Ejection Seat Initiator
With the safe and arm handle in the down or
ARMED position, an upward pull on the
ejection control handle removes the two sears
from the firing mechanisms and causes the two
cartridges within the initiator to fire. Gas pressure
from either cartridge will initiate seat ejection.
Manual Override Initiator
Aft rotation of the manual override handle
positions the safe and arm handle up to the SAFE
position and releases the lower restraint. In this
position, the pin puller engages a slot in the
manual override handle linkage and prevents
actuation of the manual override initiator.
During the ejection sequence, the pin puller is
retracted inboard. This allows the manual over-
ride initiator to be actuated and override the
automatic sequencing. Gas pressure from the
manual override initiator is piped to the time-
release mechanism and the secondary cartridge in
the drogue gun.
During the ejection sequence, gas pressure
from the right seat initiator cartridge enters the
pin puller and operates a spring-loaded ball lock.
This allows the- pressure to retract the pin and
disengage it from the manual override linkage.
Seat Survival Kit
The seat survival kit is opened by operating
the release handle located on the right forward
side of the kit. During the ejection sequence, the
oxygen hose and communication lead disconnect
from the aircraft. The emergency oxygen and
radio beacon are automatically actuated. During
parachute descent, the pilot may operate the
release handle to open the survival kit. This allows
deployment and inflation of the life raft. The life
raft and survival equipment are connected by a
lanyard to the survival kit lid, which is attached
to the pilot.
Manual Override System
Operation of the manual override handle will
rotate the cross shaft of the lower harness locks,
leg restraint line locks, and the negative-g strap
lock. This is necessary for emergency ground
egress from the aircraft. Full aft rotation of the
handle is prevented by engagement of the pin
puller piston in a slot of the manual override
handle linkage. This prevents firing of the manual
During the ejection sequence, gas pressure
from the right seat initiator cartridge operates the
pin puller to withdraw the pin puller piston from
the slot in the manual override handle linkage.
In the event of a time-release mechanism failure
or drogue gun failure above barostatic altitude,
aft rotation of the manual override handle will
fire the manual override initiator. Gas pressure
from the manual override initiator cartridge
operates the lower harness release system. It will
also pass up the trombone fitting and fire the time-
release mechanism cartridge. This cartridge
operates the upper harness release mechanism,
scissor mechanism release plunger, and parachute
lock. Additionally, the gas pressure passes to the
drogue gun and fires the secondary cartridge.
Leg Restraint System
As the seat travels up the guide rails during
the ejection sequence, the leg restraint lines are
drawn through the snubbing units. This action
pulls the pilots legs aft against the seat bucket.
As the seat continues to rise, the leg restraint lines
become taut. When the force on the bottom
fittings reaches approximately 900 pounds, the
shear ring will shear. The shearing releases the
lower portion of the leg restraint lines.
Automatic Harness Release System
Firing of the time-release mechanism cartridge
moves the piston and connecting rod down and
rotates the cross shaft. Rotation of the cross shaft
releases the inertia reel locking plungers and
releases the inertia reel straps. Simultaneously, gas
pressure is routed down the trombone fitting to
fire the cartridge in the manual override initiator.
Gas pressure from the manual override initiator
cartridge presses against the head of the piston.
Movement of the piston rotates the bell crank
lever and releases the spring-loaded locking
plungers of the lower harness locks. This releases
the lap belt lugs and rotates the cross shaft.
Rotation of the cross shaft releases the looking
plungers in the leg restraint line and negative-g
COMPONENT TEST AND
Ejection seats and associated components are
carefully designated, manufactured, and tested to
ensure dependable operation. Such equipment
must function perfectly the first time it is used.
Malfunction or failure to operate usually results
in severe injury or death to crew members. You