MIL-STD-2088-SUP-2 Bomb Rack Unit BRU, Single Store, AircraftThis standard establishes the general guidelines and criteria for the design and development of a single store bomb rack unit BRU for carriage and release of airborne stores excluding air-to-air missiles from fixed wing and rotary wing aircraft using a single suspension point or suspension points spaced at 14 or 30 inches. This standard addresses detailed requirements for gravity non-ejected, pyrotechnic, hydraulic, and pneumatic powered BRUs. Mechanical aircraft armament interoperable interfaces are incorporated to enhance cross utilization and servicing capabilities between military aircraft and aircraft stores see 3.1 of all services of the Department of Defense DoD and North Atlantic Treaty Organization NATO nations.

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MIL-STD-2088B

5.1.2.2 Vertical support latching security. The vertical support latch mechanisms shall be designed to prevent the inadvertent release of a store under any of its operational environments. Adequate margin to prevent unlatching shall be determined based on the resultant forces acting on the vertical support latch mechanism assuming worst case dynamic load conditions and using the worst case design physical dimensions.

a. Worst case dynamic load conditions shall consider aircraft dynamic flight environments, swaybrace performance, harmonic oscillation of the latch drive linkage, and potential load transients.

b. Worst case design physical dimensions shall include the worst case assumptions of machining tolerances, adjustment and alignment capabilities, life time material wear, and potential aircraft environment contamination build-up.

5.1.3 Store sensing. The BRU shall provide remote indication of store presence status (store present signal), which is not susceptible to a single point failure providing an incorrect status. The sensing device shall provide a logic signal to the control system identifying store presence status. Store sensing shall ensure that a hung store retained by only one vertical support is sensed as a store present.

5.1.3.1 Store sensing failure mode. Mechanical or electrical failure of the store sensing device shall be in the fail-safe mode (store not present).

5.1.4 Fuzing and arming control. The BRU design shall include integral, mechanical, and electrical fuze Arming Units (AUs) to control the "SAFE/ARM" function of fuzes on appropriate conventional stores. The BRU shall be capable of independent operation of each AU. All

arming wire-to-AU connection points shall be easily accessible with the store fully latched and restrained. All locations shall be as specified in 5.1.4.1 and 5.1.4.2, and interface connections shall comply with MIL-STD-8591. Additionally, the BRU design shall include positive arming attachment points as specified in 5.1.4.3.

5.1.4.1 Mechanical fuze AUs. The BRU shall provide up to three continuous duty electromechanical AUs to control the store mechanical fuze(s) "SAFE/ARM" functions. The AUs shall be mechanically linked to the BRU (AIR STD 20/17) latching mechanism with provisions for the following:

a. An energized AU shall retain an arming wire with a minimum force of 600 pounds.

b. With vertical latching mechanism closed, shall retain arming wire to preclude preload problems during captive carriage (AU not energized and BRU vertical supports closed).

c. Shall allow zero retention force on arming wire when store is released and

AUs are "safe" or not energized.