RR_NDB;
Are they installed adjacent and with the same orientation? CSMU´s to the front and chassis box to the rear of a/c
The SSFDR is installed 2 frames aft of the rear pressure bulkhead and the SSCVR is installed 2 frames forward of the aft L/H door. Both are installed with the interface box facing forward and the CSMU aft. The BEA has published details of their placement, and a search of their website will provide you with the documentation.