TM 1-1520-240-10            6-6-17 d.   Ramp  control  lever  —  DN,  allowing ramp to lower to a position of ground rest,  then  STOP.  If  the  ramp  is  to  be adjusted to a level other than ground rest, or fully closed, with the cargo door in  the  retracted  position,  perform  the following: (1)   Sequence valve plunger — Press and hold. (2)   Sequence  valve  plunger  retainer pin — Rotate to the horizontal posi- tion to lock the plunger in. 2.   Raise the ramp as follows: a.   Sequence valve plunger — Check, re- leased if ramp and cargo door are to be closed. NOTE Perform step b. only if accumulator pressure is used to raise the ramp. b.   EMERG UTIL PRESS valve — Open. c.    Ramp control valve lever — UP, allow- ing ramp to close. If accumulator pres- sure is not sufficient to raise the ramp, operate the hand pump. d.   Ramp control lever — STOP. 6-6-30.   In Flight Operation. CAUTION Do  not  attempt  to  manually  operate  the cargo door when the utility hydraulic sys- tem is pressurized. Motor damage can re- sult. The ramp can be operated up to Vne. At speeds up to 60 knots, the ramp will open normally. At speeds above 60 knots. air pressure from within the cargo compartment is required. To get this pressure, the vent blower can be turned on or the upper section of the cabin door can be opened. 6-6-31.  Ramp Emergency Control. WARNING The  RAMP  EMER  control  switch  is  in- tended  for  emergency  use  only  during smoke and fume elimination procedures. Inadvertent  operation  of  the  cargo ramp and cargo door from the cockpit may re- sult in injury to personnel or damage to equipment. 1.   Open the ramp as follows: a.   RAMP PWR switch — EMERG. NOTE Momentary selection of the RAMP EMERG control switch to the DN position will result in approximately 5 seconds of the ramp and car- go  door  opening  operation  sequence.  The opening sequence of the ramp can be halted during  the  5  second  cycle  by  momentarily placing the RAMP EMER control switch to the UP position. Continuous lowering of the ramp (longer than 5 seconds) can be achieved by holding the RAMP EMER switch in the DN position until the desired ramp position is at- tained b.   RAMP EMERG control switch — DN mo- mentarily then back to HOLD. The ramp downward  cycle  can  be  halted  by  mo- mentarily setting the RAMP EMER con- trol switch to UP. c.    Repeat step b. if necessary, until desired ramp  position  is  achieved,  or  hold  the switch in the DN position until the ramp reaches the desired portion. 2.   Close the ramp as follows: a.   RAMP PWR Switch — EMERG. b.   RAMP EMER control switch — UP until door is closed, then back to HOLD. 6-6-32.  Manual Operation — Cargo Door. CAUTION The ramp must be at or above floor level during takeoffs and landings. CAUTION Do  not  attempt  to  manually  operate  the cargo door when the utility hydraulic sys- tem is pressurized. Motor damage can re- sult. Should the need arise to retract or extend the cargo door section of the ramp manually, insert the handcrank as shown in figure 6-6-11. Crank clockwise to retract. Crank counter clockwise to extend. 6-6-33.  Preparation of General Cargo. Before loading cargo, it is advisable to inspect items of cargo with regard to dimensions, weight, contact pressure, center of gravity, and hazards. This data will be helpful in determin- ing the placement of the load in the helicopter and in com- puting weight and balance. Refer to TM 10-450-2. 6-6-34.  Cargo Dimensions. Any item of cargo which appears to have critical dimensions for  loading  into  the  helicopter  should  be  measured  and checked against door and compartment dimension limita- tions.