What was found
3926 AT ALTITUDE OBSERVED THAT HYD SYS WAS AT APPROX 2400 PSI AND 60% QTY, DECREASING PRESSURE AND FLUCTUATION. WHEN PRESSURE WAS AT 1800 PSI, RAN APPROPIATE QRH PROCEDURE. DIVERTING TO SDF. DURING DESCENT NOTICED LARGE FLUCTUATIONS IN HYD 1 PRESSURE FROM 1600 PSI-3200PSI. TEMP AND QTY WITHIN LIMITS. AIRCRAFT REMOVED FROM SERVICE PERFORMED OPS CHECK OF ACMP 1B IAW AMM 29-11-03. OPS CHECK GOOD. C/W O ACTION OF MEL 29-31-01. OPS CHECK GOOD. REF 311313/2/3 FOR MELS BRYAN TUTT A&P 3606587 COULD NOT DUPLICAT. REMOVED AND REPLACED #1 SYS PRESSURE TRANSDUCER. OP'S AND LEAK CHECKS GOOD. REF AMM29-11. REMOVED PLACARD, REMOVED FROM MEL S/N OFF: 8257-8-111 S/N ON: 8545-10-50