FLC FAILED TO HAVE REQUIRED MAINT INSPECTION FOR AN MEL ITEM PRIOR TO DEP.

Narrative

FLT PAIRING I WAS FLYING INCLUDED A SCHEDULED ACFT CHANGE. ACFT THAT I CHANGED TO; HAD 4 MEL'S. 1 MEL WAS FOR THE STANDBY HYD SYS QUANTITY LIGHT INOP. ACCORDING TO OUR COMPANY MEL; MAINT AS DENOTED BY AN (M) WAS TO VISUALLY CHK THE HYD FLUID QUANTITY PRIOR TO EACH DEP. THIS WAS ACCOMPLISHED IN PHX PRIOR TO MY ARR AT ACFT. AN ENTRY WAS MADE IN THE LOGBOOK SAYING THAT FLUID WAS ADDED TO THE SYS. PRIOR TO DEP FROM PHX; I NOTIFIED DISPATCH TO ARRANGE FOR CONTRACT MAINT TO MEET ACFT UPON ARR IN DEN TO VISUALLY INSPECT HYD SYS QUANTITY. FLT WAS LATE ARRIVING DEN BECAUSE OF ENRTE HOLDING DUE TO ADVERSE WX (SNOW AND ICE). WHILE ON THE GND IN DEN PREPARING FOR DEP I INADVERTENTLY FORGOT TO HAVE CONTRACT MAINT CHK HYD SYS QUANTITY. MY COPLT AND COMPANY DISPATCH AND MAINT ALSO FORGOT. I VISUALLY CHKED QUANTITY WHILE ACCOMPLISHING WALK-AROUND INSPECTION AT DEN. TKOF CHKLIST ALSO REQUIRES INSPECTION OF HYD SYS QUANTITY GAUGE. BOTH CHKS SHOWED THAT QUANTITY WAS OK. I FLEW ACFT BACK TO PHX WITHOUT INCIDENT OTHER THAN POSSIBLE MISSING A LOGBOOK ENTRY. CONTRIBUTING FACTORS: FOURTH DAY OF CONSECUTIVE FLYING. DUTY TIME APCHING 12 HRS. ADVERSE WX LEADING TO ENRTE HOLDING; ACFT DE-ICE WHILE ON GND AT DEN (FIRST TIME FOR ME THIS WINTER SEASON). PERFORMANCE CONSIDERATIONS AS ACFT HAD AN INTERMIX OF ENGS (MINUS 15 AND MINUS 9A). ALSO POSSIBLE OVER GROSS WT FOR RWY CONDITIONS.