La variabilidad y dispersión en el muestreo

The seat bucket is constructed to form a square pan and houses the seat operating controls. The extended back, the bottom and front are made from sheet aluminum alloy. The sides are solid aluminum alloy plates and extend forward to provide thigh protection and support. The bucket is secured to studs incorporated into sliding runners on the seat main

beams by four nuts. Interference devices on the rear of the seat bucket and on the main beam assemblies ensure that only the correct seat bucket is installed in forward and aft cockpits (fig. 2-18).

Because of aircraft installation requirements, SJU-17(V)1/A, 2/A and 9/A seat bucket assemblies are one inch wider than SJU-17(V)3/A thru 6A assemblies.

Detail assemblies are essentially similar between aft seat buckets.

The back of the seat bucket contains a rigid molded pad that forms the backrest. It is contoured so at ejection the seat occupant is automatically pulled back by the shoulder harness reel into the correct ejection posture. The backrest is secured by a screw through each side of the seat bucket. A cushion attached to the backrest provides additional comfort.

Underseat Rocket Motor MK 123 MOD 0

An underseat rocket motor MK123 MOD 0 (forward seat) or MK 124 MOD 0 (aft seat) installed under the seat bucket is secured to the side plates by nuts and bolts. Differences in mounting bolt sizes

2-17

Figure 2-18.—Interference devices, seat bucket to main beams for the forward and aft seats (SJU-17(V)2/A).

2-18

Figure 2-19.—Underseat rocket motor mounting bolt sizes (SJU-17(V)2/A).

Figure 2-20.—Lower harness release mechanism (SJU-17(V)1/A, 2/A and 9/A).

(fig. 2-19) ensure that the correct rocket motor is installed. A gas pipe to the rocket motor firing mechanism is connected to a trombone tube on the LH rear of the seat bucket. The trombone tubes on the rear of the seat bucket connect to ballistic manifolds mounted on the main beams. Connections are a push fit secured by key operated quick-release pins, gas integrity being maintained by O-ring seals.

Leg Restraint System

The lower harness locks and release mechanism are within the lower rear corners of the seat bucket (fig. 2-20). Halfway up the inner face of the seat bucket sides are sticker clips. The pin puller is mounted at the rear of the seat bucket on the lower right hand side.

Two leg restraint line snubbers, each with a leg restraint line, are attached to the front face of the seat bucket. Pulling inboard on the fabric loops attached to the release plungers on the inboard side of each snubber will release them to adjust the leg lines. The leg restraint lines taper plugs are secured in locks positioned on the seat bucket side plates.

Seat Height Actuator

The seat height actuator (fig. 2-21) adjusts the seat bucket vertically in relation to the seat beams. The assembly consists of a vertical electric motor and housing assembly connected by a transverse gearbox assembly to the upper end of a screwjack housing.

2-19

Figure 2-21.—Seat height actuator (SJU-17(V)3/A and 4/A).

Operating Controls

The ejection control handle (figs. 22 and 23) is on the front of the seat bucket, connected by a link and crossbar to the twin sears of the seat initiator located under the seat bucket. The seat initiator is connected by two fixed pipes attached to two trombone tube assemblies, one on either side at the rear of the seat bucket. An upward pull on the ejection handle withdraws the two sears of the seat initiator to simultaneously fire the two-seat initiator impulse cartridges CCU-105/A.

SAFE/ARMED Handle

The SAFE/ARMED handle is on the RH side of the seat bucket immediately forward of the emergency restraint release handle. A catch in the handle locks it in

either the ARMED or SAFE position. The handle is connected to a linkage terminating in a safety plunger, which passes through the link of the ejection control handle when the handle is in the SAFE position and prevents operation of the ejection control handle. In the ARMED position, the visible portion of the handle is colored with yellow and black stripes and engraved ARMED; in the SAFE position the visible portion is colored white and engraved SAFE. An electrical visual SAFE/ARMED indicator is in the cockpit central warning panel and is operated by a micro-switch actuated by the safety plunger.

Emergency Restraint Release System

The emergency restraint release handle is connected by two link assemblies to the lower harness lock release mechanism and a firing mechanism housed

2-20

Figure 2-22.—Operating controls (SJU-17(V)1/A, 2/A, and 9/A).

in the rear lower RH side of the seat bucket. The handle is locked in the down position by a catch operated by a thumb button at the forward end of the handle;

depression of the thumb button allows the handle to be rotated rearward. Handle operation when the seat is installed is restricted by the pin puller so it releases only the lower torso restraint and leg restraint lines to permit emergency ground egress. On ejection, the pin puller is automatically disengaged from the handle-operating link. Operation of the emergency restraint release handle simultaneously operates the SAFE/ARMED handle to the SAFE position. In the unlikely event of automatic sequence failure, operation of the emergency restraint release handle subsequent to ejection will fire a cartridge to operate the upper and lower harness locks and the parachute deployment rocket motor.

Shoulder Harness Control System

The shoulder harness control lever is attached to the LH side of the seat bucket and is connected by a linkage, torque tube, and rod to the shoulder harness reel. When the lever is in the forward position the shoulder harness reel is locked, preventing all forward movement of the seat occupant. When moved to the rear position, the seat occupant is free to move forward and aft at will; should the seat occupant move forward rapidly, however, the shoulder harness reel will lock until the load on the webbing straps is eased. To operate the control, the lever is moved along a quadrant until a spring-loaded plunger engages in either one of two positions in the quadrant backplate. The lever will automatically engage where selected.

2-21

Figure 2-23.—Operating controls (SJU-17(V)3/A and 4/A).

On SJU-17(V) seats 1/A, 2/A, 5/A, 6/A, and 9/A the seat height actuator switch is situated immediately forward of the shoulder harness control lever on the LH side of the seat bucket. On SJU-17(V) 3/A and 4/A the switch is situated immediately aft of the emergency restraint release handle on the RH side of the seat bucket. Forward movement of the toggle switch lowers the seat bucket, and aft movement raises the seat bucket. When released, the toggle assumes the center OFF position.