FMU-143E/B ELECTRIC TAIL FUZE

The FMU- 143E/B fuze (fig. 1-11) is used with the GBU-24B/B. It is initiated by the FZU-32B/B initiator which is used to generate and supply power to arm the fuze. The safe condition is verified by the presence of a safety pin or arming wire through the pop-out pin (gag rod).

FMU-139 (SERIES) ELECTRONIC BOMB FUZE

The FMU-139 (series) electronic bomb fuze (fig. 1-12) is an electronic impact or impact-delay fuze. It is used in Mk 80 series general-purpose bombs, including laser guided bombs. The arming times are in-flight selectable, and the functioning delay must be set during weapon assembly. There are three arming times (2.6, 5.5, and 10.0 seconds) and four functioning delay settings (10, 25, and 60 milliseconds, and instantaneous). Only 2.6/60, 2.6/25, 2.6/10, and 2.6/inst high drag arm/delay switch positions are authorized for Navy/Marine Corps use. The low drag arm time switch should always be in the X position. The low drag arm time rotary switch is positioned at X for shipping, storage, and all FFCS (fuze function control set) use. The FMU-139 fuze differs from the Mk 344 and Mk 376 fuzes in that the gag rod and arming wire housing are located in the center of the faceplate (fig. 1-13).

Figure 1-11.-FMU-143E/B electric tail fuze,

Figure 1-12.-FMU-139 (series) electronic bomb fuze.

Figure 1-13.-FMU-139 (series) electronic bomb fuze gag rod in safe and unsafe positions.