Adapter Boosters

Install adapter boosters by using the procedures discussed in the following text.

WARNING

Fuzing for the thermally protected GP/TP bomb to obtain cook-off protection is limited to Fuze M904E4 with thermally protected adapter-booster M148E1, electric fuzes FMU-139, Mk 376, and Mk 346 with thermal shield. Any other fuzing greatly increases the probability of early detonation of a bomb engulfed in a fire.

INSTALLATION OF ADAPTER BOOSTERS.- Remove the adapter booster from the shipping container. If a mechanical nose fuzing is used, install an M148 adapter booster. If you use a mechanical tail fuze, install the M150/T46 adapter booster with the booster cup.

NOTE: In addition to the booster cup, the M150 and T46 adapter booster consists of two separate explosive components. The primary adapter booster contains a 2.0-inch diameter tail fuze. The T46 (series) contains a fuze adapter sleeve for use with 1.5-inch diameter fuzes.

MECHANICAL NOSE FUZING.- When you use mechanical nose fuzing, an M148 adapter booster is installed as follows:

1. Unpack the adapter booster and remove the closing plug.

2. Inspect the adapter booster internally and externally to ensure all parts, including threads, are clean and undamaged

3. Inspect the bomb nose fuze cavity.

4. Loosen the setscrew in the bomb body.

5. Screw the adapter booster into the bomb, and tighten it with a spanner wrench until it is firmly seated

6. Tighten the setscrew in the bomb body against the adapter-booster threads.

Installation of Electric and Electronic Tai1 Fuzes

The Mk 376/FMU-139 series electric and electronic tail fuzes are currently being used in the Navy. The following are general procedures you should

follow when working with these fuzes. Refer to figure 13-6 for arming wire installation.

MK 376 ELECTRIC TAIL FUZE.- Prepare, inspect, and install the fuze as follows:

1. Ensure that the safety pin is installed in the pop-out pin.

2. Remove shipping cap.

3. Ensure moisture or foreign material is not present in the electrical connector at base of fuze.

4. With thumb, push in on pop-out pin, remove safety pin from pop-out pin.

5. Ascertain if resistance from pop-out pin against thumb is present.

6. Reinstall safety pin into pop-out pin.

7. Loosely install fuze restraining clip on the flange of the fuze.

8. Install fuze into tail fuze well, and tighten with spanner wrench until flange is seated.

9. Align pop-out vertical with bomb lugs; tighten fuze restraining clip.

FMU-139 ELECTRONIC TAIL FUZE.-

Prepare, inspect, and install the fuze as follows:

1. Ensure that gagrod is secured by safety pin.

2. Verify that red and black striping is not visible on gagrod sleeve.

3. Check fuze for exterior damage, moisture, and corrosion.

4. Remove plastic shipping plug and flag from connector on the end of the fuze.

5. Set the fuze switches as follows:

a. Check that the low-drag arm/delay fire switch is set to X-position.

b. Rotate high drag arm/delay time switch as required. It must be in a 2.6 sec position for Navy/Marine aircraft.

6. Align faceplate with bomb lugs. Insert fuze into tail fuze well.

7. Install and tighten closure ring. The fuze may spin slightly.

Mk 122 Arming Safety Switch

Remove, inspect, and install the Mk 122 arming safety switch as follows:

1. Remove the Mk 122 arming safety switch from its package.

2. Inspect the Mk 122 arming safety switch for deformation, corrosion, and damage to the case. Check the contact assembly for cleanliness. Check the coaxial cable for cracks and breaks in the insulation, and be careful not to stress the coaxial cable.

3. Install the Mk 122 safety arming switch as follows:

WARNING

The Mk 122 arming safety switch must be installed in a RADHAZ-free environment Do not pull the lanyard during handling and loading. If the lanyard breaks away from the switch, discard the entire arming safety switch so it will not be used on a bomb. Do not attempt to replace the lanyard.

CAUTION

When installing or removing the weapons carrier and while handling the weapon, be particularly careful to avoid damaging the safety switch. When using a Mk 49 Mod 1 weapons carrier, do not install the safety switch until the weapon has been positioned on the skid adapter. Failure to orient the switching unit retaining nut can result in damage to the arming safety switch.

a. Plug the male connector of the switching unit firmly into the bomb charging receptacle, piercing the diaphragm. Then, slide the switching unit retaining nut, threads down, over the cable and lanyard.

b. Secure the arming safety switch in the bomb charging receptacle by screwing the switching unit retaining nut into the bomb and tightening it with the wrench supplied. When the nut is seated on the top of the switching unit, back it off until the flattened sides of the switching unit retaining nut are at right angles to the length of the bomb and the coaxial cable is aft of the lanyard.

c. Insert the free end of the cable through the nearest bomb suspension lug to safeguard the cable.

Figure 13-6.-Mk 376 and FMU-139 series electric/electronic fuze arming wire installation.