CHAPTER 2

AUTOMATIC OPENING DEVICES

Learning Objective: Upon completion of this chapter, you will be able to recognize, inspect, and maintain cartridges and cartridge-actuated devices used with personnel emergency parachute assemblies.

As you look around the parachute loft, you will see that it is a very clean, neat, and safelooking place to work. Although it has this appearance, there are a few places that are very dangerous. One of the more hazardous places is the packing table. The packing table may look as safe to you as sitting at home in your easy chair watching television. However, on the packing table you will find automatic opening devices. There are two basic opening devices used in the operation of personnel parachutes.

The first is the automatic parachute ripcord release. Working with this actuator is the same as working with a loaded .38 caliber pistol. The second is the ballistic spreader gun. This gun has a cartridge; and when fried, it gives the same effect as an exploding hand grenade. Working with any opening device requires extreme caution-all safety precautions must be taken to ensure your safety as well as that of your coworkers. This chapter will help you understand the operation, function, and maintenance of this equipment.

AUTOMATIC PARACHUTE ACTUATORS

The Navy currently uses the Model 7000 automatic parachute ripcord release (fig. 2-1) in its personnel parachute assemblies. It is a barometrically controlled, pyrotechnic device. The actuator is designed to open a parachute at a preset altitude. The Model 7000 automatic parachute ripcord release is available with two different altitude settings. One is the 10,000-foot setting, plus or minus 1,000 feet (identified by green labels on the cover assembly). The aneroid is identified by a green potting seal and a white

Figure 2-1.-Model 7000 Automatic Parachute Ripcord Release.

label with green lettering. The other is the 14,000-foot setting, plus or minus 1,000 feet (identified by red labels on the cover assembly). The aneroid is identified by a red potting seal and a white label with red lettering.

FUNCTION

It is impossible for an aircrewman to select the altitude at which an emergency may occur. By using the automatic ripcord release, you can bring the aircrewman down to a safe altitude before the parachute opens.

When an aircrewman makes an emergency ejection at an altitude above that for which the ripcord release is set to open the parachute, the following functions take place:

1. The arming pin is pulled. This pin locks the ripcord release firing mechanism while installed. When the arming pin is withdrawn, the assembly fires at or below the preset altitude of the ripcord release.

2. The sear and the aneroid mechanism lock the ripcord release.

3. As the aircrewman free-falls, increasing air pressure causes the aneroid to contract.

4. As the operating altitude is reached, the aneroid contracts enough to remove the sear from the firing hammer lock.

5. The hammer's firing pin strikes the cartridge.

6. The time-delay cartridge fires (time depending on the type of cartridge used) after the hammer strikes.

7. The piston is forced forward in the barrel, pulling the power cable, which is attached to the parachute locking pins. (The power cable travels 3.75 inches.)

8. The locking pins are pulled, and the normal parachute opening sequence begins.

When an aircrewman bails out below the operating altitude of the automatic parachute ripcord release, the hammer releases as soon as the arming pin is pulled, and the following functions take place:

1. The hammer's firing pin strikes the cartridge.

2. The time-delay cartridge fires (time depending on the type of cartridge used) after the hammer strikes.

3. The piston is forced forward in the barrel, pulling the power cable, which is attached to the parachute locking pins.

4. The locking pins are pulled, and the normal parachute opening sequence begins.