TM 55-1510-222-10 pressure    vessel    while    in    flight.        The    door    locking mechanism is operated only from inside the aircraft, and is  operated  by  two  handles,  one  in  the  bottom  forward portion of the door and the other in the upper aft portion of the door.  When the upper aft handle is operated per placard  instructions,  two  rotating  cam-type  latches  on the  forward  side  of  the  door  and  two  on  the  aft  side, rotate, capturing posts mounted on the fuselage side of the  door  opening.  The  bottom  handle,  when  operated per  placard  instructions,  actuates  four  pin  lug  latches across the bottom of the door.  A button on the upper aft handle   must   be   pressed   before   the   handle   can   be released to open or latch the door.  A latching lever on the  bottom  handle  must  be  lifted  to  release  the  handle before the lower latches can be opened.  These act as additional    aids    in    preventing    accidental    opening    or unlatching of the door.  The cabin and cargo doors are equipped  with  dual  sensing  circuits  to  provide  the  crew with remote indication of cabin/cargo door security.  An annunciator  placarded  CABIN  DOOR  will  illuminate  if the cabin or cargo door is open and the battery switch is on.      If   the   battery   switch   is   off,   the   annunciator   will illuminate  only  if  the  cabin  door  is  not  securely  closed and   latched.      The   cabin/cargo   door   sensing   circuit receives power from the hot battery bus. CAUTION When operating the cargo door, ensure  that  the  cabin  door  is  closed and  locked.  Operating  the  cargo  door while   the   cabin   door   is   open   may damage  the  door  hinge  and  adjacent structure. (1) Opening the cargo door. CAUTION Avoid  side  loading  of  the  gas  springs to prevent damage to the mechanism. 1. Handle access door (lower forward corner of door) Unfasten and open. 2. Handle  Lift  hook  and  move  to OPEN position. 3. Handle access door Secure. 4. Handle  access  door  (upper  aft corner of door) Unfasten and open. 5. Handle  Press  button  and  lift  to OPEN position then latch in place. 6. Handle access door Secure. 7. Door   support   rod   Attach   one end to cargo door ball stud (on forward side of door). 8. Support rod detent pin Check in place. 9. Cabin door sill step Push out on and  allow  cargo  door  to  swing open. Gas springs will automatically open the door. 10. Door   support   rod   Attach   free end to ball stud on forward fuselage door frame. (2) Closing the cargo door. CAUTION Avoid  side  loading  of  the  gas  springs to prevent damage to the mechanism. 1. Door  support  rod  Detach  from- fuselage door frame ball stud, then firmly grasp free end of  rod  while  exerting  downward  force  to  overcome  the pressure of gas spring assemblies, then remove support rod  from  door  as  gas  spring  assemblies  pass  the  over- center position. 2. Cargo   door   Pull   closed,   using finger hold cavity in fixed cabin door step. 3. Handle  access  door  (upper  aft corner of door) Unfasten and open. 4. Handle   Press   button   and   pull handle down until it latches in closed position. 5. Handle access door Secure. 6. Handle access door (lower forward corner of door) Unfasten and open. 7. Handle    Move    to    full    forward position. 8. Safety   hook   Check   locked   in position by pulling aft on handle. 9. Handle access door Secure. c. Cabin    Door    Annunciator.        As    a    safety precaution, two illuminated MASTER CAUTION annunciators     in     the     glare     shield     and     a     steadily illuminated CABIN DOOR amber caution annunciator in the 2-17