0.9 inch (approximately), the shoulder on the lock
strikes the immobilized unlock sleeve and stops.
This action releases the upper tangs of the lock
and unseals the rocket motor nozzle by severing
the nozzle plug and retaining the motor lock disk.
The hot, pressurized gases from the cartridge
then pass into the rocket motor assembly through
the nozzle. These gases energize the rocket motor
firing mechanism, which ignites the rocket igni-
tion material. The rocket ignition material and/or
the hot gases from the booster cartridge ignite the
rocket motor solid-propellant grain. The rocket
motor then provides additional thrust to the air-
crewman seat after separation of the booster and
The rocket motor internal pressure energizes
two output cartridge firing mechanisms that fire
the output cartridge. The output cartridge then
actuates other escape devices, which are attached
to the output fitting.
INSPECTION OF THE ROCKET CAT-
APULT. The rocket catapult must be inspected
whenever it is removed from the shipping
container for use and prior to returning it to
stowage. If the rocket catapult is found in a
hazardous condition, explosive ordinance disposal
(EOD) personnel must be immediately notified.
After the rocket catapult is rendered safe, or if
it is rejected for any other reason, it must be
disposed of in accordance with NAVAIR 11-85-1.
Inspect the rocket catapult for damage, such
as dents and corrosion; reject the unit if it has any
visible defects. Inspect the head end cap for
tightness by grasping the cross-shaped head end
trunnion (word AFT stamped on face) with one
hand and attempt to tighten the head end cap with
the other. If any cap motion is detected, do not
reject the unit but repair it in the following
Back off head end cap until the U-shaped slot
in the rocket motor tube is exposed. Inspect to
see if the head end trunnion pin is completely
contained within the U-shaped slot. If the entire
pin is not visible within the slot, reject the unit.
NOTE: Pin is not necessarily bottomed in the
If unit passes inspection, apply Locktite
(grade N) to exposed thread area, hand tighten
cap, and then tighten with strap wrench. Inspect
the adjustment ring for tightness by grasping the
cross-shaped head end trunnion (word AFT
stamped on face) with one hand and attempt to
tighten the adjustment ring with the other. If more
than a few degrees of side-to-side play is evident
in adjustment rings with six holes (two con-
figurations of adjustment rings are in service
one with six holes and one without holes), reject
the unit. If the adjustment ring without holes is
found to be loose, do not reject the unit but repair
it in the following manner.
Back off the adjustment ring until it contacts
the head end cap, and apply Locktite sealant
(grade N) to the exposed, degreased thread area.
Ensure that the front body housing is tightened
down against the catapult tube prior to hand
tightening the adjustment ring against the front
body housing. Allow Loctite sealant to set.
Reinspect prior to use.
Learning Objective: Recognize the com-
ponents, seat system/subsystems, support
components, system operations, compo-
nent test and test equipment, and corrosion
control procedures for the Martin-Baker
SJU-5/A ejection seat.
The SJU-5/A ejection seat is a ballistic
catapult and rocket system that gives the pilot a
quick and safe means of escape from an aircraft.
The seat system includes an initiation system that
jettisons the canopy, positions the pilot for
ejection, and fires the seat catapult. Canopy
breakers on the top of the seat allow the seat
capability to eject through the canopy should it
fail to jettison.
As the seat ejects from the aircraft, a rocket
motor on the bottom of the seat is fired. Then
a drogue gun is fired to deploy two drogue
parachutes. These parachutes either remain
attached to the top of the seat or they are released
to deploy the main parachute, depending upon
the altitude and the number of gs applied to the
seat. An automatic time-release mechanism opens
the main parachute container and releases the
drogue parachutes that deploy the main