I sent an email to the Program Manager, New Technologies Development Approval and Certification Center Mine Safety and Health Administration

asking about the Dry Spell for Approvals (not one since May 16th)

The reply:

There is no specific reason for that "dry spell" in communications and tracking system approvals. We have a number that are very close to being issued, but still needing some additional testing and/or evaluation. Approval issuances, like everything, else can experience dry spells. I don't believe summer holidays are a significant factor because we have only had a few of our investigators take any time off so far this summer. I do anticipate that there will be several approvals issued before the end of June.