjustment of first orientation 40B of second hole 20B based on a difference between first orientation 40A of first hole 20A and second orientation 84A of first hole 20A. In a situation where angle αB of second hole 20B is determined to be substantially equal to angle αA of first hole 20A, it may be assumed that second orientation 84B of second hole 20B is equal to second orientation 84A of first hole 20B.

<FIG> schematically illustrates drilling through coating <NUM> at least partially obstructing second hole 20B of part <NUM> using drilling system <NUM> of system <NUM>. Drilling through coating <NUM> at least partially obstructing second hole 20B using second location 82B and second orientation 84B of the second hole 20B. Using second location 82B and second orientation 84B of second hole 20B, suitable instructions can be generated to control drilling system <NUM> during the drilling of obstructed second hole 20B. In some embodiments, such instructions can comprise computer numerical control (CNC) commands for controlling the positioning of drilling system <NUM> for the re-drilling operation and other instructions for controlling other parameters of drilling system <NUM>. Such instructions (e.g., output <NUM> shown in <FIG>) can be generated by computer <NUM> configured to implement a suitable computer-aided-design/computer-aided-manufacturing (CAD/CAM) system for example.

<FIG> schematically illustrates the acquisition of second measured data <NUM> using measurement device <NUM> of system <NUM> with part <NUM> being in a coated state and containing repair patch <NUM> (shown in broken lines). Repair patch <NUM> may be added to part <NUM> to replace a damaged portion of a base metal of part <NUM>. Repair patch <NUM> may be added before or after acquiring first measured data <NUM> of part <NUM> and before applying coating <NUM> on part <NUM>. Repair patch <NUM> may replace a portion of part <NUM> where second hole 20B was previously defined. In this situation, drilling system <NUM> may be used to drill through coating <NUM> and through repair patch <NUM> to form second hole 20B in repair patch <NUM>. Second location 82B and second orientation 84B of second hole 20B may be inferred using second location 82A and second orientation 84A of first hole 20A and first measured data <NUM>. Specifically, second location 82B and second orientation 84B of second hole 20B may be inferred using a similar technique as the technique explained above in method <NUM>.

Claim 1:
A method of repairing a combustor liner (<NUM>) of a gas turbine engine (<NUM>), the method comprising:
removing an existing coating material from the combustor liner (<NUM>);
acquiring first measured data (<NUM>) indicative of a geometry of the combustor liner (<NUM>) in an uncoated state;
using the first measured data (<NUM>), determining:
a first location (38A) and a first orientation (40A) of a first hole (20A) in the combustor liner (<NUM>) with the combustor liner (<NUM>) in the uncoated state; and
a first location (38B) and a first orientation (40B) of a second hole (20B) in the combustor liner (<NUM>) with the combustor liner (<NUM>) in the uncoated state;
applying a new coating material on the combustor liner (<NUM>) so that the first hole (20A) is substantially unobstructed by the new coating material and the second hole (20B) is at least partially obstructed by the new coating material;
acquiring second measured data (<NUM>) indicative of a geometry of the combustor liner (<NUM>) in a coated state;
using the second measured data (<NUM>), determining a second location of the first hole (20A) with the combustor liner (<NUM>) in the coated state;
inferring a second location (82A) of the second hole (20B) with the combustor liner (<NUM>) in the coated state using:
the second location (82A) of the first hole (20A); and
a spacing between the first location (38A) of the first hole (20A) and the first location (38B) of the second hole (20B);
determining a second orientation (84B) of the second hole (20B) with the combustor liner (<NUM>) in the coated state based on the first orientation (40B) of the second hole (20B); and
drilling through the new coating material at least partially obstructing the second hole (20B) using the second location (82B) and the second orientation (84B) of the second hole (20B).