Harness Release and Seat Separation

The harness release system provides automatic release of the shoulder harness and lap belts during the ejection sequence. The survival kit and shoulder harness are locked in the seat by three retaining pins, two through the survival kit lugs and one through the shoulder harness inertia reel strap lugs. Automatic release from the seat during the ejection sequence is accomplished by the harness release actuator, using a pressure-actuated 0.3-second delay initiator. Gas pressure, which exits from the outlet port of the harness release actuator, is used to actuate the man/seat separator rocket in the seat separation subsystem.

PRESSURE-ACTUATED 0.3-SECOND DELAY INITIATOR.- The 0.3-second initiator is located on the rear right side of the seat above the harness release actuator. The 0.3-second initiator is a pressure-actuated device with a conventional firing piston secured in the cocked position by a shear pin. Gas pressure from the rocket catapult actuates the initiator, which fires into the inlet port of the harness release actuator.

HARNESS RELEASE ACTUATOR.- The actuator is mounted on the rear right side of the seat. The actuator contains a piston and rod that are actuated by a 0.3-second delay initiator firing into the inlet port. Gas pressure exits from the outlet port to actuate the man/seat separator rocket. The piston rod, which extends below the actuator, is connected to the harness release bell crank. The bell crank initiates simultaneous automatic actuation of each component of the harness release system to cause man/seat separa-tion during seat ejection. If the lap belts and shoulder harness assemblies fail to release automatically, the crew member can actuate the harness release handle to release the assemblies. The handle is also useful for routine removal and installation of the parachute and survival kit. The following components are connected to the multiple arm bell crank: harness release actuator piston rod, survival kit retaining pins, inertia reel straps retaining pin cable, harness release handle cable, and bell crank return spring. The actuator also actuates the firing control disconnect actuating arm.

MAN/SEAT SEPARATOR ROCKET.- The separator rocket is mounted on the aft inboard side of the headrest area of each seat. The separator rocket is used to separate the crew member from the seat and drive the seat into a divergent trajectory. Pressure from the harness release actuator outlet port is used to initiate the separator rocket. The separator rocket nozzle is oriented to direct the exhaust plume forward, up, and away from the crew member.