the  manual  override  initiator  cartridge.  This duplicates the function of the TRM and fires the drogue  gun  secondary  cartridge.  The  drogue gun  then  deploys  the  drogue  parachutes  and personnel parachute concurrently. The  TRM  altitude-sensing  barostatic  time release   prevents   the   1.5-second   timer   from starting  at  altitudes  above  11,500  feet.  The barostatic  time  release  ensures  that  the  pilot descends rapidly through the upper atmosphere to  a  more  survivable  altitude.  At  altitudes between 7,500 and 11,500 feet, the time delay for deployment of the personnel parachute is con- trolled  by  an  internal  g-limiter,  which  interrupts the timing sequence until the deceleration force is less than 1.5 g’s. This results in lower parachute opening loads. At altitudes below 7,500 feet, the 1.5-second timer starts without interruption. After the 1.5-second timer delay, the TRM cartridge fires. This releases the upper restraint mechanism,  lower  restraint  mechanism,  parachute mechanical  lock,  and  drogue  shackle.  When  the drogue  is  free  from  the  scissor  mechanism,  it deploys the personnel parachute. The personnel parachute lifts the pilot and the survival kit from the seat and pulls the sticker-clip strap lugs from their clips. This is necessary to ensure that collision between the seat and the pilot is avoided. The radio  beacon  activates  when  pilot  and  seat separation  occurs.  Then  a  normal  parachute descent  begins. While descending in the parachute, the pilot can pull the survival kit handle to separate the kit halves. This allows deployment and automatic inflation of the life raft. The life raft and survival kit  items  are  connected  by  a  lanyard  to  the survival kit lid, which is attached to the pilot. SYSTEM  COMPONENTS The SJU-5/A ejection seat system (fig. 6-20) provides support for the pilot during normal flight conditions and a method of escape from the air- craft  during  emergency  conditions.  Selected  seat system  components  are  discussed  in  the  follow- ing paragraphs and keyed to figure 6-20. Catapult The catapult (3) is a cartridge-actuated device that provides the initial force required to eject the 6-28 seat  from  the  aircraft.  The  catapult  is  located within the main beam assembly (6) and is attached to the bulkhead of the cockpit by two mounting lugs. The ejection seat is installed on the catapult with   three   pairs   of   slippers   located   on   the inboard  side  of  the  main  beam  assembly.  The main  beam  assembly  fits  into  catapult  guide rails  located  on  the  outboard  sides  of  the catapult’s  outer  barrel.  The  ejection  seat  is locked to the catapult by the top latch mechanism. The catapult consists of three major parts: the inner barrel, the intermediate barrel, and the outer barrel. INNER BARREL.— A neck-shaped piston head,  fitted  with  a  set  of  expander  and  piston rings, is attached to the lower end of the inner barrel to provide a gas seal with the intermediate barrel. A breech is located at the upper end of the inner barrel for the primary firing mechanism and cartridge. The breech has a groove on the out- side edge into which the plunger of the top latch mechanism of the ejection seat is engaged. INTERMEDIATE BARREL.— The inter- mediate  barrel  is  located  between  the  inner barrel  and  the  outer  barrel.  The  intermediate barrel  increases  the  length  of  catapult  extension. It also restrains bending loads incurred during ejection. A piston head fitted with two sets of six expander and piston rings is attached to the lower end. The piston head serves as a gas seal between the intermediate barrel and the outer barrel. A guide bushing is riveted to the upper end of the intermediate barrel to keep the inner barrel steady during extension. The guide bushing rivets are sheared by the neck-shaped piston head of the inner  barrel  during  ejection.  This  allows  separa- tion of the inner and intermediate barrels. Twelve pressure rings are installed on the intermediate barrel to absorb the inertia forces encountered during barrel separation. OUTER BARREL.—  The outer barrel houses the  intermediate  and  inner  barrel  assemblies.  Two breeches are located on the aft side to accept the auxiliary cartridges. Two guide rails are bolted on the outboard sides of the outer barrel. The lower end is used to attach the catapult to the aircraft. The upper end has a square aperture to engage the  plunger  of  the  top  latch  mechanism.  The upper fitting is threaded for the guide bushing that retains  the  intermediate  barrel.  The  guide  bushing is locked in place by a dowel screw.