What was found
CLIMB THRU FLT LEVEL 180 CABIN PRESS START TO DECREASE AT 1200 RPM (4.8 PSID & DECREASING). PERFORMED CABIN PRES CKLIST, NO HELP. *S/D* ACCOMPLISH EXCESS CABIN PRESS LEAKAGE CONDITION, REF B727 MM 05-51-101-2, TEST OK. NO DEFECTS NOTED AT THIS TIME, A/C OK FOR SERVICE.