Lowell, They don't need a deviation and I don't believe they applied for one as the new TSO only applies to new models designed and submitted after the effective date of the TSO. So they can continue to make and sell hook and loop mountings on all their previously TSO'd ELT's.
However Kannad did issue a vague service bulletin: https://www.mcmurdogroup.com/wp-cont...mechanisms.pdf
It requires firmly strapping and pulling on the unit to see if it will come out and visual inspection for wear and tear. Whoopie!
My point was, the NTSB wanted all hook and loop mounts to be eliminated and still could push for that to happen as they didn't get it in the current 126b - as it only has to be implemented on NEW elt designs submited for TSO after 11/26/12. Part of the reason some elt manufacturers aren't improving and redesigning their products since 2012.
Why install a $400 more expensive product when the concensus (stated in the TSO and by the NTSB) states: the use of hook and loop fasteners is not an acceptable means of attachment.
BTW, a dedicated 121 tuned external antenna will not optimally (if at all, depending on the antenna) transmit a 406 signal.
Greg