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

a. An automatic seal (e.g. check valve) shall maintain vessel pressure if the aircraft-supplied pressure source is removed. An automatic or manually operated seal shall maintain pressure if

the ground supplied pressure source is removed.

b. A mechanical method to prevent over-pressurization of the pressure vessel shall be provided. Examples are a mechanical relief valve or a burst disc.

c. The release and ejection system shall be initiated remotely by independent aircraft electrical power sources (primary and secondary). Independent initiation circuits shall follow separate wirings to activate redundant energy source control devices. Examples are the use of two solenoids for the same function or a solenoid with dual coils, with each coil wired independently to the aircraft (see Figure 5). Ejection performance shall not be affected by the loss of either primary or secondary aircraft electrical power source.

d. In order to enable the aircraft release control system to initiate release with sufficient pressure to achieve safe store separation, the BRU shall provide pressure vessel status. An example is a pressure transducer integral to the BRU that supplies a signal to the aircraft's stores management system.

e. A method to bleed all stored pneumatic or hydraulic pressure from the BRU. This device shall be manually operated, but the use of common hand tools normally available on the flight line is acceptable.

f. After store release or ejection, all downstream pressure from the pressure vessel shall vent.

g. The release control device operation shall be designed to ensure that once the store release process has been initiated it shall not be possible to interrupt it until safe store separation has been achieved.

h. The BRU in conjunction with its safety interlock shall provide a method to safely load and unload stores with its pressure vessel charged.

i. For pneumatic BRUs, the gas used for pressure vessel filling shall be industrial nitrogen, (A-A-59503, type I, grade B) or air containing less than 15 ppm of water containing no solid particles over 5 µm in length. If the BRU pneumatic supply source cannot meet the 15 ppm requirement for water contamination, then its design shall account for the effects of stress corrosion in high pressure vessels due to water condensation.

j. For hydraulic BRUs, the fluid used for pressure vessel filling shall be specified by the procuring activity.