TM 1-1520-240-10            6-6-1 SECTION  VI.  CARGO LOADING 6-6-1.  General. This  section  contains  information  and  instructions  for loading and securing cargo in the helicopter. t lists and describes the items of equipment incidental to these op- erations, instructions for their use, and illustrations where necessary or desirable. It is not the intent of this section to teach principles of cargo loading. It is the purpose of this section to provide detailed information on cargo load- ing with regard to this helicopter. 6-6-2.  Cargo Compartment. The cargo compartment (fig. 6-6-1) is 366 inches long, 90 inches wide, and 78 inches high. These dimensions are uniform through out the cargo compartment, unless the aircraft is configured with HICHS (fig. 6-6-1). The lower rescue door is opened for rescue operations, aerial load- ing, and external cargo transport operations. A hydrauli- cally operated door and ramp provide a means for quick and efficient straight-in loading and unloading. NOTE Figure 6-6-2 shows the maximum cube size which can be taken into the helicopter through either the main cabin entrance, utility hatch, or cargo loading ramp. 6-6-3.  Main Cabin Entrance. The main entrance door is located on the right side of the cargo compartment at the forward end and measures 66 inches in height by 36 inches in width. The door is com- posed of two sections: the upper section rolls inward and upward to a rest position overhead; the lower section opens outward and downward and serves as a step in the lowered position. 6-6-4.  Utility Hatch Door. The  utility  hatch  door  is  in  the  center  of  the  cargo compartment floor between stations 320 and 360. the door is hinged along its entire forward edge. It opens upward and forward to expose the lower rescue door and the cargo hook. The door is unlatched by pressing the knob labeled PUSH, and is latched by pressing the un- marked knob. NOTE When  opening  or  closing  the  lower  rescue door, be certain that the cargo hook is proper- ly  stowed  and  supported  by  the  restraining straps. In addition, close the rescue door, us- ing the actuator only to the point where the latch can engage; the latches will then lift the door and compress the door seal. 6-6-5.  Lower Rescue Door. When closed, the lower rescue door forms a part of the fuselage bottom. It is accessible through the utility hatch door. The lower rescue door is secured by four latches centered around the door perimeter. These latches are connected by linkage to an actuator labeled OPEN and CLOSED. A handcrank, stowed in spring metal clips on the left side of the fuselage, is used to unlatch the door and turn the gears. A drive shaft, which is turned by the gears, moves the door actuator links. The door opens downward and aft underneath the fuselage where it re- mains during operation. CAUTION Although tightening of the tiedown straps may be necessary to reduce internal load vibrations,   excessive   tightening   of   tie- downs attached to the outboard row of tie- down fittings will limit the effectiveness of the isolated cargo floor. 6-6-6.  Cargo Compartment Floor. The floor is made of extruded panels, riveted together in sections.  Raised  extruded  ridges,  running  the  entire length of the floor, provided surfaces on which cargo is moved. The flooring in the cargo compartment contains sections  on  either  side  of  the  centerline  which  are strengthened to serve as vehicle treadways. The flooring from station 200 to 400 and from buttline 44 left to 44 right,  rests  on  rubber  vibration  isolators  which  reduce overall  internal  load  vibrations.  Tiedown  fittings  (fig. 6-6-3) for securing cargo are installed in the floor. There are also studs for attaching troop seats, litter supports, and the base plate for the maintenance crane. The floor- ing is covered with a walkway compound which provides a  non-skid  surface  for  personnel  and  for  vehicles.  In construction, the ramp floor is identical with the cargo floor. NOTE Whenever  possible,  place  all  wheeled  ve- hicles entirely on the treadways between sta- tions 200 and 400. 6-6-7.  Strength Areas. The  weight  which  the  cargo  compartment  floor  (fig. 6-6-4) can support varies. These variations are largely due to difference in strength of supporting frames and fuselage   construction,   not   because   of   varying   floor strength. To gain the maximum benefit from the cargo compartment floor, the following definitions and weight limitations must be observed.