Yup, its all operator specific. I've worked for airlines that required the CB
, for both CVR and FDR, pulled and I've worked for operators that insist (checklist item) that they are in.
On reflection, in the past ten years or so, as the industry has moved from tape based to digital based recorders, the tendency to pull the CB
has gone away. My guess is that since we (maintenance) are not eating into the life of the CVR or FDR recording medium, our operators will insist that the recorders are operative in case of a problem, so the "tapes" can be reviewed.