locking pin for use with the long-delay fuze. This pin
locks the adapter booster to the base plug of the bomb
and prevents removal of the adapter booster while the
fuze is installed. The M150 has a yellow band around
the adapter booster casing, which indicates that it is
loaded with explosives.
ELECTRICAL FUZES
LEARNING
OBJECTIVE:
Identify
the
various types of electrical fuzes to include their
physical description and functional operation.
The Mk 376 (fig. 1-6) electric bomb fuze provides
an all-electric capability for the Mk 80 (series) bombs
with either conical or retarding fins, thermally
protected bombs, and laser-guided bombs (LGB).
Electric fuzes require an electric pulse from the aircraft
fuze function control (FFC) system. The FFC gives
in-flight selection of function delay and arming delay
times. The 376 fuze is used with the Mk 43
target-detecting device for airburst capability.
DESCRIPTION
The Mk 376 Mod 0 electric tail fuze is detonator
safe. The booster contain 4.3 ounces of tetryl explosive.
This fuze is classified HERO SAFE, and no unusual
RADHAZ precautions are required under normal
operating conditions.
Four discreet dc voltages for in-flight selection of
functioning delay times are used in the Mk 376 fuze.
The Mk 31 safety device automatically selects arming
delay times.
MK 31 SAFETY DEVICE
The Mk 31 safety device is used to adapt the fuze to
the fuze well of the bomb, provide mechanical safing of
the fuze, and unlock the timer-decelerometer. The
safety device contains a pop-out pin that locks the fuze
in an unarmed condition. The spring-loaded pin is held
in the safe position by either a safety cotter pin or an
arming wire. When the weapon is released from the
aircraft, the arming wire is pulled from the pop-out pin,
allowing the pin to pop out, unlock the decelerometer,
thus initiating the arming time. When the free-fall mode
of delivery is used the Mk 376 fuze, arming is
completed 10.0 seconds after release from the aircraft.
If the Mk 31 safety device senses weapon deceleration
(Snakeye fins open), the internal circuits of the fuze are
switched, and the fuze becomes armed in 2.6 seconds.
The quicker arming time is required to ensure the fuze
is fully armed for low-altitude delivery. If deceleration
is not sensed by 2.6 seconds, the fuze arming delay
continues to the 10.0-second arming time.
FUNCTIONAL OPERATION
The following description applies specifically to
the Mk 376 fuze.
Two arming delays are used in the Mk 376
fuze—2.6 seconds for retarded delivery and 10.0
seconds for unretarded delivery. The appropriate
arming delay is automatically selected by the fuze
according to the actual delivery mode of the weapon.
That is, if the weapon does not retard, whether
intentionally or unintentionally, the fuze automatically
provides a 10.0-second arming delay.
At release, the arming wire is withdrawn and a
charging voltage (+300, +195, -195, or -300 Vdc) is
applied to the fuze. The pilot selects the voltage in flight
by the fuze function control set located in the cockpit.
The fuze polarity and level of the fuze charging voltage
is important only with respect to functioning delay.
1-10
Figure 1-6.—Mk 376 Mod 0 electric fuze.
