Abstract:
Apparatuses and methods for preventing foreign object damage (FOD) to aircraft engines are disclosed. In one embodiment, a deployable blocker is coupled to a wing portion and/or a fuselage portion of the aircraft and is configured to prevent debris from travelling on a direct trajectory from a landing gear wheel to an engine air inlet. In other embodiments, the blocker can prevent debris from bouncing off the wing lower surface into the engine inlet, or sticking to the wing lower surface and falling into the engine inlet. The deployable blocker can cover at least a portion of the landing gear when the landing gear is retracted and the blocker assembly stowed. In another embodiment, the blocker can be mounted to the landing gear.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    The present application claims priority to U.S. Provisional Application No. 60/420,748, filed Oct. 22, 2002 and incorporated herein in its entirety by reference. 
     
    
     
       TECHNICAL FIELD  
         [0002]    The following disclosure relates generally to apparatuses and methods for preventing foreign object damage (FOD) to aircraft engines and, more particularly, to main landing gear door assemblies and other blocking structures for preventing FOD to aircraft engines.  
         BACKGROUND  
         [0003]    Foreign object damage (FOD) to an aircraft engine can cause an unexpected engine shut-down or an unscheduled engine replacement. Such FOD can be caused by various types of debris, including runway debris (e.g., water, gravel, nuts and bolts, etc.) and aircraft debris (e.g., tire pieces, accumulated ice, landing gear parts, etc.). These types of debris can be thrown or otherwise propelled into the engine inlet by a landing gear wheel during take-off or landing, especially if the wheel is positioned forward of the engine air inlet. Existing structures for preventing foreign materials from being ingested into the engine inlet may be heavy and/or may not block all such materials. For example, some existing devices may block water but not solid objects, and others may block only certain material trajectories.  
         SUMMARY  
         [0004]    The present invention is directed generally toward aircraft devices for intercepting foreign objects to prevent foreign object damage. An aircraft in accordance with one aspect of the invention includes a fuselage portion, a wing portion coupled to the fuselage portion, and an engine nacelle having an air inlet and depending from at least one of the fuselage portion and the wing portion. A landing gear can also depend from at least one of the wing portion and the fuselage portion. A deployable blocker can be coupled to at least one of the wing portion and the fuselage portion and can be movable between a stowed position and a deployed position, with at least a portion of the blocker being located between the landing gear and the air inlet when in the deployed position to prevent at least a solid object propelled by the landing gear from entering the air inlet.  
           [0005]    In a further aspect of the invention, the landing gear is movable between an extended position and a retracted position, and the blocker can cover at least a portion of the landing gear when the landing gear is in the retracted position and the blocker is in the stowed position. The landing gear can include at least one tire and the blocker can intersect a straight line extending between the at least one tire and the air inlet. In another embodiment, the blocker can prevent at least a solid object propelled by the landing gear from striking a lower surface of the wing portion and then entering the inlet. In still another embodiment, the blocker can include a blocker device positioned between an upper surface of a landing gear tire and at least one of the wing portion, the fuselage portion, and the engine nacelle to intercept at least a solid object propelled by the landing gear. The blocker device can be supported by the landing gear from a position below the blocker device.  
           [0006]    A method in accordance with another aspect of the invention includes extending the landing gear of an aircraft, engaging the landing gear with the ground, and moving the aircraft along the ground on the landing gear. The method can further include preventing at least a solid object propelled by the landing gear from entering an engine inlet of the aircraft by moving a deployable blocker coupled to at least one of the wing portion and the fuselage portion of the aircraft from a stowed position to a deployed position to place at least a portion of the blocker between the landing gear and the inlet. In a further aspect of this embodiment, the method can include preventing a tire fragment from entering the inlet. In other particular embodiments, the method can include preventing at least a solid object from striking at least one of the wing portion and the fuselage portion and then bouncing into the inlet, and/or sticking to at least one of the wing portion and the fuselage portion and falling into the inlet. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is a front elevation view of a portion of an aircraft having a blocker assembly configured in accordance with an embodiment of the invention.  
         [0008]    [0008]FIG. 2 is a side elevation view of a portion of the aircraft of FIG. 1 illustrating aspects of the blocker assembly configured in accordance with an embodiment of the invention.  
         [0009]    [0009]FIG. 3A is a front elevation view, and FIG. 3B is a side elevation view, of a portion of an aircraft having a blocker assembly configured in accordance with another embodiment of the invention.  
         [0010]    [0010]FIG. 4 is a bottom plan view of a portion of the aircraft shown in FIG. 3A, configured in accordance with an embodiment of the invention and illustrating possible ranges of debris trajectories.  
         [0011]    [0011]FIG. 5A is a front elevation view, and FIG. 5B is a side isometric view, of a portion of an aircraft having a blocker assembly coupled to a landing gear and configured in accordance with an embodiment of the invention.  
         [0012]    [0012]FIG. 6 is an enlarged rear elevation view of a lower portion of a landing gear illustrating aspects of the blocker assembly of FIGS.  5 A- 5 B configured in accordance with an embodiment of the invention.  
         [0013]    [0013]FIG. 7 is an enlarged isometric view of the lower portion of the landing gear of FIG. 6 illustrating aspects of the blocker assembly configured in accordance with an embodiment of the invention.  
         [0014]    [0014]FIG. 8 is a top view of a wheel truck illustrating further aspects of the blocker assembly of FIGS.  5 A- 7  configured in accordance with yet another embodiment of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0015]    The following disclosure describes blocker devices, including landing gear door assemblies and related structures for preventing FOD to aircraft engines. Certain specific details are set forth in the following description and the Figures to provide a thorough understanding of various embodiments of the invention. Certain well-known details often associated with aircraft and aircraft landing gears are not set forth in the following disclosure, however, to avoid unnecessarily obscuring the various embodiments of the invention. Further, those of ordinary skill in the relevant art will understand that they can practice other embodiments of the invention without several of the details described below.  
         [0016]    [0016]FIG. 1 is a front elevation view of a portion of an aircraft  100  having a blocker assembly  102  configured in accordance with an embodiment of the invention and positioned to intercept at least solid foreign objects and prevent them from striking other parts of the aircraft  100 . Accordingly, the blocker assembly  102  can also intercept non-solid objects (e.g., water droplets or spray) and prevent them from striking other parts of the aircraft  100 . In one aspect of this embodiment, the aircraft  100  is an aft wing aircraft having a wing or wing portion  120  extending outwardly from an aft portion of a fuselage or fuselage portion  110 . The aircraft  100  can further include a smaller wing or canard (not shown) extending outwardly from the fuselage  110  forward of the wing  120 . In other embodiments, the aircraft  100  can have other wing configurations. For example, in another embodiment, the aircraft  100  can have a mid-wing configuration or a blended wing-body configuration.  
         [0017]    In another aspect of this embodiment, the aircraft  100  has landing gear  101 , which includes a nose gear  103  and main landing gear  104  aft of the nose gear  103 . An engine nacelle  112  is positioned above the landing gear  101  and can house a turbofan engine. Certain aspects of the invention, discussed below in the context of the main landing gear  104 , are also applicable to other portions of the landing gear  101 , for example, the nose gear  103 . The main landing gear  104  can be pivotally attached to the wing  120  at a trunnion  108  and can include a wheel truck  106 . The main landing gear  104  can be pivotable about the trunnion  108  to move the wheel truck  106  between a static deployed position for supporting the aircraft  100  on the ground (as shown in FIG. 1), and a static retracted position (not shown) in which the main landing gear  104  is stowed for flight in a wheel well  130  within the wing  120 . For example, in the illustrated embodiment the main landing gear  104  is forwardly retractable into the wheel well  130  about the trunnion  108  between the static deployed position and the static retracted position. In other embodiments, the main landing gear  104  can retract in other directions. For example, in another embodiment, the main landing gear  104  can retract rearwardly into the wheel well  130 . In a further embodiment, the main landing gear  104  can retract inwardly, at least partially into the fuselage  110 .  
         [0018]    In a further aspect of this embodiment, the engine nacelle  112  is fixedly attached at least proximate to a lower wing surface  122  and includes an engine air inlet  114 . In the illustrated embodiment, the engine air inlet  114  is positioned at least generally aft of the wheel truck  106  when the wheel truck  106  is in the static deployed position. In another aspect of this embodiment, the blocker assembly  102  includes a solid and generally rigid panel  105  that is hingedly attached to the wing  120  and is movable between an open or deployed position (as shown in FIG. 1), and a closed or retracted position. In the closed position, the blocker assembly  102  can close off the wheel well  130  and can accordingly function as both a landing gear door and blocker for foreign objects. In the deployed position, the blocker assembly  102  extends downwardly to block at least some (and in at least one embodiment, all) direct lines-of-sight between the wheel truck  106  and the engine air inlet  114 . Such lines-of-sight can be defined by the region extending between lines  130   a  and  130   b . Accordingly, the blocker assembly  102  of the illustrated embodiment prevents debris generated, kicked-up or otherwise propelled by the wheel truck  106  from travelling on a direct trajectory to the engine air inlet  114  and being ingested by the engine nacelle  112 .  
         [0019]    [0019]FIG. 2 is a side elevation view of a portion of the aircraft  100  of FIG. 1 illustrating the blocker assembly  102  configured in accordance with an embodiment of the invention. In one aspect of this embodiment, the blocker assembly  102  includes a gear door portion  201  and a FOD portion  203 . The FOD portion  203  can extend close enough to the ground and far enough aft in the deployed position to block line-of-sight trajectories from the wheel truck  106  to the engine air inlet  114 . The gear door portion  201  can be configured to close off at least a portion of the wheel well  130  when the main landing gear  104  is retracted.  
         [0020]    In a further aspect of this embodiment, the gear door portion  201  and the FOD door portion  203  can be longitudinally aligned with each other and at least partially integrated as a single hinged panel that can be hydraulically or mechanically deployed as the wheel truck  106  moves into the static deployed position, and mechanically locked in a closed or retracted position when the wheel truck  106  moves into the static retracted position. When the blocker assembly  102  is in the retracted position, the gear door portion  201  can at least partially cover the wheel well  130 , while at least part of the FOD portion  203  can be positioned at least approximately flush against the lower wing surface  122  adjacent to the wheel well  130 . One advantage of this configuration is that both functions (i.e., wheel well coverage and FOD prevention) can be accomplished without having to construct and integrate two separate mechanical systems into the wing  120 . In other embodiments, each of the gear door portion  201  and the FOD portion  203  can cover more or less of the wheel well  130 . For example, if the wheel well  130  is extended further aft in the wing  120  than is shown in FIG. 2, then the entire FOD portion  203  can be configured to cover at least a portion of the wheel well  130 . In yet other embodiments, the gear door portion  201  and the FOD portion  203  can be separate from each other and independently movable relative to each other.  
         [0021]    In a further aspect of this embodiment, the profiles of the gear door portion  201  and the FOD portion  203  are configured to minimize surface area while still providing adequate FOD protection. The profile of the gear door portion  201  can include a swept or highly-swept leading edge  204  to reduce or eliminate vortex shedding from the blocker assembly  102  into the engine air inlet  114 . In other embodiments, the gear door portion  201  and the FOD portion  203  can have other profiles without departing from the spirit or scope of the present invention. For example, in another embodiment, the profile of the gear door portion  201  can be at least approximately rectangular without the swept leading edge  204 .  
         [0022]    [0022]FIG. 3A is a front elevation view, and FIG. 3B is a side elevation view, of a portion of an aircraft  300  having a blocker assembly  302  configured in accordance with another embodiment of the invention. Referring to FIGS. 3A and 3B together, in one aspect of this embodiment, the aircraft  300  has a mid-wing configuration with a wing  320  extending outwardly from a mid portion of a fuselage  310 . The aircraft  300  can have a landing gear  301  that includes a main landing gear  304 . An engine nacelle  312  is positioned above the landing gear  301 . The main landing gear  304  can include a wheel truck  306  and can be at least approximately similar in structure and function to the main landing gear  104  described above with reference to FIG. 1. The engine nacelle  312  can be fixedly attached to a wing lower surface  322  and can include an engine air inlet  314 . In contrast to the engine air inlet  114  of FIG. 1, the engine air inlet  314  is positioned forward of the wheel truck  306  when the wheel truck  306  is in a static deployed position as shown in FIG. 3A. Accordingly, debris cannot travel on a direct line-of-sight trajectory from the wheel truck  306  to the engine air inlet  314 . As a result, the blocker assembly  302  does not need to extend as far downwardly as the blocker assembly  102  of FIG. 1 to prevent such debris from entering the engine nacelle  312 .  
         [0023]    [0023]FIG. 4 is a bottom plan view of the portion of the aircraft  300  shown in FIGS. 3A and 3B, illustrating ranges of debris trajectories. In one aspect of this embodiment, the wing  320  includes a leading edge  324  positioned forward of the engine air inlet  314 . Debris generated or kicked up by the wheel truck  306  can be directed forwardly and upwardly from the wheel truck  306  and can strike the lower wing surface  322  in a first zone  326  (e.g., a bounce zone) or a second zone  328  (e.g., a stick zone). The first (bounce) zone  326  extends laterally inboard from the engine air inlet  314 . Debris from the wheel truck  306  striking the first (bounce) zone  326  can bounce or reflect back relative to the aircraft  300  at an angle into the engine air inlet  314 , as indicated by bounding trajectories  340  (shown in phantom lines). The second (stick) zone  328  is laterally aligned with the engine air inlet  314 , as indicated by dashed lines  341 . Debris from the wheel truck  306  striking the second (stick) zone  328  may temporarily stick to the lower wing surface  322  and subsequently detach and travel directly aft relative to the aircraft  300 , parallel to the line of flight and into the engine air inlet  314 . Accordingly, in the illustrated embodiment, the blocker assembly  302  is expected to prevent all debris from the wheel truck  306  from striking the the second zone  328  and travelling back into the engine air inlet  314 . The blocker assembly  302  may not block all debris from the wheel truck  306  from striking the first zone  326 .  
         [0024]    In another embodiment, the blocker assembly  302  can include an extension  460  (shown in dashed lines in FIG. 4) extending forward toward the wing leading edge  324 . The extension  460  can, in one aspect of this embodiment, be fixed relative to the lower wing surface  322 . In other embodiments, the extension  460  can be at least partially integrated with the rest of the blocker assembly  302  to hingedly open and close relative to the lower wing surface  322 . In any of these embodiments, the extension  460  can completely or at least more completely block debris propelled by the wheel truck  306  from striking the first zone  326 .  
         [0025]    [0025]FIG. 5A is a front elevation view, and FIG. 5B is a side isometric view, of a portion of an aircraft  500  having a blocker assembly  550  (for example, a “FOD bonnet”) configured in accordance with an embodiment of the invention. Referring to FIGS. 5A and 5B together, in one aspect of this embodiment, the aircraft  500  includes a main landing gear  504  having a wheel truck  506 . The wheel truck  506  includes a chassis  560  that carries wheels  507  with tires  508 . The main landing gear  504  can be pivotally attached to a wing  520  with a strut  505  and can be inwardly retractable for stowage at least partially within a fuselage  510  during flight. In other embodiments, the main landing gear  504  can retract in other directions for stowage during flight. For example, in other embodiments, the main landing gear  504  can retract either forwardly or rearwardly for stowage in the wing  520 . In another aspect of this embodiment, the aircraft  500  includes an engine nacelle  512  having an engine air inlet  514  positioned forward of the wheel truck  506  in a manner generally similar to that of the engine air inlet  314  described above with reference to FIGS. 3A and 3B. In a further aspect of this embodiment, the blocker assembly  550  can prevent debris directed forward from the wheel truck  506  from striking a lower wing surface  522  and then traveling back relative to the aircraft  500  and into the engine nacelle  512  via the engine air inlet  514 .  
         [0026]    [0026]FIG. 6 is an enlarged rear elevation view of a lower portion of the main landing gear  504  illustrating aspects of the blocker assembly  550  of FIGS.  5 A- 5 B configured in accordance with an embodiment of the invention. In one aspect of this embodiment, the blocker assembly  550  includes a support structure  552  and a deflector panel  554 . The deflector panel  554  is positioned above the upper surfaces of the tires  508 , and can be at least approximately horizontal with respect to the ground, or inclined upwardly or downwardly as it extends over at least a portion of the wheel truck  506 . The deflector panel  554  can extend laterally from the strut  505 , and can extend further on one side of the strut  505  than the other, based on the relative position of the engine air inlet  514  (not shown). The deflector panel  554  can further include a cutout  556  to accommodate the strut  505 .  
         [0027]    In another aspect of this embodiment, the support structure  552  attaches the deflector panel  554  to the chassis  560  of the wheel truck  506 . For example, the support structure  552  can be attached to axles  509  on which the wheels  507  are mounted. In other embodiments, the support structure  552  can be attached to other portions of the landing gear  504  or other structural members without departing from the spirit or scope of the present invention. For example, in another embodiment, the blocker assembly  550  can be mounted to at least a portion of the strut  505  instead of the wheel truck chassis  560 . In any of these embodiments, the support structure  552  can support the deflector panel  554  from below. One feature of this arrangement is that debris from the wheel truck  506  impacting the deflector panel  554  can impart tension loads on the support structure  552 . Tension loads can generally be carried by the structural members of the support structure  552  more efficiently than compression loads. Accordingly, the support structure  552  of the illustrated embodiment can be made lighter than a support structure that carries loads imparted to the deflector panel  554  in compression (e.g., a support structure that carries the deflector panel  554  from above). Another feature of this arrangement is that the deflector panel  554  follows the motion of the tires  508  because the deflector panel  554  is supported by the truck  506 . An advantage of this feature is that the deflector panel  554  can more consistently block trajectories originating at the tires  508 , even as the tires  508  bounce on the runway, or assume a “toes up” or “toes down” attitude just prior to touchdown or after takeoff.  
         [0028]    [0028]FIG. 7 is an enlarged isometric view of a lower portion of the landing gear  504  illustrating further aspects of the blocker assembly  550  shown in FIGS. 5A and 5B.  
         [0029]    [0029]FIG. 8 is a top view of the wheel truck  506  illustrating further aspects of the blocker assembly  550  shown in FIGS. 5A and 5B.  
         [0030]    From the foregoing, it will be appreciated that specific embodiments of the invention have been described herein for purposes of illustration, but that various modifications may be made without deviating from the spirit and scope of the invention. Accordingly, the invention is not limited except as by the appended claims.