Abstract:
A method for servicing a gas turbine engine includes providing access from a forward section of the gas turbine engine to a gearbox contained within a bearing compartment.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present disclosure is a continuation-in-part application of U.S. patent application Ser. No. 13/087,579, filed 15 Apr. 2011, and U.S. patent application Ser. No. 13/275,286, filed 17 Oct. 2011. 
     
    
     BACKGROUND 
       [0002]    The present disclosure relates to a gas turbine engine, and in particular, to a case structure therefor. 
         [0003]    Gas turbine engines typically include one or more rotor shafts that transfer power and rotary motion from a turbine section to a compressor section and fan section. The rotor shafts are supported within an engine static structure which is typically constructed of modules with individual case sections which are joined together at bolted flanges. The flanges form a joint capable of withstanding the variety of loads transmitted through the engine static structure. An ongoing issue for gas turbine engines is the ease and speed at which they can be serviced. 
       SUMMARY 
       [0004]    A method for servicing a gas turbine engine according to an exemplary aspect of the present disclosure includes providing access from a forward section of the gas turbine engine to a gearbox contained within a bearing compartment. 
         [0005]    In a further non-limiting embodiment of the foregoing method for servicing a gas turbine engine, disassembling the bearing compartment may include disassembling a front wall from a front center body support. Additionally or alternatively, access may be provided from the forward section to a flex support mounted within the front center body support, the flex support mounted to the gearbox. Additionally or alternatively, a bearing package may be disassembled from the front center body support. Additionally or alternatively, the front wall may be disassembled from an output shaft driven by the gearbox. 
         [0006]    A method for servicing a gas turbine engine according to another exemplary aspect of the present disclosure may include providing access from a forward section of a front center body assembly to a gearbox driven by a low spool. 
         [0007]    In a further non-limiting embodiment of any of foregoing methods for servicing a gas turbine engine, a fan may be interconnected to the gearbox. Additionally or alternatively, the fan may be disassembled from the geared architecture. 
         [0008]    In a further non-limiting embodiment of any of foregoing methods, a multiple of fasteners located within the forward section of a front center body assembly may be removed to disassemble a front wall from a front center body support of the front center body assembly. Additionally or alternatively, the multiple of fasteners may be located to provide access from the forward section of the gas turbine engine. 
         [0009]    A gas turbine engine according to another exemplary aspect of the present disclosure includes a front center body support defined around an engine axis and a front wall mounted to the front center body support. The front wall is removable from the front center body support to provide access to the gearbox. 
         [0010]    In a further non-limiting embodiment of any of the foregoing gas turbine engine embodiments, the gas turbine engine may define the front center body support about an engine longitudinal axis. 
         [0011]    In a further non-limiting embodiment of any of the foregoing gas turbine engine embodiments, the gas turbine engine may include a seal package mounted to the front center body support. 
         [0012]    In a further non-limiting embodiment of any of the foregoing gas turbine engine embodiments, the gas turbine engine may include a bearing package mounted to the front center body support, and a low spool operable to drive the gearbox. Additionally or alternatively, the front center body support may include a flange which abuts a flange of the front wall. 
         [0013]    In a further non-limiting embodiment of any of the foregoing gas turbine engine embodiments, may include a multiple of fasteners which attach the flange of the front wall to the flange of the front center body support. Additionally or alternatively, the multiple of fasteners may be accessible from a forward section of the gas turbine engine. 
         [0014]    In a further non-limiting embodiment of any of the foregoing gas turbine engine embodiments, the front wall may support a bearing package to support an output shaft driven by the gearbox. Further, the output shaft may be operable to drive a fan. 
         [0015]    In a further non-limiting embodiment of any of the foregoing gas turbine engine embodiments, the gearbox may drive a fan section at a speed different than a speed of a low speed spool. 
         [0016]    In a further non-limiting embodiment of any of the foregoing gas turbine engine embodiments, the front center body may at least partially define a core flow path. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiment. The drawings that accompany the detailed description can be briefly described as follows: 
           [0018]      FIG. 1  is a schematic cross-section of an embodiment of a gas turbine engine; 
           [0019]      FIG. 2  is an enlarged cross-section of a portion of the gas turbine engine which illustrates a front center body assembly; 
           [0020]      FIG. 3  is an enlarged cross-section of the geared architecture of the gas turbine engine; 
           [0021]      FIG. 4  is an exploded perspective view of a front center body assembly; 
           [0022]      FIG. 5  is an enlarged perspective partial cross-section of a front center body support of the front center body assembly; 
           [0023]      FIG. 6  is an enlarged sectional view of the front center body support; 
           [0024]      FIG. 7  is an exploded view of the front center body support; and 
           [0025]      FIG. 8  is a schematic view of a forward gearbox removal from the gas turbine engine. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]      FIG. 1  schematically illustrates a gas turbine engine  20 . The gas turbine engine  20  is disclosed herein as a two-spool turbofan that generally incorporates a fan section  22 , a compressor section  24 , a combustor section  26  and a turbine section  28 . Alternative engines might include an augmentor section (not shown) among other systems or features. The fan section  22  drives air along a bypass flowpath while the compressor section  24  drives air along a core flowpath for compression and communication into the combustor section  26  then expansion through the turbine section  28 . Although depicted as a turbofan gas turbine engine in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are not limited to use with turbofans as the teachings may be applied to other types of turbine engines. 
         [0027]    The engine  20  generally includes a low spool  30  and a high spool  32  mounted for rotation about an engine central longitudinal axis A relative to an engine static structure  36  via several bearing supports  38 . The low spool  30  generally includes an inner shaft  40  that interconnects a fan  42 , a low pressure compressor  44  and a low pressure turbine  46 . The inner shaft  40  drives the fan  42  through a geared architecture  48  to drive the fan  42  at a lower speed than the low spool  30 . The high spool  32  includes an outer shaft  50  that interconnects a high pressure compressor  52  and high pressure turbine  54 . A combustor  56  is arranged between the high pressure compressor  52  and the high pressure turbine  54 . The inner shaft  40  and the outer shaft  50  are concentric and rotate about the engine central longitudinal axis A which is collinear with their longitudinal axes. 
         [0028]    Core airflow is compressed by the low pressure compressor  44  then the high pressure compressor  52 , mixed with the fuel and burned in the combustor  56 , then expanded over the high pressure turbine  54  and low pressure turbine  46 . The turbines  54 ,  46  rotationally drive the respective low spool  30  and high spool  32  in response to the expansion. 
         [0029]    The main engine shafts  40 ,  50  are supported at a plurality of points by the bearing system  38  within the static structure  36 . In one non-limiting embodiment, bearing system  38  includes a #2 bearing support  38 A located within the compressor section  24 . 
         [0030]    With reference to  FIG. 2 , the engine static structure  36  proximate the compressor section  24  includes a front center body assembly  60  adjacent a #2 bearing support  38 A. The front center body assembly  60  generally includes a front center body support  62 . The #2 bearing support  38 A generally includes a seal package  64 , a bearing package  66 , a flex support  68  and a centering spring  70 . 
         [0031]    With reference to  FIG. 3 , the flex support  68  provides a flexible attachment of the geared architecture  48  within the front center body support  62  (also illustrated in  FIG. 4 ). The flex support  68  reacts the torsional loads from the geared architecture  48  and facilitates vibration absorption as well as other support functions. The centering spring  70  is a generally cylindrical cage-like structural component with a multiple of beams which extend between flange end structures (also illustrated in  FIG. 4 ). The centering spring  70  resiliently positions the bearing package  66  with respect to the low spool  30 . In one embodiment, the beams are double-tapered beams arrayed circumferentially to control a radial spring rate that may be selected based on a plurality of considerations including, but not limited to, bearing loading, bearing life, rotor dynamics, and rotor deflection considerations. 
         [0032]    The front center body support  62  includes a front center body section  72  and a bearing section  74  defined about axis A with a frustro-conical interface section  76  therebetween ( FIG. 5 ). The front center body section  72  at least partially defines the core flowpath into the low pressure compressor  44 . The front center body section  72  includes an annular core passage with a multiple of front center body vanes  72 A,  72 B. The bearing section  74  is defined radially inward of the front center body section  72 . The bearing section  74  locates the bearing package  66  and the seal package  64  with respect to the low spool  30 . The frustro-conical interface section  76  combines the front center body section  72  and the bearing section  74  to form a unified load path, substantially free of kinks typical of a conventional flange joint, from the bearing package  66  to the outer periphery of the engine static structure  36 . The frustro-conical interface section  76  may include a weld W ( FIG. 5 ) or, alternatively, be an integral section such that the front center body support  62  is a unitary component. 
         [0033]    The integral, flange-less arrangement of the frustro-conical interface section  76  facilitates a light weight, reduced part count architecture with an increased ability to tune the overall stiffness and achieve rotor dynamic requirements. Such an architecture also further integrates functions such as oil and air delivery within the bearing compartment which surrounds bearing package  66 . 
         [0034]    With reference to  FIG. 6 , the front center body support  62  includes mount features to receive the flex support  68 . In one disclosed non-limiting embodiment, the mount features of the front center body support  62  includes an internal spline  78  and a radial inward directed fastener flange  80  on the front center body section  72 . The flex support  68  includes a corresponding outer spline  82  and radially outwardly directed fastener flange  84 . The flex support  68  is received into the front center body support  62  at a splined interface  86  formed by splines  78 ,  82  and retained therein such that fastener flange  84  abuts fastener flange  80 . A set of fasteners  88  such as bolts are threaded into the fastener flanges  80 ,  84  to mount the flex support  68  within the front center body support  62 . 
         [0035]    With reference to  FIG. 7 , the fasteners  88  are directed forward to provide access from a forward section of the front center body assembly  60  opposite the bearing package  66  of the number two bearing system  38 A. The fasteners  88  are thereby readily removed to access a gearbox  90  of the geared architecture  48 . 
         [0036]    A front wall  102  aft of the fan  42  is mounted to a forward section of the front center body support  62  to provide access to the geared architecture  48  from the front of the engine  20 . The front wall  102  includes a flange  103  mountable to the front center body support  62  at the flange  60  by a multiple of fasteners  105 , which fasteners  105  may in one non-limiting embodiment be bolts. The front wall  102  and the front center body support  62  define a bearing compartment  100  (also shown in  FIG. 2 ) which mounts to the bearing package  66 . The front wall  102  is removable such that the gearbox  90  may be accessed as a module. The gearbox  90  may thereby be accessed to facilitate rapid on-wing service. 
         [0037]    It should be appreciated that various bearing structures  104  (illustrated schematically and in  FIG. 2 ) and seals  106  (illustrated schematically and in  FIG. 2 ) may be supported by the front wall  102  to contain oil and support rotation of an output shaft  108 . The output shaft  108  connects with the geared architecture  48  to drive the fan  42 . Fan blades  42 B extend from a fan hub  110  which are mounted to the output shaft  108  for rotation therewith. It should be appreciated that the bearing structures  104  and seals  106  may, in the disclosed non-limiting embodiment may be disassembled with the front wall  102  as a unit after removal of the fan hub  110 . 
         [0038]    The gearbox  90  is driven by the low spool  30  ( FIG. 1 ) through a coupling shaft  112 . The coupling shaft  112  transfers torque through the bearing package  66  to the gearbox  90  as well as facilitates the segregation of vibrations and other transients. The coupling shaft  112  generally includes a forward coupling shaft section  114  and an aft coupling shaft section  116  which extends from the bearing package  66 . The forward coupling shaft section  114  includes an interface spline  118  which mates with an aft spline  120  of the aft coupling shaft section  116 . An interface spline  122  of the aft coupling shaft section  116  connects the coupling shaft  112  to the low spool  30  through, in this non limiting embodiment, splined engagement with a spline  124  on a low pressure compressor hub  126  of the low pressure compressor  44 . 
         [0039]    To remove the gearbox  90 , the fan hub  110  is disassembled from the output shaft  108 . The multiple of fasteners  105  are then removed such that the front wall  102  is disconnected from the front center body support  62 . The multiple of fasteners  88  are then removed from the front of the engine  20 . The geared architecture  48  is then slid forward out of the front center body support  62  such that the interface spline  118  is slid off the aft spline  120  and the outer spline  82  is slid off the internal spline  78 . The geared architecture  48  is thereby removable from the engine  20  as a module ( FIG. 8 ; illustrated schematically). It should be appreciated that other componentry may need to be disassembled to remove the geared architecture  48  from the engine  20 , however, such disassembly is relatively minor and need not be discussed in detail. It should be further appreciated that other components such as the bearing package  66  and seal  64  are also now readily accessible from the front of the engine  20 . 
         [0040]    Removal of the gearbox  90  from the front of the engine  20  as disclosed saves significant time and expense. The geared architecture  48 , is removable from the engine  20  as a module and does not need to be further disassembled. Moreover, although the geared architecture  48  must be removed from the engine to gain access to the bearing package  66  and the seal  64 , the geared architecture  48  does not need to be removed from the engine  20  to gain access to the engine core itself. 
         [0041]    It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit herefrom. 
         [0042]    Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present invention. 
         [0043]    Although the different examples have specific components shown in the illustrations, embodiments of this invention are not limited to those particular combinations. It is possible to use some of the components or features from one of the examples in combination with features or components from another one of the examples. 
         [0044]    The foregoing description is exemplary rather than defined by the limitations within. Various non-limiting embodiments are disclosed herein, however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced other than as specifically described. For that reason the appended claims should be studied to determine true scope and content.