What was found
DUCT PRESSURE INDICATIONS BETWEEN L AND R WERE SPLIT UP TO 18PS L=23 PSI R=41PSI FL 38.0 N1=L89.5/R89.5 N2=L92.3/R92.3 FF=L2.63/R2.63 SAT = 55C TAT= 28C PRIOR TO TOP OF DESCENT THE SPLIT REDUCED TO < 8PSI R39 L=32PSIGI. PERFORMED PNEU HEALTH CHECK ON NR 1 ENG. FOUND PRSOV WITH A BLOWN DIAPHRAM + INLINE CONTROL PRESS AT 17 PSI WITH PS AT 70 PSI. BLEED AIR REG FAILED CONTROL PRESS TEST & PRESS SWITCH FAILED PS = 220 WITH PC AT 12 PSI REF AMM 36 11 00. REPLACED REF 36 11 04. REPLACED BLEED AIR REGULATOR REF AMM 36 11 03. PERFORMED TOTAL SYSTEM ENG BLEED AIR SYSTEM HEALTH CHECK. REF: AMM 36 11 00. OPS CHECK GOOD.