SUBCALIBER PRACTICE BOMBS

The practice bombs normally used on a routine basis are the Mk 76 Mod 5 and the BDU-48. These practice bombs are discussed briefly in the following paragraphs.

Mk 76 Mod 5 Practice Bomb

The Mk 76 Mod 5 practice bomb (fig. 13-13) is prepared for aircraft loading as discussed in the following steps:

Figure 13-13.-Mk 76 Mod 5 practice bomb. 13-13

WARNING

Be extremely careful when handling a practice bomb loaded with a signal. Jarring or dropping the bomb may detonate the signal. Do not, under any circumstances, point either end of the bomb toward another person. Loading personnel must not place their bodies in line with the nose or tail end of a bomb.

1. Remove the bomb from the cardboard container.

2. Remove the cotter pin and Mk 1 firing-pin assembly from the nose. Inspect it for rust and deformation. Ensure the firing-pin cup is not deformed and the firing-pin point is below the lip of its cup.

3. Inspect the blast tube for rust and obstructions. Clean as required. When any obstructions are noted, proceed as follows: Insert a plug gauge SK923AS503 into the center cavity. The gauge should slide into place until the shoulder rests flush against the bomb. When the gauge shoulder does not rest against the bomb, the cavity is not clear. When the obstruction cannot be removed, reject the bomb as unserviceable, and dispose of it by following current instructions.

WARNING

A signal cartridge must not be swollen or deformed in any manner. The primer must be flush with or slightly below the base of the cartridge. If you attempt to install a deformed signal, it can cause detonation. Use extreme care when you handle a signal cartridge. When a practice bomb is not used

after the signal has been installed, the signal must be gently removed and replaced in the original shipping container. The cartridge can be reloaded and used later. Do not apply pressure to force the signal cartridge or firing-pin assembly into the bomb because the assembly could become deformed and fire the signal.

4. With the firing-pin assembly removed, elevate the nose of the bomb. Insert the Mk 4 Mod 3 or CXU-3A/B practice bomb signal, primer end up, into the nose of the practice bomb. Slide it gently into place. Do not use force. The base flange of the signal cartridge must rest on the bore shoulder, which is about 1 1/4 inches inward from the nose of the bomb.

5. Carefully insert the firing-pin assembly with the firing-pin end toward the signal.

6. Rotate the firing-pin assembly so that the two notches in the lip of the forward cup line up with the cotter pin holes in the nose end of the bomb. Do not apply pressure to the firing pin during this procedure.

7. Insert the cotter pin through the pinholes in the bomb body. Pass it through the notches in the firing-pin assembly. Spread the ends of the cotter pin just enough to retain it in place.

BDU-48 Practice Bomb

The BDU-48 practice bomb is prepared for aircraft loading as discussed in the following steps:

NOTE: The warnings discussed for the Mk 76 Mod 5 also apply to the BDU-48.

Figure 13-14.-BDU-48/B practice bomb.

1. Remove the bomb assembly from the container.

2. Remove the firing device and inspect for rust or deformation. Refer to figure 13-14 for identification of the components.

3. Inspect the blast tube for rust and deformation. Clean as required.

4. Insert the signal into the sleeve. With the firing device removed, elevate the nose of the bomb. Insert the Mk 4 or CXU-3A/B practice bomb signal, primer end up, and slide it gently into place. Do not use force. The base flange of the signal cartridge must rest on the bore shoulder.

5. Carefully insert firing pin assembly into the nose of the bomb.

6. Align firing pin assembly notches with the two holes in the nose end of the bomb. Insert cotter pin through holes in bomb body, and spread end of cotter pin just enough to remain in place.

For detailed information concerning the preparation of practice bombs for aircraft loading, refer to the publication NAVAIR 11-140-5.