506.6-11 scope

1.1 Purpose

The purpose of this Method is to help determine the following with respect to rain, water spray, or dripping water:

• a. The effectiveness of protective covers, cases, and seals in preventing the penetration of water into the materiel.
• b. The capability of the materiel to satisfy its performance requirements during and after exposure to water.
• c. Any physical deterioration of the materiel caused by the rain.
• d. The effectiveness of any water removal system.
• e. The effectiveness of protection offered to a packaged materiel.

1.2 Application

Use this Method to evaluate materiel likely to be exposed to rain, water spray, or dripping water during storage, transit, or operation. If the materiel configuration is the same, the immersion (leakage) test (Method 512.6) is normally considered to be a more severe test for determining if water will penetrate materiel. There is generally no need to subject materiel to a rain test if it has previously passed the immersion test and the configuration does not change. However, there are documented situations in which rain tests revealed problems not observed during immersion tests due to differential pressure. Additionally, the immersion test may be more appropriate if the materiel is likely to be placed on surfaces with significant amounts of standing water. In most cases, perform both tests if appropriately identified in the life cycle profile.

1.3 Limitations

• a. When a requirement exists for weapon system components such as seeker windows/radomes, nose cones, airframes, leading edges, control surfaces, thermal protection systems, and fuzes to operate during weather encounter to include high speed flight through hydrometeors, a tailored test approach must be utilized based on the system configuration, trajectories, and system specific statistically based weather occurrence. Traceability must be addressed between realistic flight through weather and ground test methods to ensure adequate performance characterization is achieved. Ground test methods include the use of nylon bead impact, single water drop impact, whirling-arm impact, ballistic gun ranges, and sled track facilities with rain field simulation capability to induce high speed/hypersonic integrated rain impact/erosion effects on flight components. For hypersonic item testing consider utilizing the methods described in Technical Report AMR-PS-08-01.
• b. Because of the finite size of the test facilities, it may be difficult to determine atmospheric rain effects such as on electromagnetic radiation and propagation.
• c. This Method is not intended for use in evaluating the adequacy of aircraft windshield rain removal provisions.
• d. This Method doesn't address pressure washers or decontamination devices.
• e. This Method may not be adequate for determining the effects of extended periods of exposure to rain, or for evaluating materiel exposed to only light condensation drip rates (lower than 140 L/m²/hr) caused by an overhead surface. For this latter case, the aggravated humidity cycle of Method 507 will induce a significant amount of free water on both inside and outside surfaces.