Abstract:
An engine mount may include a clevis and a lug defining a hole therethrough. A pin may be joined to the clevis and may extend through the hole of the lug with the pin and the lug defining a clearance therebetween. A trigger system may be disposed on the lug and operatively associated with the pin.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This patent application is a 35 USC §371 US national stage filing of International Patent Application No. PCT/US2014/020264 filed on Mar. 4, 2014, and claims priority under 35 USC §119(e) to U.S. Provisional Patent Application Ser. No. 61/790,946, filed on Mar. 15, 2013. 
     
    
     TECHNICAL FIELD 
       [0002]    The subject matter of the present disclosure relates generally to gas turbine engines and, more particularly, relates to waiting fail safe lugs for engine mounts. 
       BACKGROUND 
       [0003]    Various engine mounting systems are used to mount gas turbine engines to aircraft. Typically, gas turbine engines are mounted to the wing, fuselage, or tail of an aircraft and may be mounted at various positions between its forward and aft ends. The engine mounts carry various loads to the aircraft such as vertical loads from the engine weight, axial loads due to the thrust generated by the engine, lateral loads from wind buffeting, and roll loads caused from rotary operation of the engine. In addition to carrying these loads, the engine mounts must also withstand both the axial and radial thermal expansion and contraction of the engine during operation. 
         [0004]    For example, a front engine mount having a pair of circumferentially spaced apart primary links is one type of mount utilized in conventional engine mounting systems. Each primary link is joined at one end to the aircraft and at the other end to an engine casing, such as the fan case. The front engine mount, as well as aft mounts and other mounts within the engine mounting system, typically incorporates a waiting fail safe system to provide a redundant load path in case the primary load path fails. The waiting fail safe load path does not engage under the normal or limit maneuver load condition. 
         [0005]    In the case of these types of front engine mounts, the waiting fail safe system is positioned in between the two primary links. In the event that either primary link fails, the waiting fail safe system is engaged. While effective, the waiting fail safe system of previous designs does not, when engaged, prevent the engine from upward or downward movement due to subsequent vertical loads. The kinetic energy associated with the upward or downward movement will result in an impact force that is higher than the design load, which is determined by the equilibrium under the assumption of static determination. Typically, to account for this potential impact force, a dynamic amplification factor is applied to the static load, as well as fatigue spectrum, to ensure the waiting fail safe system has adequate capability. However, incorporating the dynamic amplification factor into the design results in a higher design load for the waiting fail safe system, and hence contributes to added weight. 
         [0006]    There is a need for improved waiting fail safe systems. 
       SUMMARY 
       [0007]    In accordance with an aspect of the disclosure, an engine mount for mounting a case of a gas turbine engine to an aircraft pylon is provided. The engine mount may include a clevis and a lug defining a hole therethrough. A pin may be joined to the clevis and may extend through the hole of the lug with the pin and the lug defining a clearance therebetween. A trigger system may be disposed on the lug and operatively associated with the pin. 
         [0008]    In accordance with another aspect of the disclosure, the trigger system may include a trigger, a spring, a slider block and a channel. 
         [0009]    In accordance with yet another aspect of the disclosure, the trigger may include a straight portion and an arcuate portion. The straight portion may include an activating nub and the arcuate portion may include a locking catch. 
         [0010]    In accordance with still another aspect of the disclosure, the activating nub may be operatively engageable with the pin. 
         [0011]    In accordance with still yet another aspect of the disclosure, the slider block may be slidable within the channel and may be engageable with the pin. 
         [0012]    In further accordance with another aspect of the disclosure, the slider block may include a notch which may be operatively engageable with the locking catch. 
         [0013]    In further accordance with still another aspect of the disclosure, the spring may be disposed within the channel. The spring may be operatively connected at one end to the slider block and may be operatively connected at another end to an end wall of the channel. 
         [0014]    In even further accordance with still another aspect of the disclosure, the trigger system may be movable between a disengaged position and an engaged position in contact with the pin. 
         [0015]    In accordance with another aspect of the disclosure, an assembly for a gas turbine engine is provided. The assembly may include a case. At least a first engine mount may be secured to the case. At least a first lug may be joined to the case. The at least first lug may define a hole therethrough. At least a first pin may be joined to the at least first engine mount. The at least first waiting fail safe pin may extend through the hole of the at least first lug with the at least first pin and the at least first lug defining a clearance therebetween. A trigger system may be disposed on the at least first lug and may be operatively associated with the at least first pin. 
         [0016]    In accordance with yet another aspect of the disclosure, the activating nub may be operatively engageable with the at least first pin. 
         [0017]    In accordance with still another aspect of the disclosure, the slider block may be slidable within the channel and may be engageable with the at least first pin. 
         [0018]    In accordance with still yet another aspect of the disclosure, the at least first engine mount may include a mount beam. A first and second mount link may each be joined at one end to the mount beam and joined at another end to respective first and second mount lugs, which may be joined to the case. 
         [0019]    In further accordance with yet another aspect of the disclosure, the at least first waiting fail safe lug may be disposed on the case between the first and second mount lugs. 
         [0020]    In accordance with another aspect of the disclosure, a method of configuring an engine mount for a gas turbine engine is provided. The method entails mechanically coupling a trigger system to a lug of a fan case with the trigger system configured for selective engagement of a pin coupled to the engine mount. 
         [0021]    In accordance with yet another aspect of the disclosure, the method may include the trigger system with a trigger, a spring, a slider block and a channel. 
         [0022]    In accordance with still yet another aspect of the disclosure, the method may include the trigger with an activating nub configured to initiate movement of the trigger system from a disengaged position to an engaged position when the pin contacts the activating nub. 
         [0023]    In further accordance with yet another aspect of the disclosure, the method may include the slider block configured for selective contact with the pin and defines a notch for operative engagement with the trigger. 
         [0024]    In even further accordance with yet another aspect of the disclosure, the method may include the trigger system preventing subsequent movement of the pin when the trigger system is moved to an engaged position. 
         [0025]    Other aspects and features of the disclosed systems and methods will be appreciated from reading the attached detailed description in conjunction with the included drawing figures. Moreover, selected aspects and features of one example embodiment may be combined with various selected aspects and features of other example embodiments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    For further understanding of the disclosed concepts and embodiments, reference may be made to the following detailed description, read in connection with the drawings, wherein like elements are numbered alike, and in which: 
           [0027]      FIG. 1  is a schematic side view of a gas turbine engine with portions of the nacelle thereof sectioned and broken away to show details of the present disclosure; 
           [0028]      FIG. 2  is a side view of a fan case with an engine mount, constructed in accordance with the teachings of this disclosure; 
           [0029]      FIG. 3  is a front view of a fan case with an engine mount, constructed in accordance with this disclosure; 
           [0030]      FIG. 4  is a top view of a fan case with an engine mount, constructed in accordance with this disclosure; 
           [0031]      FIG. 5  is a front view of an engine mount, constructed in accordance with this disclosure; 
           [0032]      FIG. 6  is a front view of an engine mount with portions sectioned and broken away to show details of the present disclosure; 
           [0033]      FIG. 7  is a detailed front view of a waiting fail safe system in a disengaged position, constructed in accordance with this disclosure; 
           [0034]      FIG. 8  is a detailed front view of a waiting fail safe system in an engaged position, constructed in accordance with this disclosure; and 
           [0035]      FIG. 9  is a flowchart illustrating a method of the present disclosure. 
       
    
    
       [0036]    It is to be noted that the appended drawings illustrate only certain illustrative embodiments and are therefore not to be considered limiting with respect to the scope of the disclosure or claims. Rather, the concepts of the present disclosure may apply within other equally effective embodiments. Moreover, the drawings are not necessarily to scale, emphasis generally being placed upon illustrating the principles of certain embodiments. 
       DETAILED DESCRIPTION 
       [0037]    Referring now to  FIG. 1 , a gas turbine engine constructed in accordance with the present disclosure is generally referred to by reference numeral  10 . The gas turbine engine  10  includes a compressor  12 , a combustor  14  and a turbine  16 . The serial combination of the compressor  12 , the combustor  14  and the turbine  16  is commonly referred to as a core engine  18 . The core engine  18  lies along a longitudinal central axis  20 . A core engine case  22  surrounds the core engine  18 . 
         [0038]    Air enters compressor  12  at an inlet  24  and is then pressurized. The pressurized air subsequently enters the combustor  14 . In the combustor  14 , the air mixes with fuel and is burned, generating hot combustion gases that flow downstream to the turbine  16 . The turbine  16  extracts energy from the hot combustion gases to drive the compressor  12  and a fan  26  having airfoils  28 . As the turbine  16  drives the fan  26 , the airfoils  28  rotate so as to take in ambient air. This process accelerates the ambient air flow  30  to provide the majority of the useful thrust produced by the engine  10 . Generally, in modern gas turbine engines, the fan  26  has a much greater diameter than the core engine  18 . Because of this, the ambient air flow  30  through the fan  26  can be 5-10 times higher, or more, than the combustion air flow  32  through the core engine  18 . The ratio of ambient air flow  30  through the fan  26  relative to the combustion air flow  32  through the core engine  18  is known as the bypass ratio. 
         [0039]    An annular fan case  34  surrounds the fan  26 . The engine  10  may be mounted to an aircraft pylon  36  by a forward mount  38  and an aft mount  40 . As seen in  FIGS. 1-6 , the forward mount  38  may be disposed on the fan case  34  at a location that facilities joining to the aircraft pylon  36 . Similarly, the aft mount  40  may be disposed on the core engine case  22  at a location that facilitates joining to the aircraft pylon  36 . As best seen in  FIGS. 5-6 , the forward mount  38  may include a forward mount beam  42 , which may include first and second primary forward mount links  44 ,  46 . The forward mount  38  may also include a substantially centrally located clevis  47 , which extends radially inwardly. The forward mount beam  42  may be secured to the aircraft pylon  36  by a conventional means such as but not limited to bolts and nuts. Each link  44 ,  46  may be joined at one end to the forward mount beam  42  and joined at the other end to complimentary first and second primary forward mount lugs  48 ,  50 , respectively. Each primary forward mount lug  48 ,  50  may be disposed onto the fan case  34  by a conventional means such as, but not limited to, welding. The links  44 ,  46  may be joined to forward mount beam  42  and respective primary forward mount lugs  48 ,  50  by conventional bolts and nuts  52 , so as to create a primary load path for carrying the vertical load of the engine under normal (non-failure) conditions. 
         [0040]    As seen best with more detail in  FIGS. 7-8 , the forward mount  38  of  FIG. 6 , which depicts a portion of clevis  47  removed to show the waiting fail safe lug  56 , may also include a waiting fail safe system  54 . The waiting fail safe system  54  may include a waiting fail safe lug  56  and a waiting fail safe pin  58 . The waiting fail safe pin  58  may be joined to the clevis  47 . The waiting fail safe lug  56  may be disposed on the fan case  34  between the first and second primary forward mount lugs  48 ,  50 . The waiting fail safe lug  56  may include a pin hole  60  for receiving the waiting fail safe pin  58 . When the waiting fail safe system  54  is disengaged (operating under non-failure conditions) the waiting fail safe pin  58  does not contact the waiting fail safe lug  56  within the pin hole  60 , but instead, has a clearance  62 , which maintains a substantially circumferential space between the waiting fail safe pin  58  and the waiting fail safe lug  56 . The clearance  62  may be achieved due to the diameter of the pin hole  60  being suitably larger than the outside diameter of the waiting fail safe pin  58  and due to the design length of the first and second primary forward mount links  44 ,  46 , which carry the engine load under non-failure conditions. Moreover, the clearance  62  is sized by a number of factors including, but not limited to, the tolerance, the thermal operating conditions, and the mechanical load of the engine, to ensure the waiting fail safe lug  56  does not carry any load under non-failure conditions. 
         [0041]    Furthermore, the waiting fail safe lug  56  may include a trigger system  64 . The trigger system  64  may include a J-shaped trigger  66 , a spring  68 , and a slider block  70 , which may slide operatively along a channel  72  in a direction that is substantially perpendicular to the longitudinal central axis  20  (shown in  FIG. 1 ). The slider block  70  may be substantially rectangular in shape and may include a narrow portion  74  and a clearance-filling portion  76 , which may have a notch  78 . The channel  72  may include an end wall  80  at one end and an open guide portion  82  at the opposite end. Moreover, the channel  72  may be formed on the waiting fail safe lug  56  at a position that may be between the pin hole  60  and the fan case  34 . When the waiting fail safe system  54  is disengaged (as shown in  FIG. 7 ), the slider block  70  may be oriented within the channel  72  so that the clearance-filling portion  76  may be adjacent to the end wall  80  and the narrow portion  74  may be adjacent to the open guide portion  82 . The spring  68  may be disposed within the channel  72  and may be operatively connected at one end to the end wall  80  and at the opposite end to the clearance-filling portion  76 . 
         [0042]    The J-shaped trigger  66  may be formed of a straight portion  84  and an arcuate portion  86 . An activating nub  88  may be located at the end of the straight portion  84  and a locking catch  90  may be located at the end of the arcuate portion  86 . The arcuate portion  86  may include a pivot section  92 , which may be pivotally joined to the waiting fail safe lug  56  via a pin  94  so that the trigger  66  operatively pivots. 
         [0043]    In the disengaged condition of the waiting fail safe system  54 , the locking catch  90  of the trigger  66  may operatively fit into the notch  78  of the clearance-filling portion  76  so that the slider block  70  may be locked into a position adjacent to the end wall  80  of the channel  72  maintaining the spring  68  in a compressed state. 
         [0044]    In the event of a primary mounting component failure, such as a failure in the primary forward mount links  44 , 46 , the primary forward mount lugs  48 , 50 , or the bolts and nuts  52 , the engine  10  load will shift and the waiting fail safe system  54  will become engaged to alternatively carry the load that was once carried by the primary mounting components. In particular, the shifting of the engine  10  will cause the waiting fail safe pin  58  to engage with the activating nub  88  causing the trigger  66  to pivot at the pivot section  92 . Simultaneously, as the trigger  66  pivots, the locking catch  90  disengages from the notch  78  and the spring  68  uncoils causing the slider block  70  to slide along the channel  72  so that the clearance-filling portion  76  contacts the waiting fail safe pin  58  and closes the clearance  62 , as shown in  FIG. 7 . Accordingly, the clearance-filling portion  76  firmly forces, and securely maintains, the waiting fail safe pin  58  into contact with the surface of the pin hole  60 . In this engaged position, the waiting fail safe system  54  will effectively carry the load level as determined by the static equilibrium. As such, the waiting fail safe system  54  mitigates initial dynamic amplification factor and also restricts repeated dynamic amplification factor by ensuring the engine will not move due to subsequent vertical loads. 
         [0045]      FIG. 9  illustrates a flowchart  900  of a method of configuring an engine mount for a gas turbine engine. Box  910  shows the step of mechanically coupling a trigger system to a lug of a fan case with the trigger system configured for selective engagement of a pin coupled to the engine mount. The trigger system may include a trigger, a spring, a slider block and a channel. The trigger may include an activating nub configured to initiate movement of the trigger system from a disengaged position to an engaged position when the pin contacts the activating nub. The slider block may be configured for selective contact with the pin and may define a notch for operative engagement with the trigger. The trigger system may prevent subsequent movement of the pin when the trigger system is moved to an engaged position. 
         [0046]    Although the waiting fail safe system  54  with the trigger system  64  was described in regards to the forward mount  38 , it should be understood that the waiting fail safe system  54  with the trigger system  64  equally applies to other mounting systems, including the aft mount  40  described above, for mounting gas turbine engines to fuselages, wings or tails of aircrafts. 
         [0047]    While the present disclosure has shown and described details of exemplary embodiments, it will be understood by one skilled in the art that various changes in detail may be effected therein without departing from the spirit and scope of the disclosure as defined by claims supported by the written description and drawings. Further, where these exemplary embodiments (and other related derivations) are described with reference to a certain number of elements it will be understood that other exemplary embodiments may be practiced utilizing either less than or more than the certain number of elements. 
       INDUSTRIAL APPLICABILITY 
       [0048]    Based on the foregoing, it can be seen that the present disclosure sets forth an engine mount including a waiting fail safe system with a trigger system for a gas turbine engine. The teachings of this disclosure can be employed to reduce the dynamic amplification factor of a waiting fail safe system of an engine mount for a gas turbine engine. Specifically, the reduction of the dynamic amplification factor reduces the design load for the waiting fail safe system of the present disclosure and also contributes to overall engine weight reduction. Furthermore, in the event the primary load paths of the engine mount fail the waiting fail safe system with the trigger system will provide an alternative load path while at the same time preventing the engine from movement due to subsequent vertical loads.