A B727 WAS DISPATCHED WITH AN INTERMITTENT CAPT'S VERT SPD INDICATOR.

Narrative

WE WERE SUPPOSED TO FLY THIS ACFT ON SCHEDULED FLTS FROM CVG TO ALB TO PWM TO ALB TO CVG. UPON TAXI OUT FOR ALB- PWM LEG; CAPT'S VSI FAILED. AFTER TROUBLESHOOTING ON TXWY PROVED UNSUCCESSFUL AND WE FOUND IT WAS A NO GO ITEM; WE RETURNED TO GATE AND CALLED CONTRACT MAINT. THE VSI JUST STARTED WORKING AS WE STOPPED AT GATE. HE FOUND NOTHING WRONG; SIGNED OFF LOGBOOK AND WE FLEW TO PWM. UPON PUSHBACK IN PWM FOR ALB; VSI FAILED AGAIN. WE RETURNED TO GATE. IT STAYED OUT FOR 20 MINS. CONTRACT MAINT WAS CALLED. I CALLED THE COMPANY MAINT COORDINATOR AND DECISION WAS MADE TO SHIP PART FROM BOS BECAUSE SYMPTOMS OF TROUBLE SOUNDED LIKE A FAILURE MODE. PART NEVER MADE IT AS PROMISED. PAX WERE REROUTED. MAINT COORDINATOR (NEW ONE) ASKED US TO TAKE PLANE IF MECH AFTER INSPECTING EVERYTHING SIGNED IT OFF. SAID I WOULD FERRY IT IF VSI WORKED TO THE POINT OF DISPATCH. HE TRIED TO TALK ME INTO TAKING ACFT UNDER PART 91 REGARDLESS OF IT WORKING. I REFUSED. WE DID TAKE PLANE DIRECTLY TO CVG WITHOUT PAX AFTER MECH HAD US START ENGS AT GATE AND SHIFT PWR BACK AND FORTH WITHOUT FAILURE. WHEN WE SHIFTED PWR TO GATE IN CVG; VSI FAILED AGAIN.