PFRX means Preflight Relmat
X-1,2,3...9 or A,B,C...Z in
NASA
Similar to PFRX
AAD - Attitude Anomaly Detector
AAFE - AeroAssist Flight Experiment
AAFM - Acoustic Atomic Force Microscopy
AAR - After Action Review
AARL - Aeronautical and Astronautical Research Laboratory
AAV - Air Admittance Valve
AAV - Aerospace Audio- Visual
View all in NASA