SYSTEM OPERATION Before flight, the ejection seat safe/arm handle is kept in the SAFE position. In this position, the visible portion of the handle is colored white and placarded as SAFE. When the aircraft is ready for flight, the pilot sets the safe and arm handle to the ARMED position. In this position, the visible portion of the handle is colored with yellow and black markings and placarded as ARMED. The ejection sequence (fig. 6-19) starts when the pilot pulls the ejection control handle. The up- ward movement of the handle removes two sears from the seat initiator and fires two cartridges with the seat initiator. Firing Sequence Ballistic gas generated by the right cartridge within the seat initiator actuates the pin puller. The gas also activates the shielded mild detonating cord (SMDC) initiator. The SMDC then activates the aircraft identification friend or foe unit (IFF) and the canopy jettison system. Additionally, it activates the inertia reel cartridge and the 0.3-second delay initiator. Ballistic gas generated by the left cartridge within the seat initiator starts the 0.3-second delay initiator. Ballistic gas pressure from either 0.3-second delay initiators ignites the primary cartridge within the catapult. Catapult Firing and Initial Seat Movement Ballistic gas pressure developed by the cat- apult primary cartridge causes the inner and intermediate barrels within the catapult to rise and release the top latch mechanism. The secondary cartridges within the catapult fire progressively as the rising barrels are exposed to the heat and pressure of the primary cartridge gas. Progressive firing of the catapult secondary cartridges provides a relatively even gas pressure during catapult extension. This eliminates excessive g-forces during ejection. As the seat moves upward, the emergency oxygen system is activated. A trip rod withdraws the firing link from the drogue gun and starts a 0.5-second internal timer. Another trip rod withdraws the firing link from the time-release mechanism. Aircraft electrical power and personal services (oxygen and communication) between the seat and the aircraft are disconnected. At this point in the sequence, the leg restraint lines are drawn through the snubbing units to restrain the pilot’s legs to the seat bucket. When the leg restraint lines become taut, the upper portion of the leg restraint line shears from the lower portion, which is attached to the floor bracket. Forward movement of the lines is prevented by the snubbing units. After 72 inches of catapult extension, the rocket motor initiator is fired by a cable that is attached to the drogue gun trip rod. Ballistic gas pressure generated by the cartridge within the rocket motor initiator is routed to a pressure actuated firing mechanism located on the rocket motor. Flame and pressure ignite the rocket motor propellant grain. The thrust of the motor is approximately 4,500 pounds and lasts for 0.25 second. Aircraft and Seat Separation Separation of the seat from the aircraft occurs at approximately 76 inches of catapult extension. At this point, the inner barrel separates from the intermediate barrel. The seat is now clear of the aircraft. The drogue gun primary cartridge fires after a 0.5-second delay to propel the piston from the drogue gun barrel. The inertia of the piston extracts the parachute flap closure pin and deploys the 22-inch controller drogue. The controller drogue, in turn, deploys the 60-inch stabilization and retardation drogue. The 0.5-second time delay allows the seat to reach its maximum altitude before the drogues are fully developed. The seat will stabilize and decelerate because of the drogues, which are held to the seat by the scissor mechanism. If the drogue gun primary cartridge fails to fire, ballistic gas pressure will pass to the drogue gun when the time-release mechanism (TRM) fires. This gas shears the firing pin retaining pin. The firing pin then strikes the secondary drogue gun cartridge, which results in drogue deploy- ment. Should both the drogue gun primary and time-release mechanism cartridges fail to fire, operation of the manual override handle will fire 6-26