Abstract:
A mobile worker platform providing access to the rotor area of a helicopter having outriggers spaced to straddle the helicopter landing gear.

Description:
TECHNICAL FIELD 
     This invention relates to a rolling worker access platform facilitating servicing and repair of helicopters. 
     BACKGROUND OF THE INVENTION 
     The servicing and repair of helicopters requires a movable structure by which a servicing or repair person can obtain access to the part of the helicopter requiring service. The rotor for instance is one such area requiring inspection, servicing and repair. Stepladders could be used, however, they do not provide safe support nor do they permit sufficient lateral movement of the worker. The support structure for permitting a worker to service or repair a helicopter needs to be selectively mobile so that it can be manually moved into a rotor servicing position at either lateral side of the helicopter. 
     BRIEF DESCRIPTION OF THE INVENTION 
     A mobile worker access platform for servicing helicopter is provided which is light weight and easily positioned manually to service the helicopter. The support tower for a worker platform or floor is laterally narrower than the floor thereby providing an overhanging floor at both lateral sides of the platform. A pair of wheeled outriggers supporting the tower are spaced from one another far enough to straddle the landing gear or runners and extend beneath the fuselage of the helicopter. The tower structure between the outriggers is high enough to clear the runner supports. This construction permits the worker platform to be moved close to the helicopter with the floor extending over a side of the fuselage thereby placing the servicing person close to the rotor area. A convenient inclined stairway serves as part of the support tower for the floor of the platform and has a front outrigger secured thereto. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     One embodiment of the invention is illustrated in the drawings, in which: 
     FIG. 1 is a side view of a helicopter access platform and includes an outline of a helicopter with parts of the rotor and tail boom assembly broken away; 
     FIG. 2 is a top view of the helicopter access platform; 
     FIG. 3 is a front view of the helicopter access platform; 
     FIG. 4 is rear end view of the helicopter access platform positioned at the left side of the helicopter; 
     FIG. 5 is a rear view of the helicopter access platform positioned at the right side of the helicopter; 
     FIG. 6 is a section taken on the line VI—VI in FIG. 5; 
     FIG. 7 is a partial rear view of an outrigger; 
     FIG. 8 is a partial top view of an outrigger; and 
     FIG. 9 is a section taken along the line IX—IX in FIG.  2 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIGS. 1 and 4, a helicopter access platform  11  is shown in a servicing position on the left hand side of a helicopter  12  which has a rotor  13  on a vertical rotor shaft  14  and a fuselage  16  supported on a pair of parallel laterally spaced ground engageable runners  17 ,  18 . The fuselage  16  is low to the ground and may have as little as 3 decimeters of clearance. In order to service the rotor area of the helicopter  12  the platform  11  is provided with an elevated quadrilateral floor  19  supported on a support tower  21  which includes four vertical support columns  22 ,  23 ,  24 ,  26  having upper ends secured in supporting relation to the floor  19 . The lower ends of the columns  22 ,  23  are secured as by welding to a fore and aft extending horizontal beam  31  and the lower ends of columns  24 ,  26  are secured as by welding to a fore and aft extending horizontal beam  32  which is parallel to beam  31 . Cross braces  36 ,  37  having upper ends welded to the left side of the floor  19 , as viewed in FIG. 3, and have lower ends welded to the beam  31 . Similarly positioned cross braces, not shown, are welded to the right side of the floor  19  and the beam  32 . As viewed in FIGS. 4 and 5 cross braces  38 ,  39  have their upper ends welded to the floor and their lower ends welded to a cross brace  41 , the opposite ends of which are welded to the beams  31 ,  32 . As shown in FIGS. 3,  4  and  5  the floor  19  extends laterally beyond the support columns  22 ,  23 ,  24 ,  26 . 
     As shown in FIGS. 1,  2  and  3  the support tower  21  includes an inclined stairway  43  formed by a pair of parallel stair joints  44 ,  46  and a plurality of steps  47 , the opposite ends of which are welded to the joists  44 ,  46 . The upper ends of the stair joists  44 ,  46  are welded respectively, to the upper ends of the columns  22 ,  24  and to the front side of the floor  19 . The joists  44 ,  46  have the same lateral spacing as the columns  22 ,  24 , the columns  23 ,  26  and the support beams  31 ,  32 . Thus the joist  44 , the beam  31  and the columns  22 ,  23  are coplanar. Likewise the joist  43 , the beam  32  and the columns  24 ,  26  are coplanar. The front ends of the support beams  31 ,  32  terminate at an angle which corresponds to the incline of the stairway joists  44 ,  46  thereby facilitating welding the front ends of the beams  31 ,  32  to the underside of the joists  44 ,  46 . 
     As illustrated in FIGS. 1,  2 ,  3 ,  4  and  5 , a guard railing is provided for the floor  19  which includes posts  51 ,  52 ,  53 ,  54   56  and rails  61 ,  62 ,  63 ,  64 ,  65 ,  66 ,  67 ,  68 ,  69 . A gateway opening is provided between railing posts  52 ,  53  and a similar gateway opening is provided on the right hand side of the access platform  11 , as viewed in FIG.  4 . Toe guard panels the height of oxford shoes provided around the perimeter of the floor  19  except for the stairway opening between the railing posts  57 ,  58 . A toe guard panel  71  has its opposite ends welded to railing posts  51 ,  52 . A toe guard panel  72  has its opposite ends welded to railing posts  53 , 54 . A toe guard panel  73  has its opposite ends welded to railing posts  56 ,  57  and a toe guard panel  74  has its opposite ends welded to rail posts  58 ,  51 . In a like manner a toe guard panel, not shown is provided between the railing post  56  and a post at the front side of the gateway on the right hand side of the access platform. A pair of gates  76 ,  77 , similar in construction, are provided for the left and right gateways in the safety railing. The gate  76  is pivotally connected to the railing post  53  on a vertical pivot axis  78  and the gate  77  is pivotally connected to the railing post  54  on a vertical axis  79 . Both gates  76 ,  77  open only in a laterally inward direction. Broken lines  81  in FIG. 2 show gate  76  in a slightly open position and broken lines  82  show gate  77  in a slightly open position. Each of the gates  76 ,  77  can be separately opened  90  degrees to where it is parallel to guard rail  63  at the rear of the floor  19 . The gates  76 ,  77  may be opened when the access platform is placed for servicing the helicopter  12  thereby giving the servicing person better access to the areas requiring service. Or the servicing person may step out onto the fuselage  16  if necessary. Tabs  83 ,  84  are provided on the gates to prevent them from being opened laterally outwardly. Each of the gates is provided with a toe guard panel. As shown in FIG. 1 a toe guard panel  86  is secured to the lower ends of vertical connectors  87 ,  88  which have their upper ends welded to a U-shaped component  89  of the gate  76 . 
     The access platform  11  is supported at its front and rear by a pair of low to the ground wheeled outriggers  91 ,  92 . The rear outrigger  92  is rigidly connected to the beams  31 ,  32  by studs  93 ,  94  and the front outrigger  91  is rigidly connected to the second step  47 , from the bottom of the stairway, by short studs  96 ,  97 , as shown in FIGS. 3 and 9. 
     As shown in FIGS. 1,  2 ,  3 ,  4 ,  5 ,  6 ,  7 , and  8  the rear outrigger  92  includes a T-shaped transverse horizontal truss  101  formed by welding a hollow upper tube  102  of rectangular section to a rectangular section hollow lower tube  103  as illustrated FIGS. 6 and 7. The tube  102  is approximately twice as wide as it is high and the tube  103  is approximately three times as high as it is wide. As shown in FIGS. 7 and 8, a channel member  106  has a vertical flange welded to the lateral end of the tube  103  and has a horizontal flange to which a wheeled swivel caster  107  is secured by releaseable fasteners in the form of four threaded studs  108  and nuts  109 . A small vertical plate  11  is welded to the tubes  102 ,  103  and the channel member  106  and a gusset  112  is welded to the plate  111  and to the horizontal flange of the channel member  106 . A wheeled swivel caster  113  is mounted on a channel member  114  at the other end of the T-shaped section of the outrigger  101  in a reverse image manner. The wheels of the casters  107 ,  113  make contact with a support surface  117  at points approximately vertically beneath the laterally opposite edges of the floor  19 . 
     As shown in FIGS. 3 and 9, the outrigger  91  at the front of the access platform is similar in construction to the rear outrigger  92  and has a T section truss  121  to which a pair of channel members  122 ,  123  are welded. A pair of wheeled swivel casters  126 ,  127  are mounted on the channel members  112 ,  123  and positioned vertically below the lateral edges of the floor  119 . The swivel casters  126 ,  127  have manually lockage wheels to prevent movement of the access platform  11  when in a helicopter servicing position as shown in FIGS. 1,  4  and  5 . The wheels of the swivel casters  107 ,  113  may also be selectively lockable. 
     The front to rear spacing of the outriggers  91 ,  92  is greater than the length of the runners  17 ,  18  so as to permit them to straddle the runner at either side of the helicopter thereby permitting the floor  19  of the access platform to be positioned close to the helicopter. The support beams  31 ,  32  are at a sufficient elevation to define an underside opening high enough to clear the runner or undercarriage support members  128 ,  129 . As shown in FIGS. 4 and 5 the floor  19  extends laterally beyond the support tower  21  at a height above the fuselage  16  of the helicopter. The overhang of the floor  19  permits the service personnel close access to the rotor area which requires critical, accurate inspection and servicing. As shown in FIGS. 4 and 5 the outriggers  91 ,  92  extend laterally beneath the fuselage  16  to the same extent as the floor  19  extends laterally over the fuselage  16 . 
     As illustrated in FIGS. 1,  2 ,  3 ,  4 , and  5 , bumper pads  131 ,  132  of resilient cushioning material are secured to the laterally opposite sides of the floor  19  and similar pads  113 ,  134 ,  136 ,  137  are secured to the columns  22 ,  23 ,  24 ,  26 . The pads are designed and provided to prevent damage to the fuselage of the helicopter. 
     Practical Application 
     Helicopters require careful diligent servicing to insure efficient, safe operation. Servicing the rotor area of the helicopter is critical to functional operation of the helicopter. The herein disclosed access platform provides a stable floor positioned over the fuselage and close to the rotor area. The access platform is symmetrical, permitting it to be placed at either side of the helicopter. The support tower  21  for the floor  19  includes four columns  22 ,  23 ,  24  and  26  mounted on a pair of parallel longitudinally extending beams  31 ,  32  which have their front ends connected to an inclined stairway  43  whose upper end is secured to the floor  19 . Thus the stairway serves as a fore and aft structural brace in the floor support tower  21 . By aligning the columns  22 ,  23 , the beam  31 , the stringer  44  and the stud  93  in a coplanar manner and by aligning the posts  24 ,  26 , the stringer  43 , the beam  32  and the stud  93  in a coplanar manner, efficient use of materials is achieved thereby reducing weight and cost while maximizing rigidity and strength. The stairway provides a convenient support for the front outrigger  91  with a minimum amount of connecting framework. The columns, the beams, the studs, the T section members of the outrigger and the stairway are made of aluminum tubes which provide strength and low weight. The wheeled access platform is sufficiently light to permit it to be moved into and out of a servicing position by one or two servicing personnel. Its light weight enhances its air transportability which is important when the helicopters are moved to new bases of operation. The toe guard panels around the floor and the inward only swinging gates contribute to the safety of the helicopter servicing activity.