Desco - Questions And Answers

1) If I have AVIONIC units that are capped and plugged and wrappedin ESD protective packaging; is it safe to place those items on a metal shelf (no rubber/shelf matting of any kind) and in close (almost touching) proximity to another avionic unit next to it? #2) Same scenarion but what if it isn't in ESD wrapping but has the caps and plugs? -Anonymous, Miramar, Florida

The answer is not that straight forward. If the AVIONIC unit is capped and plugged then is should be fairly safe with the following assumptions: 1- I assume in this state there are no electrically exposed inputs/outputs to the unit, 2- The AVIONIC unit’s outer housing is metal or conductive, 3- The caps and plugs are dissipative, 4- The caps and plugs, if in intimate contact with any input/output cables/contacts are shunting all connections at once. With the above conditions met, then the unit should be fairly safe in an ESD package on a metal shelf. The concerns to address/control here are:- if the unit becomes charged and is then is placed on a metal shelf, whether grounded or not, it will discharge (Charge Device Model - CDM)- if the units are handled without ESD protective packaging by an ungrounded operator who places them on the metal shelf, may present ‘charged’ units expose their neighbors to electric fields or possible CDM concerns (see above) one way to take care of these concerns would be to have the people who handle the inventory to wear foot grounders with an ESD floor. Further precautions can include using grounded dissipative material to line the shelves with. These two solutions would only be necessary if this AVIONCS device was extremely sensitive and/or Expensive to replace.

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