What was found
A/C CANNOT HOLD FL350 WITH THREE TC'S ON, CABIN WILL CLIMB PAST 10,000 FT HAD TO DESCENT TO FL310. OPS CK ON GRND NORMAL MM 21-31-0, ADVISE CREW COMMENTS. AIRCRAFT DUE GROUND PRESSURIZATION CHECK. PRESSURIZED AIRCRAFT ON GROUND. PRESSURIZATION WAS WITHIN LIMITS ON GROUND. OPS CHECK GOOD IAW DC8 MM 21-31-0.