Patent Publication Number: US-11655052-B2

Title: Method and apparatus for locating and forming fastener holes in a replacement tip section of a rotor blade

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 16/100,971, filed Aug. 10, 2018, the contents of which are incorporated herein in their entirety by reference. 
    
    
     BACKGROUND 
     Exemplary embodiments of the invention relate to rotary-wing aircraft and, more particularly, to a system and method for machining features in new components of a rotor blade that match the existing features already present in an existing portion of the rotor blade of a rotary-wing aircraft. 
     Rotary wing aircraft include a plurality of main rotor blades coupled to a central hub. The rotor blades include aerodynamic surfaces that, when rotated, create lift. The configuration of the main rotor blades, particularly the tip end thereof, is selected to enhance rotor blade performance, for example to increase the hover and lift capabilities of the rotary-wing aircraft. Rotor blades are subjected to high stresses and strains resulting from aerodynamic forces developed during operation. 
     Typically, only a very end portion of a main rotor blade tip is designed to be replaceable since the tip portion is most susceptible to damage caused by erosion and solid object strikes. The replaceable portion is typically the outermost straight section and is limited by the strength of the attachment joint. Upon removal of the tip portion of the rotor blade, several machined features remain within the spar of the rotor blade. These features need to be re-established in the replacement tip section that is attached to the spar in order to retain the design intent and structure integrity of the blade assembly. Location of these features in the replacement tip section is complex and time consuming. 
     BRIEF DESCRIPTION 
     According to an embodiment, a system for regenerating fastener holes in a replacement tip section of a rotor blade includes a first fixture, a second fixture, and a third fixture positionable adjacent a tip section of the rotor blade. The first fixture is used to verify a position of an opening formed in the spar. The second fixture includes a removable bushing having a drillable opening. The drillable opening is aligned with the at least one opening formed in the spar and defines at least one hole to be formed in the replacement tip section. The third fixture includes a countersink opening. The countersink opening is aligned with the at least one hole to be formed in the replacement tip section and the at least one opening formed in the spar to define a countersink feature to be formed in the at least one hole. 
     In addition to one or more of the features described above, or as an alternative, in further embodiments each of the first fixture, the second fixture, and the third fixture is mountable at a same location relative to the rotor blade. 
     In addition to one or more of the features described above, or as an alternative, in further embodiments each of the first fixture, the second fixture, and the third fixture is coupled to the rotor blade via at least one weight cup opening. 
     In addition to one or more of the features described above, or as an alternative, in further embodiments the check opening, the drillable opening, and the countersink opening are substantially aligned relative to the rotor blade. 
     In addition to one or more of the features described above, or as an alternative, in further embodiments comprising at least one index pin and nut for mounting the first fixture to the tip section and a check pin receivable within at least one of the check opening, the opening formed in the tip section, and the opening formed in a spar of the rotor blade. 
     In addition to one or more of the features described above, or as an alternative, in further embodiments the opening formed in the tip section is in a correct position if one the check pin is receivable within the check opening, the opening formed in the tip section, and the opening formed in the spar. 
     In addition to one or more of the features described above, or as an alternative, in further embodiments comprising at least one index pin and nut for mounting the second fixture to the replacement tip section. 
     In addition to one or more of the features described above, or as an alternative, in further embodiments multiple removable bushings are associated with the opening to be formed in the replacement tip section. 
     In addition to one or more of the features described above, or as an alternative, in further embodiments the multiple removable bushings include three sequentially replaceable removable bushings, each of the three removable bushings defining an opening having a different diameter. 
     In addition to one or more of the features described above, or as an alternative, in further embodiments a drill is used with at least one of the multiple removable bushings and a ream is used with another of the multiple removable bushings to form the opening to be formed in the replacement tip section. 
     In addition to one or more of the features described above, or as an alternative, in further embodiments comprising at least one index pin and nut for mounting the third fixture to the replacement tip rotor section. 
     In addition to one or more of the features described above, or as an alternative, in further embodiments the at least one index pin has a flange such that the at least one index pin overlaps the countersink opening. 
     In addition to one or more of the features described above, or as an alternative, in further embodiments comprising another countersink opening formed in the third fixture and at least one secondary index pin insertable into the another countersink openings. 
     In addition to one or more of the features described above, or as an alternative, in further embodiments the at least one index pin is removed when the at least secondary one index pin is connected to the third fixture. 
     According to an embodiment, a method of forming fastener holes in a replacement tip section of a rotor blade includes identifying a datum of the replacement tip section, forming a hole in the replacement tip section using a first fixture mounted to the rotor blade, the first fixture being mounted at a position about the replacement tip section based on the datum, and countersinking the hole in the replacement tip section using a second fixture mounted to the rotor blade, the second fixture being mounted at a position about the replacement tip section based on the datum. 
     In addition to one or more of the features described above, or as an alternative, in further embodiments the second fixture is removably mounted to the rotor blade at a same position as the first fixture. 
     In addition to one or more of the features described above, or as an alternative, in further embodiments forming a hole into the replacement tip section of the rotor blade further comprises forming an opening via a first removable bushing installed into the fastener drill fixture, increasing a diameter of the opening via a second removable bushing installed into the fastener drill fixture, and further increasing a diameter of the opening via a third removable bushing installed into the fastener drill fixture. 
     In addition to one or more of the features described above, or as an alternative, in further embodiments increasing the diameter is performed via one of a drilling and reaming operation. 
     In addition to one or more of the features described above, or as an alternative, in further embodiments comprising: verifying a position of an opening formed in a spar of the rotor blade, removing a tip section of the rotor blade, and affixing the replacement tip section to the rotor blade. 
     In addition to one or more of the features described above, or as an alternative, in further embodiments comprising forming the datum of the replacement tip section. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: 
         FIG.  1    is a perspective view of an example of a rotary wing aircraft; 
         FIG.  2    is a perspective view of an example of a rotor blade of a rotary wing aircraft; 
         FIG.  3    is a perspective view of a tip section of a rotor blade assembly with a fastener tool check fixture affixed thereto according to an embodiment; 
         FIG.  4 A  is a perspective view of the fastener tool check fixture mounted to the rotor blade absent the check pins according to an embodiment; 
         FIG.  4 B  is a perspective view of the fastener tool check fixture mounted to the rotor blade with the check pins installed according to an embodiment; 
         FIGS.  5 A and  5 B  are perspective views of a second plate of the fastener tool check fixture affixed to a surface the rotor blade according to an embodiment; 
         FIG.  6    is a perspective view of a holding fixture according to an embodiment; 
         FIG.  7    is a perspective view of a first assembly of the holding fixture according to an embodiment; 
         FIG.  8    is a perspective view of a second assembly of the holding fixture according to an embodiment; 
         FIG.  9    is a detailed view of the second assembly of  FIG.  8    according to an embodiment; 
         FIG.  10 A  is a perspective view of a first plate of a fastener drill fixture affixed to a surface the rotor blade according to an embodiment; 
         FIG.  10 B  is a perspective view of a second plate of a fastener drill fixture affixed to a surface the rotor blade according to an embodiment; 
         FIG.  11    is a perspective view of a fastener countersink alignment fixture according to an embodiment; 
         FIG.  12 A  is a perspective view of a first plate of a fastener countersink alignment fixture affixed to a surface the rotor blade according to an embodiment; 
         FIG.  12 B  is a perspective view of a second plate of a fastener countersink alignment fixture affixed to a surface the rotor blade according to an embodiment; 
         FIG.  13    is a cross-sectional view of a microstop having a countersink cutter according to an embodiment; and 
         FIG.  14    is a perspective view of a second plate of a fastener countersink alignment fixture affixed to a surface the rotor blade according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. 
       FIG.  1    schematically illustrates an example of a rotary wing aircraft  10  having a main rotor assembly  12 . The aircraft  10  includes an airframe  14  having an extending tail  16  which mounts a tail rotor system  18 , such as an anti-torque system, a translational thrust system, a pusher propeller, a rotor propulsion system, and the like. The main rotor assembly  12  includes a plurality of rotor blade assemblies  22  mounted to a rotor hub  20  assembly. The main rotor assembly  12  is driven about an axis of rotation A through a main gearbox (illustrated schematically at T) by one or more engines E. Although a particular helicopter configuration is illustrated and described in the disclosed embodiment, other configurations and/or machines, such as high speed compound rotary wing aircrafts with supplemental translational thrust systems, dual contra-rotating, coaxial rotor system aircrafts, tilt-rotors and tilt-wing aircrafts, vertical takeoff and lift rotary wing aircrafts, and fixed wing aircrafts, will also benefit from embodiments of the disclosure. 
     Referring to  FIG.  2   , each rotor blade assembly  20  of the rotor assembly  12  generally includes a root section  22 , an intermediate section  24  and a tip section  26 . A blade cuff  23  is typically mounted at the inboard end  25  of the root section of the blade  20 . Each rotor blade section  22 ,  24 ,  26  may define particular airfoil geometries to tailor the rotor blade aerodynamics to the velocity increase along the rotor blade span. As illustrated, the rotor blade tip section  26  may include an anhedral form (not shown); however, any angled or non-angled forms such as cathedral, gull, bent, and other non-straight forms are within the scope of the present disclosure. The anhedral form (not shown) as defined herein may include a rotor blade tip section  26  which extends at least partially out of a plane defined by the intermediate section  24 . 
     The rotor blade sections  22 ,  24 ,  26  define a span R of the main rotor blade assembly  20  between the axis of rotation A and a distal end  28  of the blade  20  such that any radial station may be expressed as a percentage in terms of a blade radius x/R. The rotor blade assembly  20  defines a longitudinal feathering axis P between a leading edge  32  and a trailing edge  34 . 
     With reference now to  FIGS.  3 - 5   , a fixture or tool  40  is applied to the existing tip section  26  of the rotor blade assembly  20  to confirm whether the fastener holes (not shown) formed in the rotor blade assembly  20  are arranged at a desired position. As shown, the tool  40 , also referred to herein as a “fastener check fixture,” includes a first plate  42  positionable adjacent a first side or lower skin  44  of the rotor blade assembly  20 , and a second plate  46  positionable adjacent a second, opposite side, i.e. the upper skin  48  of the rotor blade assembly  20 . Each of the first plate  42  and second plate  46  includes a plurality of guide holes  50  within which various sized alignment pins are received. In an embodiment, the first and second plate  42 ,  46  include holes  50   a  sized for receiving indexing pins  52 , holes  50   b  sized for receiving check pins  54 , and holes  50   c  sized receiving thumb screws  56 . Further, the first and second plate  42 ,  46  may include large openings  58  that do not receive a pin, but rather reduce the surface area, and therefore the weight of the plates  42 ,  46 . Although the first and second plates  42 ,  46  are shown as being substantially identical, in other embodiments, the first and second plates  42 ,  46  may vary depending on the configuration of the rotor blade  20 . 
     To use the fastener check fixture, first and second indexing pins  52  are installed into corresponding openings  50   a  in the first plate  42 . The first plate  42  is then positioned in contact with the tip skin  44  of the blade assembly  20 , such as the lower tip skin of the blade assembly  20  for example, and the first and second indexing pins  52  are received within corresponding weight cup holes (not shown) formed in the blade assembly  20 . Similarly, the second plate  46  is mounted in contact with the opposite tip skin  48  of the blade assembly  20 , such as the upper tip skin for example. The second plate  46  is positioned such that the first and second indexing pins  52 , extending through the upper tip skin  48  of the blade assembly  20 , are received within corresponding openings  50   a  formed in the second plate  46 . A first and second knurl nut  60  are affixed to the first and second indexing pins  52 , respectively, to restrict movement of the first and second indexing pins  52  relative to the rotor blade assembly  20 . 
     A plurality of first thumb screws  56   a  and a plurality of second thumb screws  56   b , for example positionable near the corners of the first and second plate  42 ,  46 , respectively, are then threaded into engagement with the skins  44 ,  48  of the blade assembly  20  to stabilize the first and second plates  42 ,  46  relative to the blade  20 . Once the first and second plates  42 ,  46  are coupled to the rotor blade assembly  20 , a plurality of check pins  54  are inserted into a plurality of check pin openings  50   b  formed in one of the first plate  42  and the second plate  46  and a plurality of corresponding weight cup openings (not shown) formed in the skins  44 ,  48  of the blade assembly  20 . Check pins  54  that are not able to engage with an opening formed in the blade assembly  20  are identified. After each of the check pins  54  is inserted, the fixture  40  may be removed from the blade assembly  20  in a reverse order. While this fixture  40  is attached to the blade assembly  20 , the weight cup holes of the blade assembly  20  are re-drilled to establish indexing locations for downstream operations. 
     After verifying that the check pin openings  50   b  formed in the existing blade assembly  20  are in alignment with a desired position, the existing tip section  26  of the rotor blade assembly  20  is removed and a new tip section  26  is bonded to the remainder of the blade assembly  20 . With the new tip section  26  attached thereto, the blade assembly  20  is installed into a holding fixture  62  where weight cup openings are formed in the skins  44 ,  48  of the new tip section  26 . Further, within the holding fixture  62 , corresponding check pin openings and index openings are also formed in the skins  44 ,  48  of the blade assembly  20  via a drilling operation. 
     An example of the holding fixture  62  is illustrated in more detail in  FIGS.  6 - 9   . The holding fixture  62  includes a first assembly  64  for supporting an inboard end of the rotor blade assembly  20  and a second assembly  66  for supporting a portion of the rotor blade assembly  20  between the intermediate section  24  and the tip section  26 . The first assembly  64 , best shown in  FIG.  7   , includes a table  68  having a generally planar upper surface  70 . In an embodiment, the table  68  is movable vertically, i.e. up and down, such that the height of the table is adjustable. Alternatively, or in addition, the table  68  may be supported on w plurality of wheels such that the table may be rolled along a floor. 
     In an embodiment, an upper surface  70  of the table  68  includes a plurality of ball bearings  71 , and a contoured support  72  is resting on the upper surface  70  of the movable table  68 , and specifically on the ball bearings  71 . As a result, the contoured support is movable with the blade assembly  20  relative to the table  68 , such as during a machining operation for example. A lip  76  may be located at an edge of the upper surface  70  to restrict movement of the contoured support  72  from the upper surface  70 . In an embodiment, the shape of the surface  74  of the contoured support  72  corresponds to an adjacent surface of the rotor blade  20 . A lip  76  extends from an edge of the support  72  such that a portion of the blade assembly  20  may be rested on the surface  74  of the contoured support  72  and movement of the blade assembly  20  relative to the contoured support  72  and the table  68  is restricted by the lip  76 . 
     The second assembly  66  includes a base plate  78  adapted to mount, such as with one or more fasteners (not shown) to a corresponding surface  80  of a milling machine (not shown). When the base plate  78  is coupled to the milling machine, an upper surface  82  of the base plate  78  may, but need not be substantially flush with the upper surface  70  of the table  68  such that the blade  20  has a generally horizontal configuration. 
     One or more mounting mechanisms  84  may be used to mount or affix the rotor blade assembly  20  to the upper surface  82  of the base plate  78 . In an embodiment, a mounting mechanism  84  is used to affix a first end  86  of the rotor blade assembly  20 . In an embodiment, the mounting mechanism  84  includes a clamp having a vertically stacked first support plate  88  and second support plate  90 . The first support plate  88  and the second support plate  90  may be detachably coupled to one another, such as with one or more fasteners  92  for example. Alternatively, the first support plate  88  and the second support plate  90  may be pivotally coupled adjacent a first end such that the second support plate  90  is movable relative to the first support plate  88  between an open position and a closed position. The inner surface of the first and second support plates  88 ,  90  is contoured to match an adjacent surface of the intermediate section  24  of the rotor blade assembly  20 . As a result, when the second support plate  90  is substantially aligned with the first support plate  88  to define a chamber  94  within which a portion of the rotor blade  20  is received (see  FIG.  8   ), the clamp  84  applies a pressure to the surface of the rotor blade assembly  20  to prevent movement thereof relative to the base plate  78 . 
     Alternatively, or in addition, another mounting mechanism  84  may be used to secure the tip end  26  of the rotor blade assembly  20  to the base plate  78 . In the illustrated, non-limiting embodiment, the mounting mechanism  84  is a contoured support  96 . The support  96  has a contoured surface  99  complementary to the portion of the rotor blade assembly  20  configured to contact the support  96 . One or more pins  100  may be used to affix the tip section  26  of the blade assembly  20  in position relative to the support  96 . In an embodiment, the one or more pins  100  define a reference datum for determining a general location of the existing weight cup holes, from which a machinist can partially open up the cavity to locate the weight cup holes. Further, the support  96  may include one or more clamps  102  adjustable relative to the exposed surface of the rotor blade assembly  20 . In an embodiment, the clamps  102  have inwardly extending arms such that the position of the clamp  102  is adjusted to apply a force to the exposed surface of the rotor blade assembly  20 . Once the rotor blade assembly  20  is installed within the holding fixture  62 , the rotor blade  20  may be machined in accordance with a set of instructions. 
     With reference now to  FIGS.  10 A and  10 B , a fastener drill fixture  110  is used to identify the location of the fastener holes in the surface of the new tip section  26  of the rotor blade  20 . In an embodiment, the fastener drill fixture  110  is operable to identify the location of the fasteners holes, within an allowable tolerance. As shown, the fastener drill fixture  110  includes a first plate  112  positionable adjacent a first skin  44  of the rotor blade assembly  20 , and a second plate  114  positionable adjacent a second, opposite tip skin  48  of the rotor blade assembly  20 . Each of the first plate  112  and second plate  114  includes a plurality of guide holes  116  within which various sized alignment pins are received. In an embodiment, the first and second plate  112 ,  114  include holes  116   a  sized for receiving indexing pins  118 , holes  116   b  having a plurality of removable bushings  120  disposed therein to support a stepped drilling operation and/or a check pin  121 , and holes  116   c  sized receiving thumb screws  122 . Each of the removable bushings  120  includes a central hole  124 . Further, the first and second plate  112 ,  114  may be elongated such that an end of the first plate  112  is configured to contact, and in some embodiments, couple to an end of the second plate  114 , as shown in the FIGS. The first and second plates  112 ,  114  of the fastener drill fixture  110  may be substantially identical, or alternatively, may vary depending on the configuration of the rotor blade  20 . 
     To use the fastener drill fixture  110 , first and second indexing pins  118  are installed into corresponding openings  116   a  formed in the first plate  112 . The first plate  112  is then positioned in contact with a first tip skin  44  of the blade assembly  20 , such as a lower tip skin for example, and the first and second indexing pin  118  are received within corresponding weight cup holes (not shown) formed in the blade assembly  20 . Similar to the fastener check fixture  40 , the second plate  114  is mounted in contact with an opposite tip skin of the blade assembly  20 , such as the upper tip skin  48  for example. The second plate  114  is positioned such that the first and second indexing pins  118 , extending through the upper tip skin  48  are received within corresponding openings  116   a  formed in the second plate  114 . A first and second knurl nut  126  are coupled to the first and second indexing pin  118 , respectively, to restrict movement of the first and second pins  118  relative to the rotor blade assembly  20 . A plurality of thumb screws  122  disposed about the first plate  112  and the second plate  114  are then threaded into engagement with a surface of the blade assembly  20  to stabilize the first and second plates  112 ,  114  relative to the blade  20 . 
     Once the first and second plates  112 ,  114  are coupled to the rotor blade assembly  20 , holes are formed into the tip skins  44 ,  48  via the central holes  124  formed in the removable bushings  120 . Upon formation of the initial holes, the removable bushings  120  are then replaced with a second set of bushings  120  defining another central hole  124  having a larger diameter than the central hole  124  of the first set of bushings  120 . The initial holes are then enlarged by passing a drill through the holes  124  of the second set of bushings  120 . After this second drilling step, a third set of removable bushings  120  replaces the second set of removable bushings  120 . In an embodiment, the third set of removable bushings  120  define central holes  124  generally equal in diameter to the pin  121  to be received within each hole. In an embodiment, the holes defined by the third set of removable bushings  120  are greater in diameter than the holes defined by the second set of removable bushings  120 . A reaming operation is used to form the hole defined by each third removable bushing  120  to enlarge the hole formed in the skin of the tip section  26 . Once the drilling and reaming of each of the holes is complete, a final check pin  121  may be installed into each of the plurality of formed holes. This same process is repeated for the bushings  120  of both the first plate  112  and the second plate  114 . Once the plurality of holes is formed in both the upper and lower tip skins  44 ,  48  of the rotor blade assembly  20 , the fastener drill fixture  110  is removed from the blade  20 . 
     With reference now to  FIGS.  11 - 14   , a fastener countersink alignment fixture  130  may be applied to the rotor blade assembly  20  after formation of the plurality of fastener holes to assist a countersink operation by maintaining the proper offset and alignment relative to the previously drilled holes. As shown, the fastener countersink alignment fixture  130  includes a first plate  132  positionable adjacent a first tip skin  44  of the rotor blade assembly  20 , and a second plate  134  positionable adjacent a second, opposite tip skin  48  of the rotor blade assembly  20 . Each of the first plate  132  and second plate  134  includes a plurality of guide holes. In an embodiment, the first and second plate  132 ,  134  include holes  136   a  sized for receiving indexing pins  138 , holes  136   b  within which a countersink feature  140  (see  FIG.  11   ) is to be formed, and holes  136   c , sized receiving thumb screws  142 . Similar to each of the other fixtures described herein, the first and second plates  132 ,  134  may have identical or different configurations. 
     To use the fastener check fixture  130 , a first and second indexing pin  138   a ,  138   b  are installed into corresponding openings  136   a  in the second plate  134 . In an embodiment, the first indexing pin  138   a  is a four-way indexing pin and the second indexing pin  138   b  is a two-way indexing pin. However, embodiments including any type of indexing pin are within the scope of the disclosure. The second indexing pin  138   b  may be locked in a desired position relative to the second plate  134  through engagement with a dowel pin  144 . When initially installed, the first and second indexing pin  138   a ,  138   b  overlap with one or more adjacent holes of the plurality of guide holes  136   b . The second plate  134  is then positioned in contact with a tip skin of the blade assembly  20 , such as tip skin  48  for example, such that the first and second indexing pins  138   a ,  138   b  are received within corresponding weight cup holes  146  of the tip section  26 . Similarly, the first plate  132  is mounted in contact with an opposite tip skin  44  of the blade assembly  20 . The first plate  132  is positioned such that the first and second indexing pins  138   a ,  138   b , extending through the lower tip skin  44  of the blade assembly  20 , are received within corresponding openings  136   a  formed in the first plate  132 . A first and second knurl nut  148  are affixed to the first and second indexing pins  138   a ,  138   b , respectively, to restrict movement of the first and second indexing pins  138   a ,  138   b  relative to the rotor blade assembly  20 . 
     A plurality of thumb screws  142 , are then threaded into engagement with tip skins  44 ,  48  of the blade assembly  20  to stabilize the first and second plates  132 ,  134  relative to the blade  20 . With the first and second indexing pin  138   a ,  138   b  installed, a countersink feature  150  ( FIG.  13   ) is formed at each of the plurality of guide holes  136   b  of the second plate  134  that are not partially blocked by the indexing pins  138   a ,  138   b . In an embodiment, the countersink feature  150  is formed using a microstop  152  having a countersink cutter  154  mounted to and end thereof; as shown in  FIG.  13   . 
     Once a countersink feature  150  is formed at each of the accessible guide holes  136   b , a third indexing pin  138   c  is installed into any of the holes  136   b  having a countersink feature  150  formed therein, as shown in  FIG.  14   . The third indexing pin  138   c  is positioned so as not to obstruct any portion of an adjoining hole  136   b . Once the third indexing pin  138   c  is installed, the second indexing pin  138   b  is removed from the fixture  130 . A countersink feature  150  is then formed in both the opening  136   a  from which the second indexing pin  138   b  was removed, and the adjacent guide hole  136   b . The second indexing pin  138   b  is then reinstalled into the opening  136   a , and the first indexing pin  138   a  is removed from the fixture  130 . A countersink feature  150  is then formed in both the opening  136   a  within which the first indexing pin  138   a  was located, and an adjacent guide hole  136   b . The first indexing pin  138   a  is then reinstalled into the opening  136   a , and the third indexing pin  138   c  is removed from the fixture  130 . With the first and second indexing pin  138   a ,  138   b  reinserted into the fixture  130 , a countersink feature  150  is formed at each of the plurality of guide holes  136   b  of the first plate  132 . After the countersink features  150  are formed in each of the guide holes  136   b  of the first plate  132 , the fixture  130  may be removed from the blade assembly  20 . 
     Use of the fixtures  40 ,  110 ,  130  illustrated and described herein to generate fastener holes in a replacement tip skin eliminates the need for a five axis machine. Further, the likelihood of a replacement tip skin being outside of the allowable design criteria is reduced. 
     In addition, a method was developed that allows just the tip section of the rotor blade to be replaced without significant component replacement and subjecting the entire blade assembly through an autoclave cure cycle. A new fixture was developed that simulates autoclave pressure by the use of a pillow style air bladder, molded caul plate, and a reaction mold to constrain the bladder. Localized heat is applied by inserting the blade section and mold into an oven with removal door inserts. Alternatively heat could be applied by specialized heater elements eliminating the need for an oven. 
     The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof. 
     While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.