Sealing test device and method for underwater device shell of outboard diesel engine

Abstract

The invention discloses a sealing test device and method for an outboard diesel engine underwater device shell, and belongs to the technical field of sealing test auxiliary tools. The sealing part is matched with a propeller shaft mounting hole of an underwater device shell, the front end of the operation part is connected with the sealing part, and the rear end of the operation part can be in threaded connection with a threaded hole of the underwater device shell; the sealing part comprises a sealing ring seat, an O-shaped sealing ring and a thrust pad, the rear end of the sealing ring seat is connected with the operation part, the O-shaped sealing ring and the thrust pad are sequentially arranged at the front end of the sealing ring seat in a sleeving mode, and the thrust pad can move in the axial direction of the sealing ring seat. The front end of the thrust pad abuts against a flange at the position of an opening in the front side of the propeller shaft installation hole, and the rear end of the thrust pad is matched with the sealing ring base to axially compress the O-shaped sealing ring so that the O-shaped sealing ring can expand in the radial direction to seal the propeller shaft installation hole. Therefore, the O-shaped sealing ring can be repeatedly used in the test process.

Description

Technical Field

[0001] The present invention belongs to the technical field of sealing test auxiliary tools, and particularly relates to a sealing test device and method for the housing of an outboard diesel engine underwater device. Background Art

[0002] As shown in Figure 1 , a propeller shaft mounting hole 2 is formed inside a housing 1 of an existing outboard diesel engine underwater device, and a threaded hole 4 communicating with the propeller shaft mounting hole 2 and provided with internal threads is arranged at the rear side of the propeller shaft mounting hole 2. Due to installation requirements, a flange 2-1 is circumferentially arranged at the front side orifice of the propeller shaft mounting hole 2 far from the threaded hole 4, and an uneven portion 3 is present above the orifice at the rear side of the propeller shaft mounting hole 2 close to the threaded hole 4. The edge of the uneven portion 3 is sharp and has burrs, and chamfering cannot be performed here to make it smooth and round. Generally, the propeller shaft mounting hole 2 needs to be sealed with an O-ring. After the housing 1 of the underwater device is processed, a sealing test needs to be carried out first. Therefore, the O-ring will be reused repeatedly. However, when a conventional O-ring is used for the sealing test, the O-ring is extremely easy to be cut and damaged by the edge of the uneven portion 3 during the installation process, resulting in the inability to carry out the sealing test of the housing 1 of the underwater device.

[0003] Therefore, there is a need for a sealing test device and method for the housing of an outboard diesel engine underwater device that can effectively avoid damage to the O-ring during the sealing test. Summary of the Invention

[0004] The purpose of the present invention is to provide a sealing test device and method for the housing of an outboard diesel engine underwater device, which can effectively avoid damage to the O-ring during the sealing test, enable the O-ring to be reused repeatedly during the test, and ensure the smooth progress of the sealing test of the housing of the underwater device.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is: A sealing test device for the housing of an outboard diesel engine underwater device includes a sealing part adapted to the propeller shaft mounting hole of the housing of the underwater device and an operating part connected to the front end of the sealing part and threadedly connectable to the threaded hole of the housing of the underwater device at the rear end; the sealing part includes a sealing ring seat connected to the operating part at the rear end, an O-ring sleeved on the front end of the sealing ring seat in sequence, and a thrust pad movable axially along the sealing ring seat. When the operating part is threadedly connected to the threaded hole and axially pushes the sealing ring seat forward, the front end of the thrust pad abuts against the flange at the front side orifice of the propeller shaft mounting hole, and the rear end thereof cooperates with the sealing ring seat to axially compress the O-ring to radially expand it to seal the propeller shaft mounting hole.

[0006] A further improvement of the technical solution of the present invention lies in that: on the front end face of the seal ring seat, a stepped assembly groove without an outer wall is circumferentially formed along its outer periphery. The assembly groove includes a thrust pad assembly groove for loading a thrust pad circumferentially formed along the outer periphery of the front end face of the seal ring seat, and a seal ring assembly groove for loading an O-ring circumferentially formed along the outer periphery of the bottom of the thrust pad assembly groove. And the bottom of the seal ring assembly groove is a pressure-bearing surface inclined backward.

[0007] A further improvement of the technical solution of the present invention lies in that: at the center of the front end face of the seal ring seat, a retaining ring for limiting the thrust pad in the thrust pad assembly groove is provided by a screw.

[0008] A further improvement of the technical solution of the present invention lies in that: the thrust pad is of an annular structure. On its front end face, a card slot without an outer wall adapted to the flange at the front side hole of the propeller shaft mounting hole is circumferentially formed along its outer periphery. On its rear end face, a positioning groove without an inner wall is circumferentially formed along its inner periphery. And a pushing boss adapted to the seal ring assembly groove of the seal ring seat is formed on the outer periphery of the positioning groove.

[0009] A further improvement of the technical solution of the present invention lies in that: there is a clearance fit between the pushing boss of the thrust pad and the inner side wall of the seal ring assembly groove of the seal ring seat.

[0010] A further improvement of the technical solution of the present invention lies in that: the depth of the thrust pad assembly groove of the seal ring seat is greater than the thickness of the thrust pad.

[0011] A further improvement of the technical solution of the present invention lies in that: the operating part includes a handle with its front end connected to the seal ring seat and a threaded baffle movably sleeved on the rear end of the handle and threadedly connectable to the threaded hole.

[0012] A further improvement of the technical solution of the present invention lies in that: the handle is of a stepped column structure. Its front end is a stop end connected to the seal ring seat, and its rear end is a holding end with a diameter smaller than that of the stop end. The threaded baffle is sleeved on the holding end of the handle.

[0013] A further improvement of the technical solution of the present invention lies in that: the threaded baffle is of an annular plate-like structure with an external thread on its outer edge, and a plurality of mounting holes are formed in the threaded baffle along its thickness direction.

[0014] A method for sealing test of the housing of an outboard diesel engine underwater device, using a sealing test device for the sealing test, includes the following steps: Step S1: Device installation: Insert the sealing part of the sealing test device into the propeller shaft mounting hole of the underwater device housing, so that the threaded baffle on the handle of its operating part is aligned with the threaded hole on the underwater device housing; Step S2: Pre-tightening of the operating part: Screw the threaded baffle so that it is threadedly connected to the threaded hole. During the screwing process, the stop end of the handle is used to push the seal ring seat to move axially forward, so that the card slot at the front end of the thrust pad is initially abutted against the flange at the front side orifice of the propeller shaft mounting hole; Step S3: Compression of the seal ring: As the seal ring seat moves forward, there is a clearance fit between the pushing boss at the rear end of the thrust pad and the inner side wall of the seal ring assembly groove of the seal ring seat, so that the pushing boss at the rear end of the thrust pad and the axially forward moving seal ring seat cooperate to axially compress the O-ring in its seal ring assembly groove towards the pressure bearing surface until the O-ring expands radially and closely adheres to the inner wall of the propeller shaft mounting hole; Step S4: Sealing performance verification: Fill the inside of the underwater device housing with a test medium and pressurize it to detect the leakage between the propeller shaft mounting hole and the seal test device. If it is unqualified, repeat steps S1 - S3.

[0015] Due to the adoption of the above technical solution, the technical progress achieved by the present invention is: The present invention relates to a seal test device and method for the housing of an outboard diesel engine underwater device. Through the dual protection mechanisms of physical isolation between the thrust pad and the seal ring seat and axial compression sealing, it fundamentally avoids the contact between the O-ring and the uneven part above the rear orifice of the propeller shaft mounting hole. At the same time, stable sealing is achieved through controllable screw drive, which can effectively avoid damage to the O-ring during the sealing performance test, enabling the O-ring to be reused repeatedly during the test and ensuring the smooth progress of the sealing performance test of the underwater device housing.

[0016] During the installation process of the present invention, when the operating part is screwed into the threaded hole of the underwater device housing, the O-ring is restricted in the front safety area between the thrust pad and the seal ring seat, that is, in the seal ring assembly groove. Protected by the thrust pad and the seal ring seat, it avoids contact between the O-ring and the uneven part above the rear orifice of the propeller shaft mounting hole, thus effectively avoiding damage to the O-ring by the sharp edges or burrs of the uneven part during the sealing performance test.

[0017] During the test process of the present invention, the operating part is used to push the seal ring seat forward by being threadedly connected to the threaded hole of the underwater device housing, so that the front end of the thrust pad abuts against the flange at the front side orifice of the propeller shaft mounting hole, causing the O-ring to be axially compressed between the seal ring seat and the thrust pad. Since the compression direction of the O-ring is axial rather than radial, its deformation only occurs on the circumferential surface in contact with the hole wall of the propeller shaft mounting hole, without having to slide over the uneven part above the rear orifice of the propeller shaft mounting hole, thus further effectively avoiding damage to the O-ring during the sealing performance test and enabling the O-ring to be reused repeatedly during the test. Description of the Drawings

[0018] Figure 1 is a schematic structural view of the underwater device housing of the outboard diesel engine in the background art of the present invention; Figure 2 is a schematic structural view of the sealing test device of the present invention; Figure 3 is an assembly schematic view of the sealing test device and the underwater device housing of the present invention; Figure 4 is a schematic view of the sealing ring in the sealing test device of the present invention before being extruded; Figure 5 is a schematic view of the sealing ring in the sealing test device of the present invention after being extruded; Among them, 1. underwater device housing, 2. propeller shaft mounting hole, 2-1. flange, 3. uneven part, 4. threaded hole, 5. screw, 6. retaining ring, 7. thrust pad, 7-1. clamping groove, 7-2. positioning groove, 7-3. pushing boss, 8. O-ring, 9. sealing ring seat, 9-1. bearing surface, 10. handle, 11. threaded baffle. Specific Embodiment

[0019] The present invention will be further described in detail below with reference to the embodiments: Embodiment 1 As Figure 2 and Figure 3 shown, this embodiment provides a sealing test device for the underwater device housing of an outboard diesel engine, including a sealing part and an operating part. The sealing part is adapted to the propeller shaft mounting hole 2 of the underwater device housing 1, and the front end of the operating part is connected to the sealing part, and the rear end of the operating part can be threadedly connected to the threaded hole 4 of the underwater device housing 1. Specifically, the sealing part includes a sealing ring seat 9, a thrust pad 7, and an O-ring 8. Among them, the rear end of the sealing ring seat 9 is connected to the operating part, and the O-ring 8 and the thrust pad 7 are sequentially sleeved on the front end of the sealing ring seat 9, that is, the O-ring 8 is located between the thrust pad 7 and the sealing ring seat 9, and the thrust pad 7 is adapted to the flange 2-1 at the front side hole of the propeller shaft mounting hole 2 and can move axially along the sealing ring seat 9 to axially compress the O-ring 8 in cooperation with the sealing ring seat 9. As Figure 5 shown, when the operating part is threadedly connected to the threaded hole 4 of the underwater device housing 1, during the threaded connection process, the operating part can axially push the sealing ring seat 9 forward, so that the front end of the thrust pad 7 abuts against the flange 2-1 at the front side hole of the propeller shaft mounting hole 2, and its rear end axially compresses the O-ring 8 in cooperation with the sealing ring seat 9, causing the O-ring 8 to expand radially, thereby sealing the propeller shaft mounting hole 2. It should be noted that as Figure 4As shown in the figure, before the O-ring 8 is axially compressed, that is, before the front end of the thrust pad 7 abuts against the flange 2-1 at the front side orifice of the propeller shaft mounting hole 2, the thrust pad 7 and the seal ring seat 9 do not generate an axial compression force on the O-ring 8. At this time, the O-ring 8 does not undergo radial expansion deformation, and its outer diameter size is slightly smaller than the inner diameter size of the propeller shaft mounting hole 2. Therefore, it effectively avoids the O-ring 8 directly contacting the uneven portion 3 above the rear side orifice of the propeller shaft mounting hole 2 during the installation process.

[0020] Under the dual protection mechanism of physical isolation and axial compression sealing between the thrust pad 7 and the seal ring seat 9, the present invention fundamentally avoids the contact between the O-ring 8 and the uneven portion 3 above the rear side orifice of the propeller shaft mounting hole 2. At the same time, stable sealing is achieved through controllable screw drive, which can effectively avoid damage to the O-ring 8 during the sealing performance test, enabling the O-ring 8 to be reused repeatedly during the test and ensuring the smooth progress of the sealing performance test of the underwater device housing 1.

[0021] Furthermore, a stepped outer-wallless assembly groove is circumferentially formed along the outer periphery of the front end face of the seal ring seat 9. The assembly groove includes a thrust pad assembly groove for loading the thrust pad 7 without an outer wall and a seal ring assembly groove for loading the O-ring 8 without an outer wall. Specifically, the thrust pad assembly groove is circumferentially formed along the outer periphery of the front end face of the seal ring seat 9, so that a guide post is formed at the center of the front end face of the seal ring seat 9. The thrust pad 7 is located in the thrust pad assembly groove and can axially move along the guide post. The seal ring assembly groove is circumferentially formed along the outer periphery of the bottom of the thrust pad assembly groove, that is, the seal ring assembly groove is located behind the thrust pad assembly groove and on its radial outer side. The O-ring 8 is located in the seal ring assembly groove, and the bottom of the seal ring assembly groove is a pressure-bearing surface 9-1 inclined backward, with an inclination angle between 30° and 45°. Among them, the outer-wallless thrust pad assembly groove and the outer-wallless seal ring assembly groove both refer to grooves with only inner walls, no outer walls, and communicating with the space on the radial outer side, and the cross-section is in the shape of an "L".

[0022] In order to limit the thrust pad 7 in the thrust pad assembly groove and prevent the thrust pad 7 from falling off the thrust pad assembly groove, a retaining ring 6 is provided on the guide post at the center of the front end face of the seal ring seat 9 through a screw 5.

[0023] Further, the thrust pad 7 is of an annular structure. An outer wall-less card slot 7-1 is circumferentially formed on the front end face of the thrust pad 7 along its outer circumference. The card slot 7-1 is adapted to the flange 2-1 at the front side orifice of the propeller shaft mounting hole 2 and can be abutted and engaged with the flange 2-1. An inner wall-less positioning groove 7-2 is circumferentially formed on the rear end face of the thrust pad 7 along its inner circumference. And an annular pushing boss 7-3 adapted to the seal ring assembly groove of the seal ring seat 9 is formed on the outer circumference of the positioning groove 7-2. Preferably, the positioning groove 7-2 is a stepped groove. Among them, the outer wall-less card slot 7-1 refers to a groove with only an inner side wall, no outer side wall, and a cross-section of "L" shape communicating with the space on the radial outer side. The inner wall-less positioning groove 7-2 refers to a groove with only an outer side wall, no inner side wall, and communicating with the space on the radial inner side.

[0024] Specifically, a clearance fit is provided between the pushing boss 7-3 of the thrust pad 7 and the inner side wall of the seal ring assembly groove of the seal ring seat 9, so as to ensure that the pushing boss 7-3 of the thrust pad 7 can move within the seal ring assembly groove of the seal ring seat 9.

[0025] When the operating part is threadedly connected to the threaded hole 4 of the underwater device housing 1 and axially pushes the seal ring seat 9 forward, the card slot 7-1 at the front end of the thrust pad 7 abuts against the flange 2-1 at the front side orifice of the propeller shaft mounting hole 2. As the seal ring seat 9 moves forward, the pushing boss 7-3 at the rear end of the thrust pad 7 cooperates with the axially forward moving seal ring seat 9 to axially compress the O-ring 8 within its seal ring assembly groove, causing the O-ring 8 to radially expand on the pressure bearing surface 9-1 of the seal ring assembly groove.

[0026] To ensure that the thrust pad 7 has a certain moving space on the seal ring seat 9, the depth of the thrust pad assembly groove of the seal ring seat 9 is slightly greater than the thickness of the thrust pad 7.

[0027] Further, the operating part includes a handle 10 and a threaded baffle 11 that can be threadedly connected to the threaded hole 4. The front end of the handle 10 is connected to the seal ring seat 9. The threaded baffle 11 is movably sleeved on the rear end of the handle 10, that is, the threaded baffle 11 can rotate relative to the handle 10 and is movably sleeved thereon. When the threaded baffle 11 rotates, the handle 10 does not rotate and move therewith. Specifically, the handle 10 is of a stepped column structure. Its front end is a stop end connected to the seal ring seat 9, and its rear end is a holding end with a diameter smaller than that of the stop end. The threaded baffle 11 is sleeved on the holding end of the handle 10. The threaded baffle 11 is of an annular plate-like structure with an external thread on its outer edge. The threaded baffle 11 is provided with a plurality of mounting holes along its thickness direction for connection with mounting tools. During installation, by screwing the threaded baffle 11 to be threadedly connected to the threaded hole 4, during the screwing process, the threaded baffle 11 can axially push the seal ring seat 9 forward through the stop end of the handle 10.

[0028] Embodiment 2 This embodiment provides a sealing test method for the housing of an outboard diesel engine underwater device. The sealing test is carried out using the sealing test device of Embodiment 1, and includes the following steps: Step S1: Device installation: Insert the sealing part of the sealing test device into the propeller shaft installation hole 2 of the underwater device housing 1, and align the threaded baffle 11 on the handle 10 of its operating part with the threaded hole 4 on the underwater device housing 1. At this time, the O-ring 8 is restricted in the front safety area between the thrust pad 7 and the seal ring seat 9, that is, the seal ring assembly groove. Protected by the thrust pad 7 and the seal ring seat 9, the O-ring 8 is prevented from contacting the uneven part 3 above the rear orifice of the propeller shaft installation hole 2, thus effectively avoiding damage to the O-ring 8 by the sharp edges or burrs of the uneven part 3 during the sealing test; Step S2: Pre-tightening of the operating part: Thread the threaded baffle 11 with the threaded hole 4 by screwing it. During the screwing process, push the seal ring seat 9 axially forward through the stop end of the handle 10, so that the card slot 7-1 at the front end of the thrust pad 7 initially abuts against the flange 2-1 at the front orifice of the propeller shaft installation hole 2; Step S3: Seal ring compression: As the seal ring seat 9 moves forward, there is a clearance fit between the thrust boss 7-3 at the rear end of the thrust pad 7 and the inner wall of the seal ring assembly groove of the seal ring seat 9, so that the thrust boss 7-3 at the rear end of the thrust pad 7 and the axially forward moving seal ring seat 9 cooperate to axially compress the O-ring 8 in its seal ring assembly groove towards the bearing surface 9-1 of the seal ring assembly groove until the O-ring 8 expands radially and tightly adheres to the inner wall of the propeller shaft installation hole 2. During this process, the O-ring 8 is axially compressed between the seal ring seat 9 and the thrust pad 7. Since the compression direction of the O-ring 8 is axial rather than radial, its deformation only occurs on the circumferential surface in contact with the hole wall of the propeller shaft installation hole 2, without sliding over the uneven part 3 above the rear orifice of the propeller shaft installation hole 2, thus further effectively avoiding damage to the O-ring 8 during the sealing test and enabling the O-ring 8 to be reused repeatedly during the test; Step S4: Sealing verification: Fill the inside of the underwater device housing 1 with the test medium and pressurize it, and detect the leakage between the propeller shaft installation hole 2 and the sealing test device. If it is unqualified, repeat steps S1 - S3.

[0029] It is understood that the present invention is described by way of some embodiments. Those skilled in the art will appreciate that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the present invention. Additionally, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application belong to the scope protected by the present invention.

Claims

1. A sealing test device for the housing of an outboard diesel engine underwater device, characterized in that: It includes a sealing part adapted to the propeller shaft mounting hole (2) of the underwater device housing (1), and an operating part with its front end connected to the sealing part and its rear end threadedly connectable to the threaded hole (4) of the underwater device housing (1); the sealing part includes a sealing ring seat (9) with its rear end connected to the operating part, an O-ring (8) sleeved on the front end of the sealing ring seat (9) in sequence, and a thrust pad (7) movable along the axial direction of the sealing ring seat (9). When the operating part is threadedly connected to the threaded hole (4) and axially pushes the sealing ring seat (9) forward, the front end of the thrust pad (7) abuts against the flange (2-1) at the front side orifice of the propeller shaft mounting hole (2), and its rear end cooperates with the sealing ring seat (9) to axially compress the O-ring (8) to make it radially expand and seal the propeller shaft mounting hole (2).

2. The sealing test device for the underwater device housing of an outboard diesel engine according to claim 1, characterized in that: On the front end face of the sealing ring seat (9), a stepped outer-wall-free assembly groove is circumferentially formed along its outer periphery. This assembly groove includes a thrust pad assembly groove for loading the thrust pad (7) circumferentially formed along the outer periphery of the front end face of the sealing ring seat (9), and a sealing ring assembly groove for loading the O-ring (8) circumferentially formed along the outer periphery of the bottom of the thrust pad assembly groove. And the bottom of the sealing ring assembly groove is a pressure-bearing surface (9-1) inclined backward.

3. The sealing test device for the underwater device housing of an outboard diesel engine according to claim 2, wherein: At the center of the front end face of the sealing ring seat (9), a retaining ring (6) for limiting the thrust pad (7) in the thrust pad assembly groove is provided by a screw (5).

4. A sealing test device for the housing of an outboard diesel engine underwater device according to claim 3, characterized in that: The thrust pad (7) is of an annular structure. Along its outer periphery on its front end face, a stepped outer-wall-free clamping groove (7-1) adapted to the flange (2-1) at the front side orifice of the propeller shaft mounting hole (2) is circumferentially formed. Along its inner periphery on its rear end face, a stepped inner-wall-free positioning groove (7-2) is circumferentially formed. And a pushing boss (7-3) adapted to the sealing ring assembly groove of the sealing ring seat (9) is formed on the outer periphery of the positioning groove (7-2).

5. A sealing test device for the housing of an outboard diesel engine underwater device according to claim 4, characterized in that: There is a clearance fit between the pushing boss (7-3) of the thrust pad (7) and the inner side wall of the sealing ring assembly groove of the sealing ring seat (9).

6. The sealing test device for the housing of an outboard diesel engine underwater device according to claim 5, characterized in that: The depth of the thrust pad assembly groove of the sealing ring seat (9) is greater than the thickness of the thrust pad (7).

7. A sealing test device for the housing of an outboard diesel engine underwater device according to any one of claims 1-6, characterized in that: The operating part includes a handle (10) with its front end connected to the sealing ring seat (9), and a threaded baffle (11) movably sleeved on the rear end of the handle (10) and threadedly connectable to the threaded hole (4).

8. A sealing test device for the housing of an outboard diesel engine underwater device according to claim 7, characterized in that: The handle (10) is of a stepped column structure. Its front end is a stop end connected to the sealing ring seat (9), and its rear end is a holding end with a diameter smaller than that of the stop end. The threaded baffle (11) is sleeved on the holding end of the handle (10).

9. A sealing test device for the housing of an outboard diesel engine underwater device according to claim 8, characterized in that: The threaded baffle (11) is of an annular plate-like structure with an external thread on its outer edge. The threaded baffle (11) is provided with a plurality of mounting holes along its thickness direction.

10. A sealing test method for the housing of an outboard diesel engine underwater device, characterized in that: Performing a sealing test using the sealing test device according to any one of claims 1-9, including the following steps: Step S1: Device installation: Insert the sealing part of the sealing test device into the propeller shaft mounting hole (2) of the underwater device housing (1) so that the threaded baffle (11) on the handle (10) of the operating part is aligned with the threaded hole (4) on the underwater device housing (1). Step S2: Pre-tightening of the operating part: By screwing the threaded baffle (11) to make it threadedly connected to the threaded hole (4), and during the screwing process, the stop end of the handle (10) is used to push the sealing ring seat (9) to move axially forward, so that the card slot (7-1) at the front end of the thrust pad (7) is initially abutted against the flange (2-1) at the front side orifice of the propeller shaft mounting hole (2); Step S3: Compression of the sealing ring: As the sealing ring seat (9) moves forward, the gap between the thrust boss (7-3) at the rear end of the thrust pad (7) and the inner wall of the sealing ring assembly groove of the sealing ring seat (9) is in clearance fit, so that the thrust boss (7-3) at the rear end of the thrust pad (7) and the axially forward moving sealing ring seat (9) cooperate to axially compress the O-ring (8) in its sealing ring assembly groove to deform towards the pressure bearing surface (9-1) until the O-ring (8) expands radially and closely adheres to the inner wall of the propeller shaft mounting hole (2); Step S4: Sealing performance verification: Fill the inside of the underwater device housing (1) with a test medium and pressurize it, and detect the leakage between the propeller shaft mounting hole (2) and the seal test device. If it is unqualified, repeat steps S1-S3.

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