Patent Publication Number: US-2023138438-A1

Title: Support plate for engine casing flange

Description:
TECHNICAL FIELD 
     The application relates generally to gas turbine engines and, more particularly, to casings for gas turbine engines. 
     BACKGROUND 
     One casing in a gas turbine engine may be connected to another casing of the gas turbine engine at a joint composed of mating flanges from each casing. The casings are secured to one another by bolting their flanges together. The casings experience loads during operation of the gas turbine engine. These loads may stress the bolts and/or the mating flanges, which may cause deformation of the flanges. 
     SUMMARY 
     There is disclosed an engine casing, comprising: an annular casing wall defining a center axis, and a flange extending from the annular casing wall radially outwardly to an outer flange wall, the flange having a plurality of flange holes radially inward of the outer flange wall; a support plate against the flange, the support plate having an anti-rotation rib abutting the outer flange wall and a misalignment tab extending radially outwardly from the anti-rotation rib, the support plate having a support plate hole aligned with one flange hole of the plurality of flange holes; and a fastener extending through the support plate hole and through the one flange hole. 
     There is disclosed a support plate for an engine casing, the support plate comprising: a body having a first side and a second side opposite the first side, the body extending between an outer end and an inner end and defining a center axis; a support plate hole extending through the body between the first and second sides and about the center axis; an anti-rotation rib on one or both of the first and second sides and disposed radially outwardly of the support plate hole; and a misalignment tab extending radially outwardly from the anti-rotation rib at the outer end. 
     There is disclosed a casing assembly of an engine, the casing assembly comprising: a first casing having a first flange with first flange holes; a second casing having a second flange against the first flange, the second flange having second flange holes, at least one second flange hole of the second flange holes aligned with at least one first flange hole of the first flange holes; a support plate against one of the first flange and the second flange, the support plate having an anti-rotation rib abutting the one of the first flange and the second flange and a misalignment tab extending radially outwardly from the anti-rotation rib, the support plate having a support plate hole aligned with the at least one first flange hole and with the at least one second flange hole; and a fastener extending through the support plate hole, through the at least one first flange hole, and through the at least one second flange hole. 
     There is disclosed a method of strengthening a flange of an engine casing, the method comprising: abutting a support plate against a portion of the flange having a flange hole; aligning a support plate hole with the flange hole by abutting an outer end of the support plate against an outer wall of the flange, and by having part of the support plate protrude radially outwardly from the outer wall of the flange; and securing the support plate to the portion of the flange. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       Reference is now made to the accompanying figures in which: 
         FIG.  1    is a schematic cross sectional view of a gas turbine engine having casings; 
         FIG.  2 A  is a perspective view of a support plate mounted to flanges of the casings of  FIG.  1   ; 
         FIG.  2 B  is a cross-sectional view of the support plate and flanges taken along line IIB-IIB in  FIG.  2 A ; 
         FIG.  3    is a side elevational view of the support plate of  FIG.  2 A  incorrectly positioned with respect to the flange; 
         FIG.  4 A  is a cross-sectional view of the support plate of  FIG.  2 A  being incorrectly positioned with respect to the flange; 
         FIG.  4 B  is a cross-sectional view of the support plate of  FIG.  2 A  incorrectly positioned adjacent to the flange; 
         FIG.  5    is a perspective view of multiple support plates mounted to flanges of the casings of  FIG.  1   ; and 
         FIG.  6    is a perspective view of another support plate mounted to a flange of a casing of  FIG.  1   . 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    illustrates a gas turbine engine  10  of a type preferably provided for use in subsonic flight, generally comprising in serial flow communication a fan  12  through which ambient air is propelled, a compressor section  14  for pressurizing the air, a combustor  16  in which the compressed air is mixed with fuel and ignited for generating an annular stream of hot combustion gases, and a turbine section  18  for extracting energy from the combustion gases. Some of the components of the gas turbine engine  10  are rotatable about a longitudinal center axis  11 . 
     The gas turbine engine  10  includes a casing assembly  13 . The casing assembly  13  is an annular body housing within its interior one or more components of the gas turbine engine  10 , such as the fan  12 . The casing assembly  13  is formed by attaching two components together — a first casing  15  and a second casing  17 . One or both of the first and second casings  15 , 17  may be made up of interconnected casing sections or segments. Referring to  FIG.  1   , the casing assembly  13  surrounds the fan  12  of the gas turbine engine  10 , and may thus be referred to as a “fan casing” or a “fan casing assembly”. The casing assembly  13  in alternate embodiments may enclose or surround other components of the gas turbine engine  10 . The specific size, shape, and configuration of the casing assembly  13 , as described and/or illustrated herein, is exemplary only. Accordingly, the specific size, shape, and/or configuration of the casing assembly  13  generally, as well as portions thereof, may be selected to accommodate other components than the first and second casings  15 , 17 . 
     Referring to  FIG.  1   , the first casing  15  includes and is defined by an annular first casing wall  15 W, and the second casing  17  includes and is defined by an annular second casing wall  17 W. The first casing  15  includes a first flange  15 F and the second casing  17  includes a second flange  17 F. The first and second flanges  15 F, 17 F extend substantially radially outwardly with respect to the center axis  11  from their respective casing walls  15 W, 17 W. Alternatively, depending on the application of the casing assembly  13 , each of the first and second flanges  15 F, 17 F may be oriented at any angle relative to each respective casing wall  15 W, 17 W, or may extend from any other component, that enables the casing assembly  13  to function. In an embodiment, one or both of the first and second flanges  15 F, 17 F is a continuous body extending circumferentially relative to the center axis  11  around their respective casing walls  15 W, 17 W. In another embodiment, one or both of the first and second flanges  15 F, 17 F includes, or is made up of, discrete flange segments having a circumferential extent relative to the center axis  11 . 
     Referring to  FIG.  1   , the first and second casings  15 , 17  are secured together by being coupled along the interface of the first and second flanges  15 F, 17 F. The first and second flanges  15 F, 17 F are abutted together to mate along surfaces of the flanges  15 F, 17 F, bolts  24  are inserted through aligned holes in the first and second flanges  15 F, 17 F, and the bolts are subsequently tightened to secure the mating first and second flanges  15 F, 17 F together, as explained in greater detail below with reference to  FIGS.  2 A and  2 B . 
     Referring to  FIGS.  2 A and  2 B , the first flange  15 F includes a first flange hole  15 FH and the second flange  17 F includes a second flange hole  17 FH. The first and second flange holes  15 FH, 17 FH are configured to receive a flange bolt, or simply one of the bolts  24 . The bolt  24  is inserted through each flange hole  15 FH, 17 FH. Some or all of the first and second flange holes  15 FH, 17 FH are aligned along a hole center axis  26  of the flange holes  15 FH, 17 FH. The bolt  24  is securely fastened with a nut  28 . An optional washer or spacer may be inserted over the bolt  24  and paired with the nut  28 . The first flange  15 F defines a first flange mating surface  15 FM and an oppositely disposed first flange opposite surface  15 FO. The second flange  17 F defines a second flange mating surface  17 FM and an oppositely disposed second flange opposite surface  17 FO. The first flange mating surface  15 FM abuts against the second flange mating surface  17 FM when the first and second flanges  15 F, 17 F are coupled together. Referring to  FIGS.  2 A and  2 B , at least a portion of first and second flange mating surfaces  15 FM, 17 FM is substantially parallel to at least a portion of each respective opposite flange surface  15 FO, 17 FO. Each flange hole  15 FH, 17 FH, respectively, extends between each respective mating surface  15 FM, 17 FM and each opposite surface  15 FO, 17 FO. 
     Referring to  FIGS.  2 A and  2 B , the first flange  15 F has a generally rectangular cross-sectional profile and is formed such that the first flange mating surface  15 FM extends from an outer flange wall  15 FW of the first flange  15 F to the first casing wall  15 W. The outer flange wall  15 FW in  FIGS.  2 A and  2 B  is the radially-outermost portion of the first flange  15 F relative to the center axes  11 , 26 . The outer flange wall  15 FW in  FIGS.  2 A and  2 B  defines the radially-outermost surface of the first flange  15 F relative the center axes  11 , 26 . Referring to  FIGS.  2 A and  2 B , the first flange mating surface  15 FM is substantially parallel to the first flange opposite surface  15 FO, and the center axis  26  of the first flange hole  15 FH is oriented substantially perpendicularly to the surfaces  15 FM, 15 FO. The first flange hole  15 FH is positioned radially inwardly of the outer flange wall  15 FW, with respect to the hole center axis  26 . Similarly, the second flange mating surface  17 FM extends from a radially-outer wall of the second flange  17 F to the second casing wall  17 W, and is substantially perpendicular to the second casing wall  17 W. 
     Referring to  FIGS.  2 A and  2 B , the first casing wall  15 W and the first flange  15 F meet at a joint  15 J. The joint  15 J has, or is composed of, a fillet  15 R. The fillet  15 R is a rounding of the corner of the joint  15 J and is defined by a radius and curvature. The fillet  15 R forms the transition between the first casing wall  15 W and the first flange  15 F. The fillet  15 R is along, and forms part of, the first flange opposite surface  15 FO and is positioned opposite to the first flange mating surface  15 FM. 
     During operation of the gas turbine engines  10 , loads are generated and may act on the casing assembly  13 . For example, in the configuration where the casing assembly  13  encloses the fan  12  of the gas turbine engine  10 , a high event load such as fan blade off, in which a fan blade separates from the fan  12  and impacts the casing assembly  13 , may cause stress to the casings  15 , 17  and/or to their flanges  15 F, 17 F. It has been observed that such high event loads, in addition to more routine loads imparting stresses over multiple operating cycles of the gas turbine engine  10 , may place the flanges  15 F, 17 F under tensile loads and cause one or both of them to “peel” apart (i.e. to separate from each other), or may cause their flange holes  15 FH, 17 FH to distort in shape. 
     In order to compensate for any such anticipated loading, or to reinforce a flange  15 F, 17 F that may have already experienced the effects of such loading, the casing assembly  13  is provided with one or more support plates  30 . The support plates  30  may be added to an existing flange  15 F, 17 F that requires additional structural support or reinforcement against loads which may cause distortion of the flange holes  15 FH, 17 FH or separation of the flanges  15 F, 17 F under high event loads. The support plates  30  allow for strengthening a flange  15 F, 17 F of the gas turbine engine  10  around the flange hole  15 FH, 17 FH without having to remove the casing  15 , 17  containing the flange  15 F, 17 F for repair or replacement. By reinforcing or strengthening a flange  15 F, 17 F, the support plates  30  may allow for running the gas turbine engine  10  at loads higher than those for which the flange  15 F, 17 F was designed, and thereby possibly allow for continued use of the flange  15 F, 17 F without having to re-engineer it or the casing  15 , 17 . 
     Referring to  FIGS.  2 A and  2 B , the support plate  30  has a body  32 . The body  32  is a planar rectangular prism which has a thickness defined between a first side  32 M and a second side  32 O that is opposite to the first side  32 M. The body  32  also has a height defined between an outer end  32 U and an inner end  32 I. The body  32  has a support plate hole  32 H that extends through the body between the first and second sides  32 M, 32 O. The support plate hole  32 H is centered about a plate center axis  32 A of the body  32 . The first and second sides  32 M, 32 O are spaced apart from each other in an axial direction relative to the plate center axis  32 A. The outer and inner ends  32 O, 32 I are spaced apart from each other in a radial direction relative to the plate center axis  32 A, to define the height of the body  32 . 
     In the configuration of the support plate  30  in  FIGS.  2 A and  2 B , the support plate  30  is a “single-hole” support plate  30  because it has only one support plate hole  32 H. The single-hole support plate  30  increases the versatility of the support plate  30 , because it allows the support plate  30  to be used to reinforce any single flange hole  15 FH, 17 FH, which may be desirable for flanges  15 F, 17 F that do not have repeating hole patterns. The versatility provided by the single-hole support plate  30  may also allow it to be used to reinforce the flange  15 F, 17 F at “empty” flange holes  15 FH, 17 FH that are not already occupied by harness brackets or the like. However, other configurations of the support plate  30  are possible and within the scope of the present disclosure. For example, in another possible configuration of the support plate  30 , the support plate  30  has multiple support plate holes  32 H and is used to reinforce a flange  15 F, 17 F which has a repeating hole pattern. This configuration of the support plate  30  may include an annular or ring body  32 , or a circumferentially-elongated body  32 , each of which has multiple support plate holes  32 H which are circumferentially spaced apart. 
       FIGS.  2 A and  2 B  show the support plate  30  mounted and secured against the first flange  15 F of the first casing  15 . When mounted to the first flange  15 F, the first side  32 M of the body  32  abuts against, and mates with, the first flange opposite surface  15 FO and is parallel with the first flange mating surface  15 FM. When mounted to the first flange  15 F, the outer end  32 U is the radially-outer end of the body  32  relative to the hole center axes  26 , and the inner end  32 I is the radially-inner end of the body  32  and is positioned closer to the first casing wall  15 W than the outer end  32 U. When mounted to the first flange  15 F, the support plate hole  32 H is aligned with the first and second flange holes  15 FH, 17 FH such that the plate center axis  32 A is collinear with the hole center axes  26  of the first and second flange holes  15 FH, 17 FH. The bolt  24  is inserted through the support plate hole  32 H, through the first flange hole  15 FH, and through the second flange hole  17 FH. The support plate  30  is secured to the first flange  15 F by being fastened to the first flange  15 F with the bolt  24 , and by tightening the bolt  24 . A bolt head  24 H abuts against the second side  32 O of the body  32 . 
     Although  FIGS.  2 A and  2 B  show one support plate  30  secured to the first and second flanges  15 F, 17 F around one pair of their flange holes  15 H, 17 H, the casing assembly  13  may have multiple support plates  30  each secured to a corresponding pair of first and second flange holes  15 FH, 17 FH. One possible example of such a configuration is shown in  FIG.  5   .  FIG.  5    is an example of casing assembly  13  in which the flanges  15 F, 17 F do not have repeating hole patterns. Furthermore, although  FIGS.  2 A and  2 B  show a single-hole support plate  30 , the support plate  30  may have multiple support plate holes  32 H, each of which is aligned with one pair of aligned flange holes  15 FH, 17 FH of the flanges  15 F, 17 F. In the configuration of the flanges  15 F, 17 F in  FIGS.  2 A and  2 B , the first flange  15 F is thinner than the second flange  17 F (when measured along an axial direction relative to the aligned center axes  26 ), such that only one support plate  30  may be needed to reinforce the casing assembly  13  at the first flange  15 F, the second flange  17 F being potentially thick enough to adequately resist bending or peeling. However, the casing assembly  13  in another embodiment has a second support plate  30  secured to the second flange  17 F, either in addition to the first support plate  30  secured to the first flange  15 F or not. Therefore, the description herein related to the support plate  30  and its features secured to the first flange  15 F applies mutatis mutandis to a second support plate  30  secured to the second flange  17 F. 
     The support plate  30  has one or more features which help to orient it correctly with respect to the first flange  15 F, and which prevent it from being installed incorrectly on the first flange  15 F. Some of these features are now described in greater detail. 
     Referring to  FIGS.  2 A and  2 B , one of these features is an anti-rotation rib  40  of the support plate  30 . The anti-rotation rib  40  helps to prevent the support plate  30  from rotating about the plate center axis  32 A when it is being applied against the first flange  15 F and secured in place by torqueing the bolt  24 . The anti-rotation rib  40  (sometimes referred to herein simply as the “rib  40 ”) thus helps the support plate  30  to have the correct orientation when the support plate  30  is being secured to the first flange  15 F. The rib  40  also helps to prevent the support plate  30  from being installed incorrectly on the flange  15 F by helping to ensure that the support plate  30  has the correct orientation. The rib  30  thus contributes to making the support plate  30  “mistake-proof”, or less prone to being installed incorrectly. 
     The rib  40  may have any suitable shape or form to achieve such functionality. For example, and referring to  FIGS.  2 A and  2 B , the rib  40  includes a body  41  that has a height measured radially relative to the plate center axis  32 A. The body  41  has a rib wall  42  that lies in a single straight plane (or possible a singly slightly curved plane). The rib  40  has a circumferential extent relative to the hole center axes  26  when the support plate  30  is installed on the first flange  15 F, and is present on opposite circumferential sides of the hole center axes  26 . The rib  40  is positioned between the outer and inner ends  32 U, 32 I of the body  32  of the support plate  30 . The rib  40  is located on the first side  32 M of the body  32 , and extends transversely to the first side  32 M toward the first flange  15 F. 
     In order to achieve its anti-rotation function, the rib  40  abuts against the outer flange wall  15 FW of the first flange  15 F when the support plate  30  is positioned against the first flange  15 F. Referring to the configuration of the rib  40  in  FIGS.  2 A and  2 B , the rib wall  42  defines or forms a radially-innermost surface of the rib  40 , relative to the hole center axes  26 . This radially-innermost surface abuts against, and mates with, part of the outer flange wall  15 FW overlying the first flange hole  15 FH. The outer flange wall  15 FW forms an exposed, radially-outermost surface of the first flange  15 F relative to the hole center axes  26 . The rib  40  is thus positioned radially outwardly of the outer flange wall  15 FW, relative to the hole center axes  26 , when the support plate  30  is placed against the first flange  15 F. The abutment of the rib wall  42  against the outer flange wall  15 FW stops the support plate  30  from rotating about the plate center axis  32 A when the bolt  24  is torqued. The anti-rotation functionality provided by the rib  40  may be beneficial to the single-hole support plate  30  of  FIGS.  2 A and  2 B , which may have a greater tendency to rotate about the plate center axis  32 A when the bolt  24  is torqued. The configuration of the rib  40  in  FIGS.  2 A and  2 B  shows the rib  40  extending over and overlaying most of the outer flange wall  15 FW in an axial direction relative to the hole center axes  26 . In another possible configuration of the rib  40 , the rib  40  is axially longer than shown in  FIGS.  2 A and  2 B  such that it extends axially over and overlays both the outer flange wall  15 FW of the first flange  15 F and some or all of the outer flange wall  17 FW of the second flange  17 F, such that the rib  40  abuts both flanges  15 F, 17 F. 
       FIGS.  2 A and  2 B  show another feature of the support plate  30 , a misalignment tab  50 , which helps to orient the support plate  30  correctly with respect to the first flange  15 F, and which prevents it from being installed incorrectly on the first flange  15 F. The misalignment tab  50  helps to prevent the plate center axis  32 A from aligning with the hole center axis  26  of the first flange  15 F when the support plate  30  is incorrectly oriented with respect to the first flange  15 F, as explained in greater detail below. Since the center axes  32 A, 26  are misaligned when the support plate  30  is incorrectly oriented, the misalignment tab  50  helps to prevent the support plate  30  from being installed incorrectly on the first flange  15 F because the bolt  24  cannot be inserted through the misaligned support plate and first flange holes  32 H, 15 FH. The misalignment tab  50  (sometimes referred to herein simply as the “tab  50 ”) thus helps the support plate  30  to have the correct orientation when the support plate  30  is being secured to the first flange  15 F. The tab  50  also helps to prevent the support plate  30  from being installed incorrectly on the flange  15 F, thereby helping to make the support plate  30  “mistake-proof”, or less prone to being installed incorrectly. 
     The tab  50  may have any suitable shape or form to achieve such functionality. For example, and referring to  FIGS.  2 A and  2 B , the tab  50  extends radially outwardly from the rib  40 , relative to the plate center axis  32 A. The tab  50  is positioned radially outwardly of the support plate hole  32 H, relative to the plate center axis  32 A. The tab  50  thus forms a radially-outward extension of the support plate  30 , such that part of the support plate  30  (i.e. the tab  50 ) protrudes radially outwardly from the outer flange wall  15 W when the support plate  30  is secured to the first flange  15 F. The height of the tab  50  (measured along a direction radial to the plate center axis  32 A) contributes to misaligning the holes  32 H, 15 FH when the support plate  30  is incorrectly oriented with respect to the first flange  15 F. In the configuration of the tab  50  shown in  FIGS.  2 A and  2 B , the tab  50  has a circumferential extent relative to the hole center axes  26  when the support plate  30  is installed on the first flange  15 F, and is present directly radially outwardly of the holes  32 H, 15 FH and radially aligned therewith when the support plate  30  is secured to the first flange  15 F. The tab  50  is centered on the support plate  30 . The tab  50  is positioned at the outer end  32 U of the body  32  of the support plate  30 , and defines the radially-outermost surface of the support plate  30 , relative to the hole center axes  26 , when the support plate  30  is secured to the first flange  15 F. 
     Referring to the configuration of the tab  50  in  FIGS.  2 A and  2 B , the tab  50  includes one or more protruding portions  52  and one or more recessed portions  54 . The protruding portion  52  is positioned radially outwardly of the recessed portions  54  relative to the plate center axis  32 A. The protruding portion  52  is thus a bump forming the outer end  32 U of the support plate  30  which helps to prevent the holes  32 H, 15 FH from aligning when the support plate  30  is incorrectly oriented with respect to the first flange  15 F, as explained in greater detail below. Referring to the configuration of the tab  50  in  FIGS.  2 A and  2 B , the tab  50  defines a outer tab wall  56  which defines the radially-outermost surface of the support plate  30 , relative to the aligned axes  32 A, 26  when the support plate  30  is secured to the first flange  15 F. The outer tab wall  56  along the recessed portions  54  is positioned radially closer to the plate center axis  32 A than the outer tab wall  56  along the protruding portion  52 . The outer tab wall  56  along the protruding portion  52  lies in a single straight plane that is perpendicular to a line being radial to the plate center axis  32 A. The outer tab wall  56  along the recessed portions  54  lies in a curved plane that slopes toward the plate center axis  32 A from the outer tab wall  56  along the protruding portion  52 . In one possible configuration, the protruding portion  52  has a height measured along a radial line from the plate center axis  32 A that is greater than a distance between the first casing wall  15 W and the radially-innermost surface of the first flange hole  15 . In another possible configuration, the protruding portion  52  has a height measured along a radial line from the plate center axis  32 A that is less than half the distance between the first casing wall  15 W and the radially-innermost surface of the first flange hole  15 . It will thus be appreciated that the height of the tab  50  may be any value which causes misalignment of the holes  32 H, 15 FH when the support plate  30  is incorrectly oriented with respect to the first flange  15 F. Determining the height of the tab  50  may involve identifying the scenarios where the bolt  24  may still be inserted through the misaligned holes  32 H, 15 FH, and selecting the height to avoid these scenarios. 
     Other configurations for the tab  50  are possible. For example, the tab  50  in another possible configuration has only a single protruding portion  52  and no recessed portions  54 . For example, in another possible configuration of the support plate  130  and referring to  FIG.  6   , the tab  150  has two protruding portions  152  on opposite circumferential ends of the body  132 , where the protruding portions  152  are spaced apart by a single recessed portion  154 . In the configuration of  FIG.  6   , the tab  150  is on either end of the support plate  130 , such that the recessed portion  154  provides a clearance which allows for a bracket  160  to be attached to the support plate  130 . The bracket  160  may be used to attach objects such as a wiring harness to the support plate  130 , and thus to the first flange  15 F. 
     The ability of the misalignment tab  50  to orient the support plate  30  correctly with respect to the first flange  15 F, and to prevent the support plate  30  from being installed incorrectly on the first flange  15 F, may be better appreciated with reference to  FIGS.  3  to  4 B . The support plate  30  is shown in  FIGS.  3  to  4 B  in an incorrect orientation with respect to the first flange  15 F, in which the tab  50  is positioned “upside down” (i.e. abutting the first casing wall  15 W). When the support plate  30  is positioned incorrectly with respect to the first flange  15 F,  FIGS.  3  and  4 B  show that the protruding portion  52  of the tab  50  prevents the plate center axis  32 A from aligning with the hole center axis  26 . Thus, the tab  50  stops the support plate and first flange holes  32 H, 15 FH from being aligned when the support plate  30  is positioned incorrectly with respect to the first flange  15 F, such that the bolt  24  is prevented from being inserted into the holes  32 H, 15 FH and thus the support plate  30  cannot be secured to the first flange  15 F. The installer will only be able to secure the support plate  30  to the first flange  15 F by flipping the support plate  30  so that the misalignment tab  50  is radially outward. In this way, the misalignment tab  50  contributes to making the support plate  30  “mistake proof”, because it allows the support plate  30  to be secured to the first flange  15 F only when the support plate  30  has the correct orientation. 
     Another misalignment or mistake-proof feature of the tab  50  is also shown in  FIGS.  4 A and  4 B . The edges of the protrusion portion  52  of the tap  50  are straight and free of bevels or chamfers. These straight edges prevent the first side  32 M of the support plate  30  from being placed flush against the first flange mating surface  15 FM of the first flange  15 F, because the straight edges of the protrusion portion  52  do not conform to the shape of the fillet  15 R at the joint  15 J between the first casing wall  15 W and the first flange  15 F. If the installer mistakenly moves the support plate  30  radially outward to place the first side  32 M of the support plate  30  flush against the first flange mating surface  15 FM, then the center axes  32 A, 26  will be misaligned such that the bolt  24  will not be able to be inserted through the support plate and first flange holes  32 H, 15 FH. 
     Referring to  FIGS.  2 A and  2 B , the support plate  30  and its mistake-proof features disclosed herein help reduce the possibility, and may even completely prevent, the incorrect installation of the support plate  30  against the first flange  15 F. This allows for a substantially or completely “mistake-proof” assembly of the support plate  30  with the first flange  15 F, such that the installer may perform such installation “blind” (i.e. without actually seeing the first flange  15 F). Such a blind installation may be performed in an aircraft engine  10  which is still mounted to a wing of the aircraft, and in which it is difficult to see or access the first flange  15 F. The inability to see the support plate  30  during its attachment to the first flange  15 F, which might otherwise have prevented the installation of the support plate  30  or required dismounting the engine  10 , may no longer be an impediment to the installer from completing the work, because the mistake-proof features of the support plate  30  may allow the installer to still correctly attach the support plate  30  to the first flange  15 F and thereby reinforce the first flange  15 F. 
     Referring to  FIGS.  2 A and  2 B , when properly installed against the first flange  15 F, the support plate  30  helps to structurally reinforce or strengthen the first flange  15 F. The inner end  32 I of the body  32  of the support plate  30  is chamfered, or has a chamfer  34 . One or both sides  32 M, 32 O of the body  32  at the inner end  32 I has a transitional wall  34 T of the chamfer  34 . The transitional wall  34 T extends between a side wall  32 W of the body  32  on the first or second sides  32 M, 32 O and a bottom wall  32 B of the body  32  defining the radially-innermost surface of the body  32  relative to the aligned axes  32 A, 26 . The transitional wall  34 T may be a bevel, radius or any other surface that is shaped to be complementary to a shape of the fillet  15 R, so that the chamfer  34  can be abutted against, and mate with, the fillet  15 R at the joint  15 J between the first casing wall  15 W and the first flange  15 F. For example, in the configuration of the support plate  30  in  FIGS.  2 A and  2 B , the transitional wall  34 T is curved over its length, such that chamfer  34  is defined by a radius of curvature that matches or is similar to a radius of curvature of the fillet  15 R. The curvature of the chamfer  34  is complementary to the curvature of the fillet  15 R (e.g. the chamfer  34  has a convex curvature matching the concave curvature of the fillet  15 R), so that they can be mated together. 
     The complementary shapes between the chamfer  34  and the fillet  15 R may allow for tension loads acting on the casing walls  15 W, 17 W to be transferred to the support plate  30  at the chamfer  34 . The chamfer  34  allows the inner end  32 I of the support plate  30  to bear a portion of the load along the fillet  15 R and parts of the casing wall  15 W proximate the fillet  15 R. The chamfer  34  may thus provide additional load bearing capacity to the support plate  30 . By reinforcing the joint  15 J between the first casing wall  15 W and the first flange  15 F, the chamfer  34  of the support plate  30  helps to reinforce the fillet  15 R during flange loading, and may reduce the tension loads causing the flanges  15 F, 17 F to “peel” apart (i.e. to separate from each other). By abutting against the joint  15 J at the fillet  15 R, the chamfer  34  may help to lower bending at the flange  15 F, 17 F. The complementary shapes between the chamfer  34  and the fillet  15 R may allow for clearances or gaps between the support plate  30  and the fillet  15 R to be minimized or eliminated, helping to ensure that the support plate  30  can be installed flush with the first flange  15 F and thus will not interfere with the fillet  15 R which might impact the bolt clamp stack. 
     Referring to  FIGS.  2 A and  2 B , the body  32  of the support plate  30  is symmetrical. As explained in greater detail below, the symmetry of the support plate  30  contributes to its mistake-proof attributes. The support plate  30  defines a first support plate plane P 1 . The first support plate plane P 1  is parallel to the first flange  15 F when the support plate  30  is secured to the first flange  15 F. The first support plate plane P 1  is parallel to the first flange mating and opposite surfaces  15 FM, 15 FO of the first flange  15 F when the support plate  30  is secured to the first flange  15 F. The first support plate plane P 1  (sometimes referred to herein simply as “the first plane P 1 ”) extends through the body  32  of the support plate  30 . The first plane P 1  extends through the body  32  of the support plate  30  between the first side  32 M and the second side  32 O. The first plane P 1  extends through the body  32  of the support plate  30  between the first side  32 M and the second side  32 O, and is spaced equidistantly from the first and second dies  32 M, 32 O. The first plane P 1  is parallel to the first side  32 M and the second side  32 O. The first plane P 1  is perpendicular to the plate center axis  32 A. The first plane P 1  is perpendicular to the aligned center axes  32 A, 26  when the support plate  30  is secured to the first flange  15 F. 
     The support plate  30  defines a second support plate plane P 2 . The second support plate plane P 2  is perpendicular to the first flange  15 F when the support plate  30  is secured to the first flange  15 F. The second support plate plane P 2  is perpendicular to the first flange mating and opposite surfaces  15 FM, 15 FO of the first flange  15 F when the support plate  30  is secured to the first flange  15 F. The second support plate plane P 2  (sometimes referred to herein simply as “the second plane P 2 ”) extends through the body  32  of the support plate  30 . The second plane P 2  contains the plate center axis  32 A of the body  32 , extends radially from the plate center axis  32 A, and has an upright or vertical orientation when the support plate  30  is secured to the first flange  15 F. The second plane P 2  is perpendicular to the first plane P 1 . The second plane P 2  is perpendicular to the first and second sides  32 M, 32 O of the body  32 . The second plane P 2  may be considered to be a center plane because it contains the plate center axis  32 A. 
     Some of the mistake-proof features of the support plate  30  are symmetrical about one or both of the first and second planes P 1 ,P 2 . For example, and referring to  FIG.  2 B , the rib  40  includes a first rib  40 A and a second rib  40 B. The first and second ribs  40 A, 40 B extend from the body  32  in a direction that is perpendicular to the first plane P 1 . The first rib  40 A extends from the first side  32 M of the body  32  in a direction that is perpendicular to the first plane P 1  and also extends toward the outer flange wall  15 FW. The first rib  40 A is thus able to jut out over, and abut against, the outer flange wall  15 FW. The second rib  40 B extends from the second side  32 O of the body  32  in a direction that is perpendicular to the first plane P 1  and also extends away from the outer flange wall  15 FW. Referring to  FIG.  2 B , the first and second anti-rotation ribs  40 A, 40 B are symmetric about the first plane P 1 . The first and second ribs  40 A, 40 B have reflectional symmetry (i.e. line or mirror symmetry), in that the first support plate plane P 1  bisects the body  32  of the support plate  30 , dividing it into two pieces in which the ribs  40 A, 40 B are mirror images of each other. The symmetry of the ribs  40 A, 40 B about the first plane P 1  and their presence on both sides  32 M, 32 O of the support plate  30  helps to ensure that the support plate  30  will be correctly positioned against the first flange  15 F, because the installer can abut either side  32 M, 32 O of the support plate  30  against the first flange  15 F. This contributes to the mistake-proof attributes of the support plate  30 , and further assists with a blind installation of the support plate  30 . 
     Another of the mistake-proof features of the support plate  30  that is symmetrical about one or both of the first and second planes P 1 ,P 2  is the misalignment tab  50 . For example, and referring to  FIG.  2 A , the tab  50  is symmetric about the second plane P 2 . Referring to  FIG.  2   , the protruding and recessed portions  52 , 54  of the tab  50  are symmetric about the second plane P 2 . The tab  50  has reflectional symmetry (i.e. line or mirror symmetry), in that the second support plate plane P 2  bisects the body  32  of the support plate  30 , dividing it into two pieces in which the protruding and recessed portions  52 , 54  are mirror images of each other. The symmetry of the tab  50  about the second plane P 2  helps to ensure that the support plate  30  will be correctly positioned against the first flange  15 F, because the installer can abut either side  32 M, 32 O of the support plate  30  against the first flange  15 F. This contributes to the mistake-proof attributes of the support plate  30 , and further assists with a blind installation of the support plate  30 . 
     Another of the mistake-proof features of the support plate  30  that is symmetrical about one or both of the first and second planes P 1 ,P 2  is the chamfer  34 . For example, and referring to  FIG.  2 B , the chamfer  34  includes a first chamfer  34 A and a second chamfer  34 B. The first and second chamfers  34 A, 34 B are at the inner end  32 I. The first and second chamfers  34 A, 34 B are shaped such that their transitional walls  34 T slow toward the first plane P 1  from the side walls  32 W of the body, and also slope toward each other. The first chamfer  34 A is present on the first side  32 M of the body  32 , and the second chamfer  34 B is present on the second side  32 O of the body  32 . The first and second chamfers  34 A, 34 B are symmetric about the first plane P 1 . Referring to  FIG.  2 B , the first and second chamfers  34 A, 34 B have reflectional symmetry (i.e. line or mirror symmetry), in that the first support plate plane P 1  bisects the body  32  of the support plate  30 , dividing it into two pieces in which the chamfers  34 A, 34 B are mirror images of each other. The symmetry of the chamfers  34 A, 34 B about the first plane P 1  and their presence on both sides  32 M, 32 O of the support plate  30  (i.e a “double chamfer” at the inner end  32 I) helps to ensure that the support plate  30  will be correctly positioned against the first flange  15 F, because the installer can abut either side  32 M, 32 O of the support plate  30  against the first flange  15 F. This contributes to the mistake-proof attributes of the support plate  30 , and further assists with a blind installation of the support plate  30 . 
     The support plate  30  thus has features that are symmetrical in perpendicular planes P 1 ,P 2  of the support plate  30 . This symmetry contributes to making the support plate  30  mistake proof, because it allows for either side  32 M, 32 O of the support plate  30  to be installed against the first flange  15 F. This symmetry of the support plate  30 , in combination with the anti-rotation rib  40  and the misalignment tab  50 , helps to prevent installation of the bolt  24  until the support plate  30  is positioned in the correct configuration to reinforce the structural integrity of the first flange  15 F. 
     Referring to another possible configuration of the support plate  130  in  FIG.  6   , the first and second ribs  140 A, 140 B extend perpendicularly outwardly from their respective sides  132 M, 132 O of the body  132  of the support plate  130 . The two protruding portions  152  of the tab  150  are spaced inwardly toward the middle of the body  132  from the first and second ribs  140 A, 140 B. The features of the support plate  130  shown in  FIG.  6    have the same symmetry about the first and second planes P 1 ,P 2  described above. The description provided above of the features of the support plate  30  and their attributes applies mutatis mutandis to the features of the support plate  130  in  FIG.  6   . 
     In operation, and referring to  FIGS.  2 A and  2 B , the support plate  30 , 130  may be attached to the first flange  15 F as follows. The installer first abuts either side  32 M, 32 O of the body  32  against the first flange mating surface  15 FM. If the installer feels or observes that the body  32  is not flush against the first flange mating surface  15 FM, they installer may move the body  32  until 1) one of the ribs  40 A, 40 B is abutting against the outer flange wall  15 FW, 2) the protruding portion  52  of the misalignment tab  50  extends radially outwardly of the outer flange wall  15 FW, and 3) one of the chamfers  34 A, 34 B is flush against the fillet  15 R of the joint  15 J between the first casing wall  15 W and the first flange  15 F. The holes  32 H, 15 FH will only be aligned if all three of these events occur, such that the support plate  30 , 130  can only be secured to the first flange  15 F with the bolt  24  in the correct position when all three of these events have occurred. 
     Referring to  FIGS.  2 A and  2 B , there is disclosed a method of reinforcing or strengthening the flange  15 F of the casing  15 . The method includes abutting the support plate  30 , 130  against a portion of the flange  15 F. The method includes aligning the support plate hole  32 H with the flange hole  15 FH by abutting an outer end of the support plate  30 , 130  against the outer flange wall  15 FW, and by having part of the support plate  30 , 130  protrude radially outwardly from the outer flange wall  15 W. The method includes securing the support plate  30 , 130  to the portion of the flange  15 F. There is also disclosed a method of retrofitting a flange  15 F of an engine casing  15  with the support plate  30 , 130 , based on the disclosure herein. There is also disclosed a method of repairing a flange  15 F of an engine casing  15  with the support plate  30 , 130 , based on the disclosure herein. These methods may include inspecting the flange  15 F for damage, and validating the installation of the support plate  30 , 130 , such as with a stress engineer. There is also disclosed a method of blindly installing a support plate  30 , 130  on a flange  15 F of an engine casing  15 , based on the disclosure herein. There is also disclosed a method of replacing an existing support plate on a flange  15 F of an engine casing  15  using the support plate  30 , 130  disclosed herein, based on the disclosure herein. These methods may include preventing the support plate  30 , 130  from being secured in every or any orientation except a single orientation in which the support plate hole  32 H is aligned with the flange hole  15 FH. 
     The embodiments described in this document provide non-limiting examples of possible implementations of the present technology. Upon review of the present disclosure, a person of ordinary skill in the art will recognize that changes may be made to the embodiments described herein without departing from the scope of the present technology. Yet further modifications could be implemented by a person of ordinary skill in the art in view of the present disclosure, which modifications would be within the scope of the present technology.