Abstract:
The variable pitch propeller assembly includes a hub. The variable pitch propeller assembly also includes a plurality of propeller blade assemblies spaced circumferentially about the hub. Each of the plurality of propeller blade assemblies configured to rotate a respective propeller blade. The variable pitch propeller assembly also includes a hydraulic fluid port assembly integrally formed and including at least three hydraulic fluid ports configured to receive respective flows of hydraulic fluid from a stationary hydraulic fluid transfer sleeve. The variable pitch propeller assembly also includes a pitch actuator assembly coupled in flow communication with at least three hydraulic fluid ports through respective hydraulic fluid transfer tubes. The pitch actuator coupled to the plurality of propeller blade assemblies to selectively control a pitch of the propeller blades. The pitch actuator assembly includes a travel stop configured to limit a rotation of at least one of the pitch actuator assemblies.

Description:
BACKGROUND 
       [0001]    The field of the disclosure relates generally to gas turbine engines and, more particularly, to a method and system for supplying hydraulic fluid to an integrated pitch control mechanism (PCM) actuator. 
         [0002]    Gas turbine engines typically include a fan assembly that provides air to a core engine and compresses the air to generate thrust. At least some known fan assemblies include variable pitch fan blades that are controlled by externally modulated flows of hydraulic fluid. Fan blade pitch controls the performance of the fan, so it may be optimized at various aircraft conditions. Fan pitch is typically controlled by hydraulic fluid transfer from a stationary supply system to a rotating actuator. At least some known gas turbine engines use an intermediate tubing mechanism to supply hydraulic fluid to the rotating actuator from the stationary supply system. Intermediate tubing mechanisms add weight to the aircraft and occupy valuable space on the engine. 
       BRIEF DESCRIPTION 
       [0003]    In one aspect, a variable pitch propeller assembly is provided. The variable pitch propeller assembly includes a hub rotatable about a shaft having an axis of rotation. The variable pitch propeller assembly also includes a plurality of propeller blade assemblies spaced circumferentially about the hub. Each of the plurality of propeller blade assemblies configured to rotate a respective propeller blade about a radially extending pitch axis of rotation. The variable pitch propeller assembly also includes a hydraulic fluid port assembly integrally formed and rotatable with the shaft. The hydraulic fluid port assembly includes at least three hydraulic fluid ports configured to receive respective flows of hydraulic fluid from a stationary hydraulic fluid transfer sleeve at least partially surrounding the port assembly. The variable pitch propeller assembly also includes a pitch actuator assembly coupled in flow communication with at least three hydraulic fluid ports through respective hydraulic fluid transfer tubes extending axially from the hydraulic fluid port assembly to the pitch actuator. The pitch actuator coupled to the plurality of propeller blade assemblies to selectively control a pitch of the propeller blades. The pitch actuator assembly includes a travel stop configured to limit a rotation of at least one of the pitch actuator assemblies and the plurality of propeller blade assemblies. 
         [0004]    In another aspect, a method of operating a variable pitch fan selectively controlled using an integrated pitch control mechanism (PCM) actuator assembly is provided. The PCM assembly includes a stationary to rotary fluid transfer assembly and a PCM actuator formed as an integral device. The method includes channeling a plurality of flows of hydraulic fluid between a source of modulated hydraulic fluid and a stationary transfer member of the stationary to rotary fluid transfer assembly. The method also includes directing the plurality of flows of hydraulic fluid across a gap between the stationary transfer member and a rotatable transfer member of the stationary to rotary fluid transfer assembly. The method also includes channeling the plurality of flows of hydraulic fluid to an actuation cavity of the PCM actuator. The method also includes selectively moving an actuation member of the PCM actuator based on relative pressures of the plurality of flows of hydraulic fluid. 
         [0005]    In yet another aspect, a variable pitch turbofan gas turbine engine is provided. The variable pitch turbofan gas turbine engine includes a core engine including a multistage compressor and a fan assembly comprising an axis of rotation and powered by the core engine. The fan assembly includes a hub rotatable about a shaft having an axis of rotation. The fan assembly also includes a plurality of propeller blade assemblies spaced circumferentially about the hub. Each of the plurality of propeller blade assemblies configured to rotate a respective propeller blade about a radially extending pitch axis of rotation. The fan assembly also includes a hydraulic fluid port assembly integrally formed and rotatable with the shaft. The hydraulic fluid port assembly includes at least three hydraulic fluid ports configured to receive respective flows of hydraulic fluid from a stationary hydraulic fluid transfer sleeve at least partially surrounding the port assembly. The fan assembly also includes a pitch actuator assembly coupled in flow communication with the at least three hydraulic fluid ports through respective hydraulic fluid transfer tubes extending axially from the hydraulic fluid port assembly to the pitch actuator. The pitch actuator coupled to the plurality of propeller blade assemblies to selectively control a pitch of the propeller blades. The pitch actuator assembly includes a travel stop configured to limit a rotation of at least one of the pitch actuator assemblies and the plurality of propeller blade assemblies. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
           [0007]      FIGS. 1-12  show example embodiments of the method and apparatus described herein. 
           [0008]      FIG. 1  is a schematic view of an exemplary gas turbine engine. 
           [0009]      FIG. 2  is a side elevation view of a gas turbine engine fan rotor assembly including a PCM actuator assembly. 
           [0010]      FIG. 3  is an exploded view of an integrated PCM actuator assembly. 
           [0011]      FIG. 4 a    is a perspective view of a pitch actuator.  FIG. 4 b    is a cutaway perspective view of a pitch actuator. 
           [0012]      FIG. 5 a    is a perspective view of an actuator shell, a hydraulic fluid transfer sleeve, and an end cap.  FIG. 5 b    is a cutaway perspective view of an actuator shell, a hydraulic fluid transfer sleeve, and an end cap. 
           [0013]      FIGS. 6 a  and 6 b    are axial views of the integrated PCM actuator assemblies shown in  FIGS. 3, 4, 5, and 7  along lines  6 - 6  in  FIGS. 4, 5, and 7 .  FIG. 6 a    is an axial view of the integrated PCM actuator assembly in a normal operational embodiment.  FIG. 6 b    is an axial view of the integrated PCM actuator assembly in a decreased pitch operational embodiment. 
           [0014]      FIG. 7  is a side elevation view of an integrated PCM actuator assembly. 
           [0015]      FIG. 8  is an overlay of the internal flow passages of an actuator shell on a pitch actuator. 
           [0016]      FIGS. 9 a  and 9 b    are axial views of the integrated PCM actuator assembly shown in  FIGS. 3, 4, 5, and 7  along lines  9 - 9  in  FIGS. 4, 5, and 7 .  FIG. 9 a    depicts a normal operational embodiment of integrated PCM actuator.  FIG. 9 b    depicts a decreased pitch operational embodiment of integrated PCM actuator assembly. 
           [0017]      FIG. 10  is a diagram of an increase flow path, a decrease flow path, and a drain flow path within integrated PCM actuator assembly with radial gap transfer. 
           [0018]      FIG. 11  is a side elevation view of an integrated PCM actuator assembly with axial gap transfer. 
           [0019]      FIG. 12  is a diagram of an increase flow path, a decrease flow path, and a drain flow path within integrated PCM actuator assembly with axial gap transfer. 
       
    
    
       [0020]    Although specific features of various embodiments may be shown in some drawings and not in others, this is for convenience only. Any feature of any drawing may be referenced and/or claimed in combination with any feature of any other drawing. 
         [0021]    Unless otherwise indicated, the drawings provided herein are meant to illustrate features of embodiments of the disclosure. These features are believed to be applicable in a wide variety of systems comprising one or more embodiments of the disclosure. As such, the drawings are not meant to include all conventional features known by those of ordinary skill in the art to be required for the practice of the embodiments disclosed herein. 
       DETAILED DESCRIPTION 
       [0022]    In the following specification and the claims, reference will be made to a number of terms, which shall be defined to have the following meanings. 
         [0023]    The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise. 
         [0024]    “Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not. 
         [0025]    Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about”, “approximately”, and “substantially”, are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and/or interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. 
         [0026]    The following detailed description illustrates embodiments of the disclosure by way of example and not by way of limitation. It is contemplated that the disclosure has general application to a method and system for supplying hydraulic fluid to an integrated PCM actuator assembly. 
         [0027]    Embodiments of the integrated PCM actuator assembly hydraulic fluid supply system described herein provide hydraulic fluid to an integrated PCM actuator assembly of a gas turbine engine. The integrated PCM actuator assembly hydraulic fluid supply system includes a stationary hydraulic fluid transfer sleeve circumscribing a hydraulic fluid port assembly which includes a plurality of hydraulic fluid ports. A fan blade pitch change actuator assembly is coupled in flow communication with the hydraulic fluid port assembly. The stationary hydraulic fluid transfer sleeve is configured to deliver a flow of hydraulic fluid to the hydraulic fluid port assembly which actuates the pitch actuator assembly and controls the pitch of fan blades with the gas turbine engine. 
         [0028]    The integrated PCM actuator assembly hydraulic fluid supply system described herein offers advantages over known methods of supplying hydraulic fluid to an integrated PCM actuator assembly. More specifically, the integrated PCM actuator assembly described herein supplies hydraulic fluid directly to the actuator. Supplying hydraulic fluid directly to the actuator in the integrated PCM actuator assembly decreases the weight of the actuator and the engine by eliminating additional mechanical parts. Furthermore, integrating the hydraulic fluid supply system into the actuator can improve reliability of the actuator. 
         [0029]      FIG. 1  is a schematic cross-sectional view of a gas turbine engine in accordance with an exemplary embodiment of the present disclosure. In the example embodiment, the gas turbine engine is a high-bypass turbofan jet engine  10 , referred to herein as “turbofan engine  10 .” As shown in  FIG. 1 , turbofan engine  10  defines an axial direction A (extending parallel to a longitudinal centerline  12  provided for reference) and a radial direction R. In general, turbofan engine  10  includes a fan section  14  and a core turbine engine  16  disposed downstream from fan section  14 . 
         [0030]    The exemplary core turbine engine  16  depicted generally includes a substantially tubular outer casing  18  that defines an annular inlet  20 . Outer casing  18  encases, in serial flow relationship, a compressor section including a booster or low pressure (LP) compressor  22  and a high pressure (HP) compressor  24 ; a combustion section  26 ; a turbine section including a high pressure (HP) turbine  28  and a low pressure (LP) turbine  30 ; and a jet exhaust nozzle section  32 . A high pressure (HP) shaft or spool  34  drivingly connects HP turbine  28  to HP compressor  24 . A low pressure (LP) shaft or spool  36  drivingly connects LP turbine  30  to LP compressor  22 . The compressor section, combustion section  26 , turbine section, and nozzle section  32  together define a core air flowpath  37 . 
         [0031]    For the embodiment depicted, fan section  14  includes a variable pitch fan  38  having a plurality of fan blades  40  coupled to a disk  42  in a spaced apart manner. As depicted, fan blades  40  extend outwardly from disk  42  generally along radial direction R. Each fan blade  40  is rotatable relative to disk  42  about a pitch axis P by virtue of fan blades  40  being operatively coupled to a suitable pitch change mechanism  44  configured to collectively vary the pitch of fan blades  40  in unison. Fan blades  40 , disk  42 , and pitch change mechanism  44  are together rotatable about longitudinal axis  12  by LP shaft  36  across a power gear box  46 . Power gear box  46  includes a plurality of gears for adjusting the rotational speed of fan  38  relative to LP shaft  36  to a more efficient rotational fan speed. 
         [0032]    Referring still to the exemplary embodiment of  FIG. 1 , disk  42  is covered by a rotatable front hub  48  aerodynamically contoured to promote an airflow through plurality of fan blades  40 . Additionally, exemplary fan section  14  includes an annular fan casing or outer nacelle  50  that circumferentially surrounds fan  38  and/or at least a portion of core turbine engine  16 . It should be appreciated that nacelle  50  may be configured to be supported relative to core turbine engine  16  by a plurality of circumferentially-spaced outlet guide vanes  52 . Moreover, a downstream section  54  of nacelle  50  may extend over an outer portion of core turbine engine  16  so as to define a bypass airflow passage  56  therebetween. 
         [0033]    During operation of turbofan engine  10 , a volume of air  58  enters turbofan engine  10  through an associated inlet  60  of nacelle  50  and/or fan section  14 . As volume of air  58  passes across fan blades  40 , a first portion of air  58  as indicated by arrows  62  is directed or routed into bypass airflow passage  56  and a second portion of air  58  as indicated by arrow  64  is directed or routed into core air flowpath  37 , or more specifically into LP compressor  22 . The ratio between first portion of air  62  and second portion of air  64  is commonly known as a bypass ratio. The pressure of second portion of air  64  is then increased as it is routed through high pressure (HP) compressor  24  and into combustion section  26 , where it is mixed with fuel and burned to provide combustion gases  66 . 
         [0034]    Combustion gases  66  are routed through HP turbine  28  where a portion of thermal and/or kinetic energy from combustion gases  66  is extracted via sequential stages of HP turbine stator vanes  68  that are coupled to outer casing  18  and HP turbine rotor blades  70  that are coupled to HP shaft or spool  34 , thus causing HP shaft or spool  34  to rotate, thereby supporting operation of HP compressor  24 . Combustion gases  66  are then routed through LP turbine  30  where a second portion of thermal and kinetic energy is extracted from combustion gases  66  via sequential stages of LP turbine stator vanes  72  that are coupled to outer casing  18  and LP turbine rotor blades  74  that are coupled to LP shaft or spool  36 , thus causing LP shaft or spool  36  to rotate, thereby supporting operation of LP compressor  22  and/or rotation of fan  38 . 
         [0035]    Combustion gases  66  are subsequently routed through jet exhaust nozzle section  32  of core turbine engine  16  to provide propulsive thrust. Simultaneously, the pressure of first portion of air  62  is substantially increased as first portion of air  62  is routed through bypass airflow passage  56  before it is exhausted from a fan nozzle exhaust section  76  of turbofan engine  10 , also providing propulsive thrust. HP turbine  28 , LP turbine  30 , and jet exhaust nozzle section  32  at least partially define a hot gas path  78  for routing combustion gases  66  through core turbine engine  16 . 
         [0036]    It should be appreciated, however, that exemplary turbofan engine  10  depicted in  FIG. 1  is by way of example only, and that in other exemplary embodiments, turbofan engine  10  may have any other suitable configuration. It should also be appreciated, that in still other exemplary embodiments, aspects of the present disclosure may be incorporated into any other suitable gas turbine engine. For example, in other exemplary embodiments, aspects of the present disclosure may be incorporated into, e.g., a turboprop engine and unducted fan engine. 
         [0037]      FIG. 2  is a side elevation view of a fan rotor assembly  200  including an integrated PCM actuator assembly  202  in accordance with an exemplary embodiment of the present disclosure. Fan rotor assembly  200  includes integrated PCM actuator assembly  202 , an epicyclic gearbox  204 , a power engine rotor  206 , a stationary hydraulic fluid transfer sleeve  208 , and a hub assembly  210 . Hub assembly  210  includes a unison ring  212 , a plurality of fan blade trunnion yokes  214 , a plurality of trunnion assemblies  216 , and a plurality of fan blades  218 . In some embodiments, LP shaft  36  (shown in  FIG. 1 ) is fixedly coupled to epicyclic gearbox  204  which is rotationally coupled to power engine rotor  206 . Power engine rotor  206  is rotationally coupled to hub assembly  210  and integrated PCM actuator assembly  202  which is rotationally coupled to unison ring  212  through integrated PCM actuator assembly  202 . Hub assembly  210  is rotationally coupled to fan blades  218 . Unison rings  212  are rotationally coupled to fan blade trunnion yokes  214  which are rotationally coupled to trunnion assemblies  216 . Trunnion assemblies  216  are rotationally coupled to fan blades  218 . Stationary hydraulic fluid transfer sleeve  208  is coupled to supports (not shown) within epicyclic gearbox  204  and circumscribes integrated PCM actuator assembly  202 . Stationary hydraulic fluid transfer sleeve  208  is coupled in flow communication with integrated PCM actuator assembly  202 . 
         [0038]    In operation, LP shaft  36  (shown in  FIG. 1 ) is configured to rotate a plurality of gears (not shown) within epicyclic gearbox  204  which are configured to rotate power engine rotor  206 . Power engine rotor  206  is configured to rotate integrated PCM actuator assembly  202  which is configured to rotate unison rings  212 . Unison ring  212  is configured to rotate fan blade trunnion yokes  214  which are configured to rotate trunnion assemblies  216 . Trunnion assemblies  216  are configured to rotate fan blades  218  about their respective axis. Stationary hydraulic fluid transfer sleeve  208  is configured to remain stationary while integrated PCM actuator assembly  202  is configured to rotate along with the fan module. 
         [0039]    Stationary hydraulic fluid transfer sleeve  208  is coupled in flow communication with integrated PCM actuator assembly  202 . Hydraulic fluid pressure from stationary hydraulic fluid transfer sleeve  208  actuates integrated PCM actuator assembly  202  which rotates unison ring  212  about a radially extending pitch axis of rotation  220 . Unison ring  212  translates fan blade trunnion yokes  214  along an arcuate path, which rotate respective trunnion assemblies  216  about radially extending pitch axis of rotation  220 . Trunnion assemblies  216  are configured to rotate fan blades  218  about radially extending pitch axis of rotation  220 . 
         [0040]      FIG. 3  is an exploded view of an integrated PCM actuator assembly  300  in accordance with an exemplary embodiment of the present disclosure. Integrated PCM actuator assembly  300  receives hydraulic fluid through a radial gap transfer. Integrated PCM actuator assembly  300  includes an actuator shell  302 , a hydraulic fluid transfer sleeve  304 , a pitch actuator  306 , and an end cap  308 . Actuator shell  302  includes a hydraulic fluid port assembly  310  extending aft in axial direction A from actuator shell  302 . Hydraulic fluid transfer sleeve  304  circumscribes hydraulic fluid port assembly  310 . Actuator shell  302  partially circumscribes pitch actuator  306  which includes a pitch actuator shaft  312  extending forward in axial direction A from pitch actuator  306  through end cap  308  to unison rings  212  (shown in  FIG. 2 ). End cap  308  is coupled to the axially forward end of actuator shell  302 . 
         [0041]      FIG. 4  is two perspective views of a pitch actuator  400 .  FIG. 4 a    is a perspective view of pitch actuator  400 .  FIG. 4 b    is a cutaway perspective view of pitch actuator  400 . Pitch actuator  400  includes a plurality of pitch actuator vanes  404  extending radially outward from pitch actuator shaft  402  and a mechanical transfer range limiter  406  extending aft in axial direction A from pitch actuator  400 . Pitch actuator  400  also includes a pitch actuator void  408  extending through pitch actuator shaft  402 . 
         [0042]      FIG. 5  is two perspective views of an actuator shell  502 , a hydraulic fluid transfer sleeve  504 , and an end cap  506 .  FIG. 5 a    is a perspective view of actuator shell  502 , hydraulic fluid transfer sleeve  504 , and end cap  506 .  FIG. 5 b    is a cutaway perspective view of actuator shell  502 , hydraulic fluid transfer sleeve  504 , and end cap  506 . Actuator shell  502  includes an actuator cap  508  coupled to the axially aft end of actuator shell  502 . Hydraulic fluid port assembly  510  extends aft in axial direction A from actuator cap  508  and is circumscribed by hydraulic fluid transfer sleeve  504 . Actuator shell  502  also includes a plurality of actuator shell vanes  512  extending radially inward from actuator shell  502 . 
         [0043]      FIGS. 6 a  and 6 b    are axial views of the integrated PCM actuator assembly  300  shown in  FIGS. 3, 4, 5, and 7  along lines  6 - 6  in  FIGS. 4, 5, and 7 .  FIG. 6 a    is an axial view of the integrated PCM actuator assembly  300  in a non-mechanically limited position.  FIG. 6 b    is an axial view of the integrated PCM actuator  300  in a mechanically limited position.  FIGS. 6 a  and 6 b    introduce the structure of integrated PCM actuator assembly  300  with pitch actuator  400  disposed within actuator shell  502 .  FIGS. 6 a  and 6 b    will also be discussed with the operational embodiments of integrated PCM actuator assembly  300 . 
         [0044]    Pitch actuator vanes  404  extend radially outward from pitch actuator  400  to an inner radial surface  514  of actuator shell  502 . Actuator shell vanes  512  extend radially inward from actuator shell  502  to an outer radial surface  410  of pitch actuator  400 . Each actuator shell vane  512  extends between two pitch actuator vanes  404  forming an alternating circumferential pattern of actuator shell vanes  512  and pitch actuator vanes  404 . A decrease cavity  602  and an increase cavity  604  are formed from the volume between actuator shell vanes  512  and pitch actuator vanes  404 . Each actuator shell vane  512  is adjacent to decrease cavity  602  on one side and increase cavity  604  on the other side. 
         [0045]      FIG. 7  is a side elevation view of an integrated PCM actuator assembly  300  in accordance with an exemplary embodiment of the present disclosure.  FIG. 8  is an overlay of the internal flow passages of actuator shell  502  on pitch actuator  400 .  FIGS. 9 a  and 9 b    are axial views of the integrated PCM actuator assembly shown in  FIGS. 3, 4, 5, and 8  along lines  9 - 9  in  FIGS. 4, 5, and 8 .  FIG. 9 a    depicts a normal operational embodiment of integrated PCM actuator assembly  300 .  FIG. 9 b    depicts a decreased pitch operational embodiment of integrated PCM actuator assembly  300 .  FIG. 10  is a diagram of an increase flow path  610 , a decrease flow path  630 , and a drain flow path  650  within integrated PCM actuator assembly  300 . Increase flow path  610 , decrease flow path  630 , and drain flow path  650  are described below with reference to  FIGS. 7-10 . The internal flow passages are shown with increased clarity in  FIG. 8  with removal of the outer casing. The ports that feed the internal passages are best depicted in  FIGS. 6 a  and 6 b   , which have previously been discussed.  FIGS. 9 a  and 9 b    demonstrate that the supply lines are oriented to create fail safes. Finally,  FIG. 10  presents a high level schematic of increase flow path  610 , decrease flow path  630 , and drain flow path  650 . A hydraulic fluid supply system  516  supplies hydraulic fluid to all flow paths. 
         [0046]    Increase flow path  610  includes a stationary increase delivery tube  612  coupled in flow communication with hydraulic fluid supply system  516  and hydraulic fluid transfer sleeve  504 . A rotating increase delivery channel  614  is disposed within hydraulic fluid port assembly  510  and receives hydraulic fluid from stationary increase delivery tube  612 . Rotating increase delivery channel  614  directs hydraulic fluid to an increase actuator passage  616  disposed within hydraulic fluid port assembly  510  and actuator cap  508 . Increase actuator passage  616  is coupled in flow communication with an increase actuator cap delivery channel  618 . Increase actuator cap delivery channel  618  channels hydraulic fluid circumferentially around actuator cap  508  and is coupled in flow communication with a plurality of increase actuator vane passages  620  which extend forward in axial direction A through actuator vanes  512 . Increase actuator vane passages  620  channels hydraulic fluid to a plurality of increase delivery tubes  622  which deliver hydraulic fluid to increase cavities  604 . Hydraulic fluid delivered to increase cavities  604  increases the hydraulic fluid pressure in increase cavities  604 . Increased hydraulic fluid pressure in increase cavities  604  increases the hydraulic fluid pressure on one side of pitch actuator vanes  404  which rotates pitch actuator  400  and rotate unison ring  212 . 
         [0047]    Decrease flow path  630  includes a stationary decrease delivery tube  632  coupled in flow communication with hydraulic fluid supply system  516  and hydraulic fluid transfer sleeve  504 . A rotating decrease delivery channel  634  is disposed within hydraulic fluid port assembly  510  and receives hydraulic fluid from stationary decrease delivery tube  632 . Rotating decrease delivery channel  634  directs hydraulic fluid to a decrease actuator passage  636  disposed within hydraulic fluid port assembly  510  and actuator cap  508 . Decrease actuator passage  636  is coupled in flow communication with mechanical transfer range limiter  406 . Mechanical transfer range limiter  406  channels hydraulic fluid to a decrease range limiter channel  638  which channels hydraulic fluid to a decrease actuator cap delivery channel  640 . Decrease actuator cap delivery channel  640  channels hydraulic fluid circumferentially around actuator cap  508  and is coupled in flow communication with a plurality of decrease actuator vane passages  642  which extend forward in axial direction A through actuator vanes  512 . Decrease actuator vane passages  642  channels hydraulic fluid to a plurality of decrease delivery tubes  644  which deliver hydraulic fluid to decrease cavities  602 . 
         [0048]    The flow of hydraulic fluid in drain flow path  650  is bidirectional. Drain flow path  650  can deliver hydraulic fluid to decrease cavities  602  from hydraulic fluid supply system  516  or can deliver hydraulic fluid to hydraulic fluid supply system  516  from decrease cavities  602 . During normal operations drain flow path  650  is not pressurized with hydraulic fluid. Drain flow path  650  includes a stationary drain delivery tube  652  coupled in flow communication with hydraulic fluid supply system  516  and hydraulic fluid transfer sleeve  504 . A rotating drain delivery channel  654  is disposed within hydraulic fluid port assembly  510  and receives hydraulic fluid from stationary drain delivery tube  652 . Rotating drain delivery channel  654  directs hydraulic fluid to a decrease actuator passage  656  disposed within hydraulic fluid port assembly  510  and actuator cap  508 . Drain actuator passage  656  is coupled in flow communication with mechanical transfer range limiter  406 . Mechanical transfer range limiter  406  channels hydraulic fluid to a drain range limiter channel  658  which channels hydraulic fluid to a drain actuator cap delivery channel  660 . Drain actuator cap delivery channel  660  channels hydraulic fluid circumferentially around actuator cap  508  and is coupled in flow communication with a plurality of drain actuator vane passages  662  which extend forward in axial direction A through actuator vanes  512 . Drain actuator vane passages  662  channels hydraulic fluid to a plurality of drain delivery tubes  664  which deliver hydraulic fluid to decrease cavities  602 . 
         [0049]      FIG. 6 a    depicts a normal operational embodiment of integrated PCM actuator assembly  300 . The hydraulic fluid pressure on both sides of pitch actuator vanes  404  are equal and the volumes of increase cavity  604  and decrease cavity  602  are also equal. Pitch actuator  400  is not rotated and unison rings  212  are not rotated.  FIG. 6 b    depicts a decreased pitch operational embodiment of integrated PCM actuator assembly  300 . The hydraulic fluid pressure in decrease cavity  602  is increased by the introduction of hydraulic fluid to decrease flow path  630 . Increased hydraulic fluid pressure in decrease cavities  602  increases the hydraulic fluid pressure on one side of pitch actuator vanes  404  which rotates pitch actuator  400  and rotate unison ring  212 . 
         [0050]      FIG. 9 a    depicts a normal operational embodiment of integrated PCM actuator assembly  300 . Mechanical transfer range limiter  406  is in flow communication with decrease actuator passage  636  and decrease range limiter channel  638 . Hydraulic fluid is channeled through decrease flow passage  630  as previously discussed. As pitch actuator  400  rotates further from normal operating position, mechanical transfer range limiter  406  rotates away from flow communication from decrease actuator passage  636  and into flow communication with drain actuator passage  656 .  FIG. 9 b    depicts a decreased pitch operational embodiment of integrated PCM actuator assembly  300 . During normal operations, drain flow path  650  is not pressurized. When mechanical transfer range limiter  406  rotates into flow communication with drain actuator passage  656  and drain range limiter channel  658 , pressurized hydraulic fluid drains from decrease cavity  602  into drain flow path  650  as previously discussed. Hydraulic fluid drains from decrease cavity  602  to hydraulic fluid supply system  516 . Draining hydraulic fluid from decrease cavity  602  decreases the hydraulic fluid pressure in decrease cavity  602  which halts the rotation of pitch actuator  400  in the decrease direction. As pitch actuator  400  rotates further in the opposite direction, mechanical transfer range limiter  406  rotates away from flow communication from drain actuator passage  656  and into flow communication with decrease actuator passage  636 , allowing once again for rotation in both directions. 
         [0051]      FIG. 11  is a side elevation view of an integrated PCM actuator assembly  700  in accordance with an exemplary embodiment of the radial gap transfer of the present disclosure. Integrated PCM actuator assemblies  300  and  700  are the same item except integrated PCM actuator assembly  300  receives hydraulic fluid through an axial gap transfer while integrated PCM actuator assembly  700  receives hydraulic fluid through a radial gap transfer. For clarity, the structural components of integrated PCM actuator assembly  700  are labeled with  700  series numbers while fluid channels and passages within integrated PCM actuator assembly  700  are labeled with  800 ,  900 , and  1000  series numbers (shown with more clarity in  FIG. 12 ). Integrated PCM actuator assembly  700  includes an actuator shell  702 , a hydraulic fluid transfer assembly  704 , a pitch actuator  706 , and an end cap  708 . Hydraulic fluid transfer assembly  704  extends aft in axial direction A from actuator shell  702 . Actuator shell  702  partially circumscribes pitch actuator  706  which includes a pitch actuator shaft  712  extending forward in axial direction A from pitch actuator  706  through end cap  708  to unison rings  212  (shown in  FIG. 2 ). End cap  708  is coupled to the axially forward end of actuator shell  702 . 
         [0052]    Pitch actuator  706  includes a plurality of pitch actuator vanes  714  extending radially outward from pitch actuator shaft  712  and a mechanical transfer range limiter  716  extending aft in axial direction A from pitch actuator  706 . Actuator shell  702  includes an actuator cap  720  coupled to the axially aft end of actuator shell  702 . Actuator shell also includes a plurality of actuator shell vanes  722  extending radially inward from actuator shell  702 . Pitch actuator vanes  714  extend radially outward from pitch actuator  706  to an inner radial surface  724  of actuator shell  706 . Actuator shell vanes  722  extend radially inward from actuator shell  706  to an outer radial surface  726  of pitch actuator  706 . Each actuator shell vane  722  extends between two pitch actuator vanes  714  forming an alternating circumferential pattern of actuator shell vanes  722  and pitch actuator vanes  714 . A decrease cavity (not shown) and an increase cavity (not shown) are formed from the volume between actuator shell vanes  722  and pitch actuator vanes  714 . Each actuator shell vane  722  is adjacent to decrease cavity on one side and increase cavity on the other side. 
         [0053]      FIG. 12  is a diagram of an increase flow path  800 , a decrease flow path  900 , and a drain flow path  1000  within integrated PCM actuator assembly  700 . A hydraulic fluid supply system  732  supplies hydraulic fluid to all flow paths. Increase flow path  800  includes a stationary increase delivery tube  802  coupled in flow communication with hydraulic fluid supply system  732  and hydraulic fluid transfer assembly  704 . Stationary increase delivery tube  802  delivers hydraulic fluid to a hydraulic fluid transfer assembly increase passage  804  disposed within hydraulic fluid transfer assembly  704 . A rotating increase delivery channel  806  is disposed within actuator cap  720  and receives hydraulic fluid from hydraulic fluid transfer assembly passage  804 . Rotating increase delivery channel  806  directs hydraulic fluid to an increase actuator cap delivery channel  808 . Increase actuator cap delivery channel  808  channels hydraulic fluid circumferentially around actuator cap  720  and is coupled in flow communication with a plurality of increase actuator vane passages  810  which extend forward in axial direction A through actuator vanes  722 . Increase actuator vane passages  810  channels hydraulic fluid to a plurality of increase delivery tubes  812  which deliver hydraulic fluid to increase cavities. 
         [0054]    Hydraulic fluid delivered to increase cavities increases the hydraulic fluid pressure in increase cavities (refer to  FIGS. 6 and 9  as this region of integrated PCM actuator assembly  700  is the same as integrated PCM actuator assembly  300 ). Increased hydraulic fluid pressure in increase cavities increases the hydraulic fluid pressure on one side of pitch actuator vanes  714  which rotates pitch actuator  706  and rotate unison ring  212  (shown in  FIG. 2 ). 
         [0055]    Decrease flow path  900  includes a stationary decrease delivery tube  902  coupled in flow communication with hydraulic fluid supply system  732  and hydraulic fluid transfer assembly  704 . Stationary decrease delivery tube  902  delivers hydraulic fluid to a hydraulic fluid transfer assembly decrease passage  904  disposed within hydraulic fluid transfer assembly  704 . A rotating decrease delivery channel  906  is disposed within actuator cap  720  and receives hydraulic fluid from hydraulic fluid transfer assembly decrease passage  904 . Rotating decrease delivery channel  906  directs hydraulic fluid to mechanical transfer range limiter  716  which directs hydraulic fluid to a decrease range limiter channel  908 . Decrease range limiter channel  908  channels hydraulic fluid to decrease actuator cap delivery channel  910  which channels hydraulic fluid circumferentially around actuator cap  720  and is coupled in flow communication with a plurality of decrease actuator vane passages  912  which extend forward in axial direction A through actuator vanes  722 . Decrease actuator vane passages  912  channels hydraulic fluid to a plurality of decrease delivery tubes  914  which deliver hydraulic fluid to decrease cavities. 
         [0056]    The flow of hydraulic fluid in drain flow path  1000  is bidirectional. Drain flow path  1000  can deliver hydraulic fluid to decrease cavities from hydraulic fluid supply system  516  or can deliver hydraulic fluid to hydraulic fluid supply system  516  from decrease cavities. During normal operations drain flow path  1000  is not pressurized with hydraulic fluid. Drain flow path  1000  includes a stationary drain delivery tube  1002  coupled in flow communication with hydraulic fluid supply system  732  and hydraulic fluid transfer assembly  704 . Stationary drain delivery tube  1002  delivers hydraulic fluid to a hydraulic fluid transfer assembly drain passage  1004  disposed within hydraulic fluid transfer assembly  704 . A rotating drain delivery channel  1006  is disposed within actuator cap  720  and receives hydraulic fluid from hydraulic fluid transfer assembly drain passage  1004 . Rotating drain delivery channel  1006  directs hydraulic fluid to mechanical transfer range limiter  716  which directs hydraulic fluid to a drain range limiter channel  1008 . Drain range limiter channel  1008  channels hydraulic fluid to drain actuator cap delivery channel  1010  which channels hydraulic fluid circumferentially around actuator cap  720  and is coupled in flow communication with a plurality of drain actuator vane passages  1012  which extend forward in axial direction A through actuator vanes  722 . Drain actuator vane passages  1012  channels hydraulic fluid to a plurality of drain delivery tubes  1014  which deliver hydraulic fluid to decrease cavities. 
         [0057]    During normal operations, the hydraulic fluid pressure on both sides of pitch actuator vanes  714  are equal and the volumes of increase cavity and decrease cavity are also equal. Pitch actuator  706  is not rotated and unison rings  212  are not rotated. During decreased pitch operations, the hydraulic fluid pressure in decrease cavity is increased by the introduction of hydraulic fluid to decrease flow path  900 . Increased hydraulic fluid pressure in decrease cavities increases the hydraulic fluid pressure on one side of pitch actuator vanes  714  which rotates pitch actuator  706  and rotate unison ring  212 . Mechanical transfer range limiter  716  operates in the same manner as mechanical transfer limiter  316  and prevents pitch actuator  706  from rotating too far. 
         [0058]    The above-described hydraulic fluid supply systems provide an efficient method for supplying hydraulic fluid to an integrated PCM actuator assembly. Specifically, the above-described hydraulic fluid supply system delivers hydraulic fluid directly to the actuator. When hydraulic fluid is delivered directly to the actuator, less equipment is needed to deliver hydraulic fluid. As such, providing hydraulic fluid directly to the actuator improves the reliability of the integrated PCM actuator assembly. Additionally, integrating the hydraulic fluid supply system within the integrated PCM actuator assembly reduces the weight of the engine. 
         [0059]    Exemplary embodiments of hydraulic fluid supply systems are described above in detail. The hydraulic fluid supply systems, and methods of operating such systems and devices are not limited to the specific embodiments described herein, but rather, components of systems and/or steps of the methods may be utilized independently and separately from other components and/or steps described herein. For example, the methods may also be used in combination with other systems requiring hydraulic fluid, and are not limited to practice with only the systems and methods as described herein. Rather, the exemplary embodiment can be implemented and utilized in connection with many other machinery applications that are currently configured to receive and accept hydraulic fluid supply systems. 
         [0060]    Example methods and apparatus for supplying hydraulic fluid to an integrated PCM actuator assembly are described above in detail. The apparatus illustrated is not limited to the specific embodiments described herein, but rather, components of each may be utilized independently and separately from other components described herein. Each system component can also be used in combination with other system components. 
         [0061]    This written description uses examples to describe the disclosure, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.