Patent Document

STATEMENT OF GOVERNMENT INTEREST 
       [0001]    The U.S. Government has a paid-up license in this invention and the right in limited circumstances to require the patent owner to license others on reasonable terms as provided for by the terms of N00019-02-C-3003 awarded by the United States Navy. 
     
    
     BACKGROUND 
       [0002]    Fairings are often present in the inlet case of aircraft turbofan engines. A fairing is generally bonded to and surrounds and protects an inner strut or other similar structural element within the inlet case. Each inner strut generally extends from a central inner ring to an outer diameter ring of the inlet. Each fairing typically surrounds the full radial length of the inner strut. Composite fairings typically consist of several layers of fiberglass or other materials, bonded together to form the fairing structure. Each fairing has a closed and generally rounded upstream end. From the upstream end, two fairing sides extend downstream and around the inner strut. The sides of the fairing are bonded to sides of the inner strut and continue downstream to form two downstream ends. Fairings and inner struts are generally located upstream of the compressor, combustion, and turbine sections of the turbofan. In some turbofans, the fairings contain sensors and heating elements to prevent the formation of ice within the inlet case and to de-ice areas of the inlet case. 
         [0003]    During operation of the turbofan and during flight, a fairing or its heating elements may become damaged or inoperable. Damage to the fairing or the heating elements may occur due to events such as a bird strike. Inoperability may result because of wear or malfunction. When significant damage to a fairing or its heating elements occurs or the heating elements no longer function properly, the fairing is normally removed and replaced. 
         [0004]    Removing a fairing from the inner strut to which it is bonded can be an arduous task for an aircraft mechanic or operator. In order to remove a fairing from an inner strut, the bond between the two components must be released. Typically, a silicone compound is used to bond the fairing and inner strut. The bondline between the fairing and inner strut typically extends the full length of the inner strut (along the turbofan&#39;s longitudinal axis) and roughly two-thirds the length of the fairing (along the same axis). This bondline generally extends the full radial length of the fairing and inner strut. Due to the relatively large surface area of the bond and the strength of the bond needed to ensure adequate binding during flight, releasing the bond can be quite difficult. 
         [0005]    Until now, removing a fairing has been difficult. A large number of inner struts extend from the nosecone to the outer diameter ring, usually more than a dozen. This configuration of multiple inner struts and fairings, as well as components farther downstream, makes for small spaces within the inlet case and prevents the use of large tools. Typically, a screwdriver type prybar or a similar small tool was used to pry the fairing away from the inner strut. A utility knife or other small blade was then used to cut away at the bondline. This method of releasing the bond had several faults. First, screwdriver type prybars generally have a limited thickness and an operator would need to pry many times along the radial length of the fairing in order to release the fairing-strut bond. On occasion, an operator would need to pry multiple times in a small area to fully release even a portion of the bond. A typical operator might spend fifteen or more minutes using this method to remove a single fairing. Additionally, due to the time necessary to remove the fairing and the awkward angle at which the operator needed to use a prybar to pry apart the bond, fairing removal was performed only while the operator was on the ground. Second, an operator would have to reach a good distance beyond the downstream ends of the fairing in order to position the screwdriver type prybar to adequately pry. In some instances, this would require the additional removal of downstream components, such as the first set of compressor vanes, before a fairing could be removed. The downstream components would then need to be replaced once the fairing was removed. This increased the time needed to remove and replace a fairing. Third, damage to the inner strut would sometimes result from the use of a prybar to pry the fairing from the strut. When damage to the inner strut occurred, the inner strut would then need to be repaired or replaced. 
         [0006]    Prior fairing removal methods and tools did not meet the needs of aircraft mechanics and operators. Thus, there is still a need for a faster and more efficient method of removing a fairing from an inlet case and still a need for a useful tool to facilitate such a method. 
       SUMMARY 
       [0007]    The present invention provides a fairing removal tool and a method suitable for removing a fairing from an engine inlet case. In one disclosed embodiment, the fairing removal tool includes a handle, a shaft, and a head. The head includes a prying radius, a hook near an end of the head distal to the handle, and a notch located between the hook and the prying radius configured to engage a downstream end of a fairing. The method of removing a fairing entails engaging the hooked end of the fairing removal tool to an overhanging downstream end of a fairing and applying a force on the shaft or handle of the tool to pry the fairing away from the inner strut to which it is bonded. This process is repeated along the length of both downstream ends of the fairing until the bonds between the fairing and the inner strut are completely released and the fairing can be removed from the engine inlet case. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a side view of one embodiment of the fairing removal tool. 
           [0009]      FIG. 2  is a top view of the fairing removal tool of  FIG. 1 . 
           [0010]      FIG. 3  is a cross section view of a fairing with a fairing removal tool engaged to a downstream end of the fairing. 
           [0011]      FIG. 4  is a cross section view of a fairing with a fairing removal tool engaged to a downstream end of the fairing after force has been applied to the fairing removal tool. 
           [0012]      FIG. 5  is a view of the fairing removal tool engaging a fairing in an engine inlet. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    Referring to the figures, an illustrative embodiment of a fairing removal tool according to the present invention is generally indicated by reference numeral  10 .  FIGS. 1 and 2  illustrate a side view and a top view of one embodiment of a fairing removal tool  10 , respectively. The fairing removal tool  10  includes a handle  12 , a shaft  14 , and a head  16 . The handle  12  allows an operator to easily grip the fairing removal tool. The handle  12  may be contoured to fit comfortably in an operator&#39;s hand. The handle  12  may also be shaped, textured, or covered with a non-slip material so that an operator may easily grip the handle securely with a minimum of slippage when the fairing removal tool is in use. The shaft  14  connects the handle  12  to the head  16 . 
         [0014]    The head  16  includes a prying radius  18 . While the fairing removal tool  10  of  FIGS. 1 and 2  has a generally curved convex prying radius  18 , the fairing removal tool of the present invention is not limited to this configuration. The prying radius  18  may also have a flattened V-shape or other geometries suitable for providing a fulcrum or fulcrums necessary for effective prying. 
         [0015]    The prying radius  18  may include an effective prying area  24  and a prying relief  26 . The effective prying area  24  is the area of the head  16  that contacts the fairing as it is removed. Contact points along the effective prying area  24  act as fulcrums as the fairing is pried from an inner strut. A more detailed discussion of fairing removal is provided below. In an exemplary embodiment, the effective prying area  24  will have a length approximately equal to the length of the bond between the fairing and the attached inner strut. In such an embodiment, the entire or nearly the entire effective prying area  24  can be utilized as a fulcrum during release of the bond joining the fairing and inner strut. The prying relief  26  is the area of the fairing removal tool head that does not directly contact the fairing during fairing removal. 
         [0016]    The head  16  also includes a hook  20  near the end of the head  16  distal the handle  12  and a notch  22  located between the hook  20  and the prying radius  18 . The hook  20  and notch  22  are configured to engage a downstream end of a fairing allowing an operator to pry and disengage the bond between the fairing and a joined inner strut, or a similar structure, bonded to the fairing. The hook  20  and notch  22  allow an operator to easily position the tool on a downstream end of a fairing.  FIG. 3  illustrates a fairing removal tool  10  engaged to a downstream end of a fairing  28  that is bonded to an inner strut  30 . The downstream end of the fairing is positioned within the notch  22  of the fairing removal tool during use. 
         [0017]    As  FIG. 3  illustrates, when the downstream end of the fairing  28  is engaged with the fairing removal tool  10 , the inner side of the fairing abuts the hook  20  and the end and outer sides of the fairing are located within the notch  22 . Ideally, the hook  20  and notch  22  are configured so that when the fairing removal tool  10  is engaged to a downstream end of a first fairing  28 , an adjacent fairing  32  does not interfere with the shaft  14  and the handle  12  of the fairing removal tool as shown in  FIG. 3 . Thus, an operator may both position the fairing removal tool on the downstream end of the fairing and operate the tool without interference from adjacent fairings. This is accomplished most easily near the outer diameter ring where adjacent struts  30  and fairings  28 ,  32  are spaced apart farthest. Closer to the central inner ring, however, the struts and fairings are closer together. In an exemplary embodiment, the hook  20  and notch  22  are configured so that even near the central inner ring, an adjacent fairing  32  does not interfere with the shaft  14  and the handle  12  of the fairing removal tool when engaged to a fairing. Additionally, the hook  20  and notch  22  do not interfere with the first variable vanes  36 . 
         [0018]    The fairing removal tool acts as a first class lever. Release of a bond  34  between a fairing  28  and an inner strut  30  is accomplished by first engaging a downstream end of the fairing  28  with the hook  20  and notch  22  of the fairing removal tool  10  as illustrated in  FIG. 3  and described above. Once engaged, the operator applies force to the handle  12  or shaft  14  of the fairing removal tool  10  generally in a direction toward the longitudinal axis of the fairing  28  as shown in  FIG. 4  to pry the fairing away from the inner strut. As force is applied to the handle  12  or shaft  14 , the downstream end of the fairing  28  is pulled by the hook  20  away from the inner strut  30 . During prying, the downstream end of the fairing is pulled along the prying radius  18 . As the fairing is pulled, the bond  34  between the fairing  28  and inner strut  30  is released. In an exemplary embodiment, the length of the bond  34  is about equal to the length of the effective prying area  24  of the prying radius  18 . The length of the bond  34  between the fairing  28  and inner strut  30  is typically between about 2 inches (5.1 cm) and about four inches (10.2 cm). 
         [0019]      FIG. 5  illustrates a view from an area of the engine inlet case downstream of the fairings where engagement of the fairing tool with a downstream end of a fairing has occurred and prying of the fairing has begun. The area of the fairing  28  engaged with fairing removal tool  10  has become separated from the inner strut  30 . Areas of the fairing not directly engaged to the fairing removal tool but adjacent such areas have also separated from the inner strut, but to a lesser degree. Due to the typical strength of the bond  34  between a fairing  28  and an inner strut  30  and the lengths of the fairing and inner strut, one instance of prying may be insufficient to release the bond  34  over the entire length of the inner strut. In these instances, it is necessary to repry the fairing at a different location along the length of the fairing. Once the fairing has been pried at enough locations along its length, the bond  34  may be fully released. 
         [0020]    A fairing  28  is typically bonded to an inner strut  30  along both downstream sides ( FIGS. 3 and 4 ). Thus, bonds  34  along both sides of the inner strut  30  must be released before the fairing  28  can be completely removed. The process described above is performed on both sides of the fairing  28  until both bonds  34  are released. Once both bonds  34  are released, the operator may fully remove the fairing  28  from the inner strut  30  and the engine inlet case. 
         [0021]    Dimensions of one exemplary embodiment of the fairing removal tool  10  are provided below. The description of this embodiment does not impose limitations on other possible configurations and dimensions of the fairing removal tool or its components, however. The overall length of one embodiment of the fairing removal tool is about eighteen inches (45.7 cm). The lengths of the handle, shaft, and head are about four inches (10.16 cm), ten inches (25.4 cm), and four inches (10.16 cm), respectively. The width of the head is about one inch (2.54 cm). The depth of the notch  22  is about 0.1 inches (0.254 cm) and the width of the notch  22  (the distance from the hook to the prying radius) is about 0.07 inches (0.178 cm). The angle of the notch  22  relative to the longitudinal axis of the fairing removal tool  10  is about thirty degrees. The width of the head may affect the number of pries necessary to release the bondline between a fairing and an inner strut. Thus, head widths between about 0.5 inches (1.27 cm) and about two inches (5.08 cm) may be suitable for smaller or larger engine inlet cases. The fairing removal tool and its components may be comprised of steel or any other materials strong enough to facilitate the fairing removal process. 
         [0022]    The configurations of the fairing, inner strut, and the fairing removal tool allow an operator to work from the front of the engine inlet without the need for the operator to position his hand downstream of the fairing. The design of the fairing removal tool also allows fairing removal without the need for removing engine inlet components downstream of the fairing and inner strut, such as the first row of variable vanes. The design of the fairing removal tool further allows an operator to engage in fairing removal from the ground or while on the wing of the aircraft near the engine inlet. 
         [0023]    Although the present invention has been described with reference to exemplary embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.

Technology Category: y