If an aircraft does not have an FDR, must one be installed to comply with Flight Data Monitoring requirements in EASA countries? Flight Data Monitoring (FDM), which analyzes FDR data to accomplish things like ensuring that pilots are following SOP's, is a requirement for EASA's Third Country Operators (TCO) certification, however certain (older) aircraft do not seem to require an FDR.

Does this effectively change the requirement so that an FDR must be installed in an aircraft in order to accomplish FDM or is there an exception for FDM as well?  I have been unable to find anything specifically addressing this.
For 20 PAX and more, it becomes mandatory.

https://www.lepoint.fr/sport/le-piper-malibu-un-avion-delicat-22-01-2019-2287804_26.php


  Les boîtes noires sont obligatoires sur les appareils de transport public d'au moins vingt sièges.