Mechanical Fuzing System for Aircraft Bombs

The fuze has a selective arming time delay of 4 to 20 s, marked in 2 s intervals from 4 to 8 s and in 4 s intervals from 8 to 20 seconds. The striker is activated by inertia instead of impact.

Arming is effected by the vane arming assembly M772 through the rotation action of the flexible drive connected to the coupler drive assembly which reduces the high revolutions of the arming drive to a constant speed output of approximately 1800 revolutions per minute. The coupler drive assembly accepts the torque from the flexible drive shaft and transmits it to the attached tail fuze.

The fuze is made up of two main assemblies, the input drive housing assembly and the fuze body assembly.

This fuze may be used for impact and impact-delay application in conjuction with nose fuze M904 and forms the tail component of the fuzing system for unguided and guided bombs.

CSD M905


A safety pin prevents the vanes of the arming drive assembly from rotating. An instruction label attached to a red tag and safety pin states that after the arming wire has been inserted in the drive assembly the safety pin is to be removed, and replaced if the bomb is not dropped.

The safety features of the fuze are the same as for the nose fuze M904 except that a white stripe appears in the large inspection windows at all arming delay settings.


The MK-80 series bombs use a mechanical impact fuze. The detonation of MK bombs occurs when the explosive train progress through the fuze, which in turn detonates the booster and the main charge of the bomb. Each bomb may carry two fuzes: a Nose Fuse M904 and a Tail Fuze M905.


Total length with booster – 230 mm

Body maximum diameter – 62.5 mm

Delay element – M9 (no delay)

The fuze weight with the booster – 1.3 kg

Reduction of the mechanism – 972:2

Selections times to arm – 2 to 18s

Arming time tolerance – ± 20%

Initiation by – Impact

Shelf life – 10 years

Service life – 5 years

Put action by – Drive assembly ATU-35/B

Operation temperature – -40°C to + 50°C

Storage temperature – -10°C to + 40°C

Bomb interface – Standard NATO 2” 12 Un 2A. Fits into M148 adapter booster or similar

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