Patent Description:
In the assembly of gas turbine engines or other equipment, bolts or other fasteners may be used to securely mount two or more components together. In some cases, one side of a fastener may not be physically accessible at one or more points in the assembly process (e.g., a "blind assembly"). There is a risk during the assembly process that one or more fasteners of a blind assembly may become partially or fully dislodged from their intended fastening position before they can be fully secured (e.g., using a nut). The one or more dislodged fasteners can potentially fall into a portion of the equipment which is no longer accessible. Some amount of disassembly of the equipment may then be needed to recover the one or more dislodged fasteners, thereby increasing the time and cost associated with equipment assembly. Accordingly, improved systems and methods for retaining fasteners during assembly are needed.

<CIT> discloses a prior art turbomachine component connection.

<CIT> discloses a prior art retention hardware.

<CIT> discloses a prior art fastening system for fan and shaft interconnection.

<CIT> discloses a prior art turbomachine.

<CIT> discloses a prior art shield system for a gas turbine engine.

According to an aspect of the present disclosure, there is provided a flange assembly as recited in claim <NUM>.

In any of the aspects or embodiments described above and herein, the secondary flange body may include an annular recess formed between the secondary bolt aperture and the first secondary surface and the clip may be axially positioned within the annular recess.

In any of the aspects or embodiments described above and herein, the flange assembly may further include a washer disposed about the bolt body and positioned between the primary flange and the second flange. The washer may be positioned axially within the recess of the secondary flange body.

In any of the aspects or embodiments described above and herein, the washer may be positioned radially outside of the clip.

In any of the aspects or embodiments described above and herein, the primary flange body may include an annular projection. The annular projection may extend axially from the second primary surface toward the first secondary surface. The annular projection may be positioned within the recess of the secondary flange body.

In any of the aspects or embodiments described above and herein, the annular projection may be positioned radially outside of the clip.

In any of the aspects or embodiments described above and herein, a first radial portion of the clip may be positioned radially inside the groove and a second radial portion of the clip may be positioned radially outside of the groove.

In any of the aspects or embodiments described above and herein, the primary flange body may include an annular recess extending from the primary bolt aperture to the second primary surface. The annular recess may be positioned axially adjacent the clip. The annular recess may include an axially extending surface and a radially extending surface. The axially extending surface may be spaced from the annular surface of the bolt body by a distance and the distance may be less than a cross-sectional diameter of the clip.

In any of the aspects or embodiments described above and herein, the primary flange body may include an annular chamfer extending from the primary bolt aperture to the second primary surface. The annular chamfer may be positioned axially adjacent the clip.

In any of the aspects or embodiments described above and herein, the annular chamfer may include a chamfer surface extending between an inner radial chamfer end and an outer radial chamfer end.

In any of the aspects or embodiments described above and herein, the chamfer surface may be flat in a direction extending between the inner radial chamfer end and the outer radial chamfer end.

In any of the aspects or embodiments described above and herein, the clip may include a cross-sectional flat surface.

In any of the aspects or embodiments described above and herein, the cross-sectional flat surface may be substantially parallel to the chamfer surface of the annular chamfer of the primary flange body.

In any of the aspects or embodiments described above and herein, the chamfer surface may be disposed at an angle relative to a radial line. The angle may be between <NUM> and <NUM> degrees.

In any of the aspects or embodiments described above and herein, the chamfer surface may be convex between the inner radial chamfer end and the outer radial chamfer end.

In any of the aspects or embodiments described above and herein, the chamfer surface may be concave between the inner radial chamfer end and the outer radial chamfer end.

There is also provided a method for assembling a flange assembly as recited in claim <NUM>.

In any of the aspects or embodiments described above and herein, the secondary flange body may include an annular recess formed between the secondary bolt aperture and the first secondary surface. The clip may be axially positioned within the annular recess, subsequent to the step of installing the secondary flange.

In any of the aspects or embodiments described above and herein, the primary flange body may include an annular chamfer extending from the primary bolt aperture to the second primary surface. The annular chamfer may be positioned axially adjacent the clip, subsequent to the step of installing the clip onto the bolt.

The present disclosure, and all its aspects, embodiments and advantages associated therewith will become more readily apparent in view of the detailed description provided below, including the accompanying drawings.

Referring to <FIG>, an exemplary gas turbine engine <NUM> is schematically illustrated. The gas turbine engine <NUM> is disclosed herein as a two-spool turbofan engine that generally includes an inlet <NUM>, a fan section <NUM>, a compressor section <NUM>, a combustor section <NUM>, a turbine section <NUM>, and an exhaust section <NUM>. The fan section <NUM> drives air along a bypass flow path <NUM> while the compressor section <NUM> drives air along a core flow path <NUM> for compression and communication into the combustor section <NUM> and then expansion through the turbine section <NUM>. Although depicted as a turbofan gas turbine engine in the disclosed non-limiting embodiments, it should be understood that the concepts described herein are not limited to use with turbofans as the teachings may be applied to other types of gas turbine engines including those with single-spool or three-spool architectures. Moreover, aspects of the present disclosure are not limited in application to gas turbine engines and may be applicable to other aircraft propulsion systems as well.

The gas turbine engine <NUM> of <FIG> includes a low-pressure spool <NUM> and a high-pressure spool <NUM> mounted for rotation about a longitudinal centerline <NUM> (e.g., a rotational axis) of the gas turbine engine <NUM> relative to an engine static structure <NUM> (e.g., an engine case). The low-pressure spool <NUM> includes a low-pressure shaft <NUM> that interconnects a fan <NUM>, a low-pressure compressor <NUM>, and a low-pressure turbine <NUM>. The high-pressure spool <NUM> includes a high-pressure shaft <NUM> that interconnects a high-pressure compressor <NUM> and a high-pressure turbine <NUM>. It is to be understood that "low pressure" and "high pressure" or variations thereof as used herein are relative terms indicating that the high pressure is greater than the low pressure. An annular combustor <NUM> is disposed between the high-pressure compressor <NUM> and the high-pressure turbine <NUM> along the longitudinal centerline <NUM>. The low-pressure shaft <NUM> and the high-pressure shaft <NUM> are concentric and rotate about the longitudinal centerline <NUM>.

Airflow along the core flow path <NUM> is compressed by the low-pressure compressor <NUM>, then the high-pressure compressor <NUM>, mixed and burned with fuel in the combustor <NUM>, and then expanded over the high-pressure turbine <NUM> and the low-pressure turbine <NUM>. The low-pressure turbine <NUM> and the high-pressure turbine <NUM> rotationally drive the low-pressure spool <NUM> and the high-pressure spool <NUM>, respectively, in response to the expansion.

<FIG> illustrate a portion of the compressor section <NUM> including a mating interface between the low-pressure compressor <NUM> and the low-pressure shaft <NUM>. The low-pressure compressor <NUM> of <FIG> includes a low-pressure compressor module <NUM> including a plurality of circumferentially-spaced compressor blades <NUM>. The compressor blades <NUM> are positioned within the core flow path <NUM> and mounted for rotation about the longitudinal centerline <NUM>. The low-pressure shaft <NUM> includes a low-pressure shaft flange <NUM> (hereinafter a "primary flange <NUM>"). The low-pressure compressor module <NUM> further includes a low-pressure compressor flange <NUM> (hereinafter a "secondary flange <NUM>"), for example, at an upstream end of the low-pressure compressor module <NUM>. As will be discussed in further detail, the primary flange <NUM> and the secondary flange <NUM> are fixedly mounted to one another at a flange assembly <NUM>.

Referring to <FIG>, the primary flange <NUM> includes a primary flange body <NUM> extending outward from the longitudinal centerline <NUM> to a distal end <NUM>. The primary flange body <NUM> includes a first primary surface <NUM> and a second primary surface <NUM> opposite the first primary surface <NUM>. The primary flange body <NUM> defines a plurality of circumferentially-spaced primary bolt apertures <NUM> extending through the primary flange body <NUM> from the first primary surface <NUM> to the second primary surface <NUM>. The secondary flange <NUM> includes a secondary flange body <NUM>. The secondary flange body <NUM> includes a first secondary surface <NUM> and a second secondary surface <NUM> opposite the first secondary surface <NUM>. The first secondary surface <NUM> of the secondary flange body <NUM> is positioned in contact with the second primary surface <NUM> of the primary flange body <NUM>. The secondary flange body <NUM> may additionally be positioned in contact with other portions of the primary flange body <NUM> such as, for example, the distal end <NUM>. The secondary flange body <NUM> defines a plurality of circumferentially-spaced secondary bolt apertures <NUM> extending through the primary flange body <NUM> from the first secondary surface <NUM> to the second secondary surface <NUM>. Each secondary bolt aperture <NUM> of the plurality of secondary bolt apertures <NUM> is aligned with a respective one of the plurality of primary bolt apertures <NUM>.

The flange assembly <NUM> includes a plurality of bolts <NUM> or other fasteners configured to couple the primary flange <NUM> and the secondary flange <NUM>. Each bolt <NUM> includes a bolt body <NUM> extending between a head end <NUM> and a distal end <NUM> along a bolt axis <NUM> (e.g., a center axis of the bolt <NUM>). The bolt body <NUM> includes an annular surface <NUM> located between the head end <NUM> and the distal end <NUM>. The annular surface <NUM> is disposed about the bolt axis <NUM>. The bolt body <NUM> of each bolt <NUM> is positioned within respective ones of the plurality of primary bolt apertures <NUM> and the plurality of secondary bolt apertures <NUM>. Each bolt <NUM> further includes a nut <NUM> detachably mounted (e.g., threadably mounted) to the bolt body <NUM> such that the primary flange <NUM> and the secondary flange <NUM> are positioned between the head end <NUM> and the nut <NUM> with the head end <NUM> adjacent the primary flange <NUM> and the nut <NUM> adjacent the secondary flange <NUM>. In some embodiments, the bolt <NUM> may include an annular washer <NUM> positioned between the nut <NUM> and the secondary flange <NUM>.

Referring again to <FIG>, during assembly of the flange assembly <NUM>, the plurality of bolts <NUM> may be installed in the respective plurality of primary bolt apertures <NUM> of the primary flange <NUM>. The plurality of bolts <NUM> of <FIG> may be installed, for example, in a forward axial direction with respect to the longitudinal centerline <NUM>. With the plurality of bolts <NUM> installed in the primary flange <NUM>, the low-pressure compressor module <NUM> may be installed. The secondary flange <NUM> of the low-pressure compressor module <NUM> may be installed into the flange assembly <NUM> such that the plurality of bolts <NUM> are positioned in the respective plurality of secondary bolt apertures <NUM> of the secondary flange <NUM>. The secondary flange <NUM> of <FIG> may be installed, for example, in an aft axial direction with respect to the longitudinal centerline <NUM>. In other words, the secondary flange <NUM> may be installed in a direction in opposition to the direction of installation for the plurality of bolts <NUM>.

Once the secondary flange <NUM> has been installed on the flange assembly <NUM>, a portion of the compressor section <NUM> may become physically inaccessible to operators performing the assembly process due to physical obstruction by the secondary flange <NUM> and the low-pressure compressor module <NUM>. The inaccessible portion of the compressor section <NUM> is identified in <FIG> as the inaccessible side <NUM> of the flange assembly <NUM>. An opposing side of the flange assembly <NUM> remains physically accessible to the operators performing the assembly process and is identified in <FIG> as the accessible side <NUM> of the flange assembly <NUM>. As shown in <FIG>, the head end <NUM> of each bolt body <NUM> is positioned within the inaccessible side <NUM> and physical access to the head end <NUM> of each bolt body <NUM> may not be possible without removal of the secondary flange <NUM>.

Installation of the low-pressure compressor module <NUM>, including the secondary flange <NUM>, as well as subsequent assembly steps for the gas turbine engine <NUM>, presents a risk of causing one or more of the plurality of bolts <NUM> to become dislodged from the flange assembly <NUM> and to fall into the inaccessible side <NUM>. Dislodging of bolts <NUM> can occur, for example, as a result of collisions while installing the low-pressure compressor module <NUM>, positioning torquing tools (e.g., a torque measuring system (TMS)), or while torquing or untorquing the nuts <NUM> of the respective bolts <NUM>. Any bolts <NUM> which become dislodged from the flange assembly <NUM> must be recovered, which may require removal of the low-pressure compressor module <NUM> and/or other components of the gas turbine engine <NUM>. While aspects of the present disclosure are described herein with respect to an exemplary mating interface between the low-pressure compressor <NUM> and the low-pressure shaft <NUM>, aspects of the present disclosure flange assembly <NUM> are applicable for any blind assemblies in which a fastener, such as a bolt, may have one side (e.g., a head of the bolt) that is inaccessible during a portion of an assembly sequence. Accordingly, the present disclosure should not be understood to be limited to compressors such as the low-pressure compressor <NUM>, turbofan gas turbine engines, such as the gas turbine engine <NUM>, or even gas turbines engines in general, and may be relevant in the assembly of other forms of machinery and industrial equipment as well.

Referring to <FIG>, side cross-sectional views of embodiments of the flange assembly <NUM> are illustrated including a bolt <NUM> of the plurality of bolts <NUM> installed in respective ones of the plurality of primary bolt apertures <NUM> and the plurality of secondary bolt apertures <NUM>. The bolt <NUM> includes an annular groove <NUM> formed in the annular surface <NUM> of the bolt body <NUM> and disposed about the bolt axis <NUM>. The flange assembly <NUM> further includes a clip <NUM> attached to the bolt body <NUM> within the annular groove <NUM>. In other words, the clip <NUM> is seated within the annular groove <NUM>. The clip <NUM> is positioned between the primary flange <NUM> and the secondary flange <NUM>. The clip <NUM> may be configured as a C-clip (sometimes known as a "circlip") which may be formed by a semi-rigid ring with open ends which can be snapped into place about the bolt axis <NUM> within the annular groove <NUM>. As shown in <FIG>, the clip <NUM> includes a first radial portion 102A positioned radially within the annular groove <NUM> and a second radial portion 102B positioned radially outside the annular groove <NUM>, with respect to the bolt axis <NUM>. Accordingly, any dislodging force (e.g., an axial force) applied to the bolt <NUM> may cause the clip <NUM> to contact the second primary surface <NUM> of the primary flange body <NUM> of the primary flange <NUM>, thereby potentially preventing the bolt <NUM> from being dislodged from the flange assembly <NUM>. However, in some cases, more significant dislodging forces may be capable of unseating the clip <NUM> from the annular groove <NUM>, thereby allowing the bolt <NUM> to become dislodged from the flange assembly <NUM>.

The secondary flange body <NUM> may include an annular recess <NUM> formed between the secondary bolt aperture <NUM> and the first secondary surface <NUM>. The clip <NUM> may be axially retained within the annular recess <NUM>, with respect to the bolt axis <NUM>. With the clip <NUM> positioned within the annular groove <NUM> of the bolt body <NUM>, the secondary flange body <NUM> may be radially spaced from the clip <NUM>, with respect to the bolt axis <NUM>, at the location of the annular recess <NUM>.

Referring to <FIG>, in some embodiments, the primary flange body <NUM> may include an annular chamfer <NUM> extending from the primary bolt aperture <NUM> to the second primary surface <NUM>. The annular chamfer <NUM> is disposed about the bolt axis <NUM>. The annular chamfer <NUM> is positioned axially adjacent the clip <NUM>, with respect to the bolt axis <NUM>. The annular chamfer <NUM> includes a chamfer surface <NUM> which extends between an inner radial chamfer end <NUM> and an outer radial chamfer end <NUM>, with respect to the bolt axis <NUM>. The chamfer surface <NUM> of <FIG> and <FIG> is flat (e.g., linear) or substantially flat in a direction extending between the inner radial chamfer end <NUM> and the outer radial chamfer end <NUM>. As will be discussed in further detail, an axial dislodging force (schematically illustrated in <FIG> as force <NUM>), with respect to the bolt axis <NUM>, applied to the bolt <NUM> may cause the clip <NUM> to contact the chamfer surface <NUM> of the annular chamfer <NUM>. Thus, the chamfer surface <NUM> may apply a radial retention force (schematically illustrated in <FIG> as force <NUM>), with respect to the bolt axis <NUM>, to the clip <NUM> which pushes the clip <NUM> in the direction of the annular groove <NUM>, thereby preventing or otherwise opposing the clip <NUM> from being unseated from the annular groove <NUM> by the axial dislodging force <NUM>.

<FIG> illustrates the clip <NUM> in contact with the chamfer surface <NUM> of the annular chamfer <NUM> of <FIG>. The annular groove <NUM> has a height h extending between a bottom of the annular groove <NUM> and the annular surface <NUM> of the bolt body <NUM>. As shown in <FIG>, the clip <NUM> has a circular or substantially circular cross-sectional shape with a cross-sectional radius r. The height h of the annular groove <NUM> is illustrated in <FIG> as being less than the cross-sectional radius r. However, the present disclosure is not limited to this particular relationship between the height h and the cross-sectional radius r. , and the height h may alternatively be greater than or equal to the cross-sectional radius r. A chamfer angle Θ is defined between the chamfer surface <NUM> (e.g., from the inner radial chamfer end <NUM> to the outer radial chamfer end <NUM>) and an axial line <NUM> which is parallel to the bolt axis <NUM>. As shown in <FIG>, the chamfer angle Θ of the chamfer surface <NUM> may be approximately forty-five degrees (<NUM>°). A minimum value of the chamfer angle Θ may be determined, for example, using Equation [<NUM>]: <MAT> The chamfer angle Θ may preferably be between twenty degrees (<NUM>°) and sixty degrees (<NUM>°) or between thirty degrees (<NUM>°) and fifty degrees (<NUM>°). A chamfer angle may also be measured relative to a radial line, and may be between <NUM> and <NUM> degrees.

Referring to <FIG>, in some embodiments, the chamfer surface <NUM> may be curved in a direction extending between the inner radial chamfer end <NUM> and the outer radial chamfer end <NUM>. The chamfer surface <NUM> of <FIG> is convex between the inner radial chamfer end <NUM> and the outer radial chamfer end <NUM>. The chamfer surface <NUM> of <FIG> is concave between the inner radial chamfer end <NUM> and the outer radial chamfer end <NUM>. In some embodiments, the chamfer surface <NUM> may have a concave curvature which substantially matches the cross-sectional curvature of the clip <NUM>.

Referring to <FIG>, in some embodiments, in clip <NUM> includes a cross-sectional flat surface <NUM>. The cross-sectional flat surface <NUM> extends in a circumferential direction about the clip <NUM>. The cross-sectional flat surface <NUM> is positioned on the clip <NUM> such that an axial withdrawal of the bolt <NUM> from the flange assembly <NUM> along the bolt axis <NUM> will cause the cross-sectional flat surface <NUM> to contact the chamfer surface <NUM> of the annular chamfer <NUM>. In some embodiments, the cross-sectional flat surface <NUM> of the clip <NUM> may be substantially parallel to the chamfer surface <NUM> of the annular chamfer <NUM> of the primary flange body <NUM>. As used herein, the term "substantially" with respect to a direction or angular relationship refers to the stated direction or angular relationship +/- five degrees (<NUM>°).

Referring to <FIG>, in some embodiments, the primary flange body <NUM> may include an annular recess <NUM> extending from the primary bolt aperture <NUM> to the second primary surface <NUM>. The annular recess <NUM> is disposed about the bolt axis <NUM>. The annular recess <NUM> is positioned axially adjacent the clip <NUM>, with respect to the bolt axis <NUM>. As shown in <FIG>, the annular recess <NUM> may have a substantially rectangular cross-sectional shape. In some embodiments, the annular recess <NUM> may include an axially-extending surface <NUM> and a radially-extending surface <NUM> which intersects the axially-extending surface <NUM>. The axially-extending surface <NUM> may be spaced (e.g., radially spaced) from the annular surface <NUM> of the bolt body <NUM> by a distance D1. The distance D1 may be less than a cross-sectional diameter D2 of the clip <NUM>. Accordingly, if the clip <NUM> is axially positioned within the annular recess <NUM>, the axially-extending surface <NUM> may prevent (e.g., physically obstruct) the clip <NUM> from being unseated from the annular groove <NUM> of the bolt body <NUM>.

Referring to <FIG>, in some embodiments, the secondary flange body <NUM> includes an axially-extending surface <NUM> which defines a portion of the annular recess <NUM>. The axially-extending surface <NUM> may be spaced (e.g., radially spaced) from the annular surface <NUM> of the bolt body <NUM> by a distance D3. The distance D3 may be less than the cross-sectional diameter D2 of the clip <NUM>. Accordingly, with the clip <NUM> axially positioned within the annular recess <NUM>, the axially-extending surface <NUM> may prevent (e.g., physically obstruct) the clip <NUM> from being unseated from the annular groove <NUM> of the bolt body <NUM>.

Referring to <FIG>, in some embodiments, the flange assembly <NUM> may include a washer <NUM> disposed about the bolt body <NUM> and positioned between the primary flange <NUM> and the secondary flange <NUM>. The washer <NUM> may be positioned axially within the recess <NUM> of the secondary flange body <NUM>. As shown in <FIG>, the washer <NUM> may be positioned radially outside of the clip <NUM>, with respect to the bolt axis <NUM>. Accordingly, the washer <NUM> may prevent (e.g., physically obstruct) the clip <NUM> from being unseated from the annular groove <NUM> of the bolt body <NUM>.

Referring to <FIG>, in some embodiments, the primary flange body <NUM> may include an annular projection <NUM>. The annular projection <NUM> may extend axially from the second primary surface <NUM> toward the secondary flange body <NUM>, with respect to the bolt axis <NUM>. The annular projection <NUM> may be positioned within the annular recess <NUM> of the secondary flange body <NUM>. As shown in <FIG>, the annular projection <NUM> may be positioned radially outside of the clip <NUM>, with respect to the bolt axis <NUM>. Accordingly, the annular projection <NUM> may prevent (e.g., physically obstruct) the clip <NUM> from being unseated from the annular groove <NUM> of the bolt body <NUM>. In some embodiments, the annular projection <NUM> may be formed as a unitary structure with the primary flange body <NUM>. The term "unitary structure," as used herein, means a single component, wherein the primary flange body <NUM> and the annular projection <NUM> are an inseparable body (e.g., formed of a single material, or a weldment of independent elements, etc.). A unitary structure of the primary flange body <NUM> and the annular projection <NUM> may decrease the potential for foreign object damage ("FOD") to the gas turbine engine <NUM>.

It is noted that various connections are set forth between elements in the preceding description and in the drawings. It is noted that these connections are general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect. A coupling between two or more entities may refer to a direct connection or an indirect connection. An indirect connection may incorporate one or more intervening entities. It is further noted that various method or process steps for embodiments of the present disclosure are described in the following description and drawings. The description may present the method and/or process steps as a particular sequence. However, to the extent that the method or process does not rely on the particular order of steps set forth herein, the method or process should not be limited to the particular sequence of steps described. As one of ordinary skill in the art would appreciate, other sequences of steps may be possible. Therefore, the particular order of the steps set forth in the description should not be construed as a limitation.

As used herein, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Claim 1:
A flange assembly (<NUM>) comprising:
a primary flange (<NUM>) including a primary flange body (<NUM>), the primary flange body (<NUM>) including a first primary surface (<NUM>) and a second primary surface (<NUM>) opposite the first primary surface (<NUM>), the primary flange body (<NUM>) defining a primary bolt aperture (<NUM>) extending from the first primary surface (<NUM>) to the second primary surface (<NUM>);
a secondary flange (<NUM>) positioned adjacent the primary flange (<NUM>), the secondary flange (<NUM>) including a secondary flange body (<NUM>), the secondary flange body (<NUM>) including a first secondary surface (<NUM>) and a second secondary surface (<NUM>) opposite the first secondary surface (<NUM>), the secondary flange body (<NUM>) defining a secondary bolt aperture (<NUM>) extending from the first secondary surface (<NUM>) to the second secondary surface (<NUM>);
a bolt (<NUM>) including a bolt body (<NUM>) extending between a head end (<NUM>) and a distal end (<NUM>) along a bolt axis (<NUM>), the bolt body (<NUM>) including an annular surface (<NUM>) disposed about the bolt axis (<NUM>), the bolt body (<NUM>) positioned within the primary bolt aperture (<NUM>) and the secondary bolt aperture (<NUM>), the bolt (<NUM>) further including a nut (<NUM>) detachably mounted to the bolt body (<NUM>) such that the primary flange (<NUM>) and the secondary flange (<NUM>) are positioned between the head end (<NUM>) and the nut (<NUM>) with the head end (<NUM>) adjacent the primary flange (<NUM>); characterized in:
the bolt body (<NUM>) further including an annular groove (<NUM>) formed in the annular surface (<NUM>) and disposed about the bolt axis (<NUM>), and having a clip (<NUM>) attached to the bolt body (<NUM>) within the annular groove (<NUM>), the clip (<NUM>) positioned between the primary flange (<NUM>) and the secondary flange (<NUM>)