Aircraft engine cowling roller attachment

Abstract: The aircraft cowling (20) is comprised of a cowling body (22), forward and aft bearings (24, 25) disposed on the cowling body (22) and corresponding sets of guides (29, 30) disposed on and conforming with the shape of the aircraft (26). The aft bearing (25) is comprised of two rollers (44) and two roller supports (46) which are disposed on the cowling body (22) in a manner permitting lateral motion and coupled by a shaft (50) with right-hand threads (56) on one end and left-hand threads (58) on the other end. The shaft (50), due to the opposing threads (56, 58), restricts the roller supports (46) to convergent and divergent movements and prevents movement in a common direction, thereby providing lateral support to the cowling (20) during opening and closing.

Description: Technical Field This invention relates to aircraft cowlings, and more particularly to attachment mechanisms for aircraft cowlings. Background Art Cowlings provide access to and protection for internal components of an aircraft. Aerodynamic considerations typically produce a cowling with a complex shape and require an attachment mechanism capable of withstanding significant air loads. An additional requirement of many aircraft applications is to design the cowling so as not to add significantly to the detectability of the aircraft. In order to do this, discontinuities in the fuselage should be kept to a minimum and whatever detectable parts are necessary for the attachment mechanism should be concealed if possible. A common technique of cowling attachment is to utilize a combination of hinge and latch assemblies. The drawback to this solution is that the complex shape of the cooling limits the hinges and latches to being positioned in remote locations relative to the loading on the cooling. The remote use requires the hinges and latches to be strengthened to supply the necessary reactive force and this strengthening typically adds weight, which is to be avoided for aircraft applications. Additionally, the external hinges and latches are exposed and produce discontinuities in the surface of the fuselage which are undesirable. Another solution is to utilize a sliding mechanism to attach the cowling to the aircraft. This typically involves having the edges of the cowling slide along guides built into the body of the aircraft, as disclosed in US-A-2,385,493 on which the two-part form of independent claim 1 is based. A major drawback to this solution is that the guides normally must be parallel and straight in order for the cowling to be able to slide. For aircraft applications, where aerodynamics is a concern, the complex body shapes make this solution impractical in many situations. Additionally, the guides are often exposed and are prone to jamming due to buildup of debris and ice. Disclosure of Invention An object of the invention includes the provision of a lightweight attachment mechanism for coupling two elements to permit relative motion between the elements while resisting applied loads in unison. Another object of the invention includes the provision of a lightweight attachment mechanism for opening and closing of an aircraft cowling. A still further object of the invention is provision of an attachment mechanism for an aircraft cowling which has minimal impact on detectability of the aircraft. According to the present invention there is provided an aircraft cowling attachment mechanism for attaching a cowling body to an aircraft, the cowling body being movable between an open and closed position and being shaped to conform to the aircraft in the closed position, wherein the attachment mechanism comprises forward and aft guides rigidly disposed on the aircraft; forward and aft bearings disposed in combination with the cowling body and engaged with said forward and aft guides, respectively, in a manner permitting translation of said forward and aft bearings along said respective forward and aft guides to move the cowling body generally parallel with the aircraft between the open and closed positions; characterized by two said aft guides having a convergent/divergent shape and being mirror images of each other with respect to the longitudinal centerline of the aircraft; said aft bearing including a channel for disposing said aft bearing in combination with the cowling body, a pair of roller supports engaged with said channel in a manner permitting convergent/divergent lateral motion of said roller supports with respect to the cowling body during movement thereof between the open and closed positions, and a pair of split spherical rollers rotatably mounted in combination with said roller supports and engaged with said aft guides in a manner permitting translation of said split spherical rollers along said aft guides to move the cowling body between the open and closed positions, said bearing further comprising a shaft having right-handed threads on one end thereof and left-handed threads on the other end thereof, and wherein each of said roller supports has a threaded aperture for rotatably coupling said threaded ends of said shaft with said pair of roller supports wherein rotation of said threaded ends of said shaft in said threaded apertures restricts said pair of roller supports to convergent/divergent lateral motion with respect to the cowling body during movement thereof between the open and closed positions. The relative motion of the aft bearing roller supports provides a reactive force to lateral loads during opening and closing of the cowling and permits the aft guides to be shaped to conform to the aircraft. In one embodiment, the split spherical rollers roll within cylindrical guides and the roller supports translate longitudinally within a slot along the underside of the guides. The position of the slot permits location of the guides under existing superstructure of the aircraft and therefore reduces the exposure of the guides. The slot also prevents the buildup of debris and ice in the guide which could degrade performance. Additionally, in the event of seizure of the rollers, the spherical shape of the rollers would enable the rollers to slide within the guides and permit removal of the cowling. Still further, the edges of the cowling and the aircraft can be shaped to provide lateral support when the cowling is closed with minimal discontinuity along the seam between the cowling and the aircraft. Additionally, a gasket type sealant can be disposed along the edge of the body to seal the internal cavity. The foregoing and other features and advantages of the present invention will become more apparent in light of the following detailed description of the exemplary embodiment thereof as illustrated in the accompanying drawings. Brief Description of Drawings FIG. 1 is a perspective view of an aircraft body and cowling. FIG. 2 is a side elevation view of an aircraft body with the location of the guides indicated. FIG. 3 is a top view of an aircraft body with the location of the guides indicated. FIG. 4 is a sectional, side elevation view of a cowling. FIG. 5 is a perspective view of an aft bearing. FIG. 6 is a perspective view of a guide, partially broken away and partially in section. FIG. 7 is a side view of a split spherical roller and guide, partially broken away and partially in section. FIG. 8 is a view taken along line 8-8 of FIG. 7, partially broken away and partially in section. FIG. 9 is a sectional view of a side cowling seam. FIG. 10 is a sectional view of an aft cowling seam. FIG. 11 is a side elevation view of a screw fastener assembly, partially in section. FIG. 12 is a side elevation view of a fastening latch. Best Mode for Carrying out the Invention Referring now to FIG. 1, a cowling 20, comprised of a cowling body 22, a forward bearing 24, and an aft bearing 25 (see FIG. 4), is disposed on an aircraft 26 over a cavity 27 containing various engine components 28. A forward bearing guide 29, which engages and constrains the motion of the forward bearing 24, and two aft bearing guides 30, which engage and constrain the motion of the aft bearing 25, are rigidly disposed on the aircraft 26. Referring to FIG. 2, the cowling body 22 is shaped to conform to the aircraft 26 when in a closed position and provides both protection and access to internal engine components 28 of the aircraft 26. Forward portions 31 of the guides 29,30 are shaped to provide an initial vertical displacement of the cowling body 22 during removal in order to supply adequate clearance between the cowling body 22 and the aircraft 26. After the initial vertical motion, the guides 29,30 constrain the cowling body 22 to motion parallel with the aircraft 26. The two aft guides 30 are rigidly fixed under secondary air intake slots 32, as shown in FIG. 3. The intake slots 32, which conform to the taper of the aircraft 26, provide access for the aft bearing 25 to the aft guides 30. Therefore the aft guides 30 are also shaped to conform to the taper of the aircraft 26 and are mirror images about the longitudinal centerline 33 of the aircraft 26. Referring to FIG. 4, the forward bearing 24 is rigidly disposed on the cowling body 22 within existing cowling 20 superstructure 34 and is comprised of a split spherical roller 36, a roller support 38, and a threaded extension 40. The threaded extension 40 and a plurality of projections 42 disposed on the cowling body 22 are utilized as part of a fastening system for the cowling 20. The aft bearing 25 is disposed on the aft portion of the cowling body 22 and, as shown in FIG. 5, is comprised of a pair of split spherical rollers 44, a pair of roller supports 46, a channel 48, and a shaft 50. The channel 48 provides a means to mount the roller supports 46 to the cowling body 22 in a manner restricting the roller supports 46 to lateral motion relative to the cowling body 22, such as by utilizing a plurality of cylindrical bearings 52 which are in rolling contact with tracks 54 on the channel 48 as shown in FIG. 5. The shaft 50, which is supported by the channel 48 in a manner allowing the shaft 50 to rotate freely about the longitudinal axis of the shaft 50, has right-handed threads 56 on one end and left-handed threads 58 on the other end which engage properly threaded apertures 60 in the roller supports 46 to provide coupling of the roller supports 46. The threads 56,58, however, limit the roller supports 46 to convergent and divergent motion along the shaft 50 and resist motion in a common direction along the shaft 50. The convergent/divergent motion permits the aft guides 30 to be shaped to conform to the shape of the aircraft 26. Additionally, the resistance in motion of the aft roller supports 46 provides lateral support to the cowling body 22 during opening and closing of the cowling 20 since lateral loads will attempt to drive the roller supports 46 in a common direction. The split spherical rollers 36,44 move within guides 29,30 which are cylindrical with a longitudinal slot 62 along the underside of the guides 29,30 to accommodate passage therethrough of the roller supports 38,46, as shown in Figs. 6, 7, and 8 for an aft roller 44. The shape of the rollers 44 and guides 29,30, which is identical for both the forward roller 36 and the aft rollers 44, will permit sliding of the rollers 44 within the guides 29,30 in the event of roller 44 seizure. The slot 62, due to its location on the underside of the guides 29,30, will deter the accumulation of ice and debris in the guides 29,30 and thereby deter jamming of the rollers 44 within the guides 29,30. The forward portions 63 of the guides 29,30 are expanded radially in order to disengage the rollers 36,44 from the guides 29,30 when the cowling 20 is fully closed, as shown in FIG. 7. The disengagement prevents damage to the bearings 24,25 and guides 29,30 during operation of the aircraft 26, which is when loading on the cowling 20 is highest. Referring to Figs. 9 and 10, the interaction between shaped edges 68,70 on the cowling body 22 and shaped edges 69,71 of the aircraft 26 provide reactive support when the cowling 20 is in the closed position. The cowling side edge 68 and aircraft side edge 69 are complementary, as shown in FIG. 9, to provide lateral support and the cowling aft edge 70 and aircraft aft edge 71 are complementary, as indicated in FIG. 10, to provide support for vertical loads. This interaction provides for distribution of the loads rather than the concentration of loading which occurred with the prior art technique of external hinge and latch assemblies. Additionally, the discontinuity at the seam 72 between the cowling body 22 and the aircraft 26 is minimal due to the complementary mating. Sealing of the cavity 27 is provided by a gasket 73 located around the periphery of the cowling edge 68,70. During opening operations the cowling body 22 initially slides along the aircraft side edges 69 until the rollers 36,44 engage the guides 29,30. After engagement of the rollers 36,44 and guides 29,30, clearance between the cowling side edges 68 and aircraft side edges 69 is provided by the vertical displacement of the cowling body 22 due to the shape of the forward portion 31 of the guides 29,30 (see FIG. 2). A two-part fastening system is provided to secure the cowling body 22 to the aircraft 26 when closed. The first part is a screw fastener assembly 74 shown in FIG. 11 which consists of a threaded extension 40 pivotally mounted on the forward roller support 38 by use of a spring 76 and positioned to engage with a threaded socket 78 mounted on the aircraft 26. The threaded extension 40 and an aperture 80 in the roller support 38 are mutually keyed such that their interaction prevents rotation of the threaded extension 40. Engagement of the extension 40 and socket 78 occurs when the cowling body 22 is in the closed position and the securing is achieved by operation of a remotely located rotational mechanism (not shown) for rotating the socket 78. The spring 76 mounting arrangement provides an alignment mechanism, pressure to ensure thread engagement, and protection against damage due to exposure of the threaded extension 40. An alternative embodiment (not shown) of the screw fastener assembly 74 has the threaded extension disposed on the aircraft 26 in a manner permitting rotation and the socket 78 disposed on the cowling body 22. The screw fastener assembly is also utilized during the opening and closing operations of the cowling. The screw fastener assembly provides a mechanical advantage to the operator which makes the cowling, which initially slides along the aircraft side edges until the rollers engage the guides, easier to open. The same mechanical advantage also allows the operator to tightly seal the cavity during closing operations. The second part of the fastening system is a redundant measure provided as a safety feature in case of failure of the screw fastener assembly 74 and is illustrated in FIG. 12. A plurality of spring biased latches 82 are pivotally mounted to the aircraft 26 and positioned to engage with the projections 42 rigidly mounted on the cowling body 22 (see FIG. 4). The latches 82 are resiliently biased by respective springs 84. Engagement of the latches 82 and projections 42 occurs automatically upon closing of the cowling 20 and disengagement is achieved by operation of a remotely located release mechanism (not shown). For convenience of operation the release mechanism may be combined with the screw fastener rotary mechanism, such as by utilization of a push-pull, rotary device (not shown). The embodiment of the invention as illustrated in FIGS. 1 to 5 shows a three point attachment mechanism for an aircraft cowling 20. It should be obvious to those skilled in the art that a modified number of attachment points may be used, such as by increasing the number of bearings or by increasing the number of attachment points associated with each bearing, without departing from the spirit and scope of the invention.

Claims: Aircraft cowling attachment mechanism for attaching a cowling body (22) to an aircraft (26), the cowling body (22) being movable between an open and closed position and being shaped to conform to the aircraft (26) in the closed position, wherein the attachment mechanism comprises: forward and aft guides (29, 30) rigidly disposed on the aircraft (26); forward and aft bearings (24, 25) disposed in combination with the cowling body (22) and engaged with said forward and aft guides (29, 30), respectively, in a manner permitting translation of said forward and aft bearings (24, 25) along said respective forward and aft guides (29,30) to move the cowling body (22) generally parallel with the aircraft (26) between the open and closed positions; characterized by two said aft guides (30) having a convergent/divergent shape and being mirror images of each other with respect to the longitudinal centerline (33) of the aircraft (26); said aft bearing (25) including a channel (48) for disposing said aft bearing (25) in combination with the cowling body (22), a pair of roller supports (46) engaged with said channel (48) in a manner permitting convergent/divergent lateral motion of said roller supports (46) with respect to the cowling body (22) during movement thereof between the open and closed positions, and a pair of split spherical rollers (44) rotatably mounted in combination with said roller supports (46) and engaged with said aft guides (30) in a manner permitting translation of said split spherical rollers (44) along said aft guides (30) to move the cowling body (22) between the open and closed positions, said bearing (25) further comprising a shaft (50) having right-handed threads (56) on one end thereof and left-handed threads (58) on the other end thereof, and wherein each of said roller supports (46) has a threaded aperture (60) for rotatably coupling said threaded ends (56, 58) of said shaft (50) with said pair of roller supports (46) wherein rotation of said threaded ends (56, 58) of said shaft (50) in said threaded apertures (60) restricts said pair of roller supports (46) to convergent/divergent lateral motion with respect to the cowling body (22) during movement thereof between the open and closed positions. Cowling attachment mechanism of claim 1, characterized in that said channel (48) of said aft bearing (25) includes tracks (54) and that said pair of roller supports (46) includes a plurality of cylindrical bearings (52) engaged with said tracks (54) in a manner permitting the convergent/divergent lateral motion of the pair of roller supports (46) with respect to the cowling body (22) during movement thereof between the open and closed positions. Cowling attachment mechanism of claim 1, characterized in that said forward bearing (24) includes a roller support (38) disposed in combination with the cowling body (22), a split spherical roller (36) rotatably mounted in combination with said roller support (38) and engaged with said forward guide (29) in a manner permitting translation of said forward bearing (24) along said forward guide (29) to move the cowling body (22) between the open and closed positions, and a threaded extension (40) pivotally mounted on said roller support (38), and wherein said cowling attachment mechanism is further characterized by a screw fastener assembly (74) that includes a threaded socket (78) mounted on the aircraft (26), said threaded extension (40) positioned to engage said threaded socket (78) with the cowling body (22) in the closed position, and means for effecting relative rotation between said threaded extension (40) and said threaded socket (78) to secure the cowling body (22) to the aircraft (26). Cowling attachment mechanism of claim 1, characterized in that said forward and aft guides (29, 30) have forward portions (31) shaped to provide an initial vertical displacement of the cowling body (22) during movement thereof from the closed position to the open position. Cowling attachment mechanism of claim 1, characterized in that said two aft guides (30) are cylindrical and include a longitudinal slot (62) that accommodates the roller supports (46) such that said pair of split spherical rollers (44) are enclosed within said aft guides (30) in a manner permitting rolling contact therebetween. Cowling attachment mechanism of claim 3, characterized in that said forward guide (29) is cylindrical and includes a longitudinal slot (62) that accommodates the roller support (38) such that said split spherical roller (36) is enclosed within said forward guide (29) in a manner permitting rolling contact therebetween. Cowling attachment mechanism of claim 1, characterized in that the aircraft (26) includes side and aft edges (69, 71) that define a cavity (27) that is covered by the cowling body (22) in the closed position, and that the cowling body (22) includes side and aft edges (68, 70) that are complementary to the side and aft edges (69, 71) of the aircraft (26) and interact therewith to provide reactive support for the cowling body (22) in the closed position, and further characterized by means (73) for sealing the cavity (27) with the cowling body (22) in the closed position.

Inventors: AMELIO ARMAND F, AMELIO, ARMAND F.
Applicants: UNITED TECHNOLOGIES CORP, UNITED TECHNOLOGIES CORPORATION
Application year: 1991
Main classification: B64D29
IPC codes: B64C1, B64D29