FLC OF ACR MLG ACFT RETURNED TO LAND AFTER LOSING OIL ON 1 ENG CAUSED BY IMPROPER MAINT.

Narrative

THE MAINT CREW CHANGED AN ENG DRIVEN FUEL PUMP ON MLG ACFT. I WAS THE LEAD MECH ON SHIFT AND WAS WORKING OVERTIME TO RETURN 2 ACFT TO SVC. WE HAD A MECH WHO WAS UPGRADED TO INSPECTOR TO BUY OFF THE RII ON THE PUMP INSTALLATION. NEAR THE END OF THE SHIFT THE INSTALLATION WAS COMPLETE AND FAILED THE LEAK CHK BECAUSE THE FUEL CTL WAS LEAKING FUEL. THE FUEL CTL WAS REMOVED AND A SEAL WAS REPLACED. MEANWHILE THE SUPVR OF DAY SHIFT HAD SENT THE INSPECTOR HOME OFF THE GRAVEYARD SHIFT. I DID NOT KNOW THAT THE INSPECTOR HAD LEFT. THE FUEL CTL WAS REPLACED AND A LEAK CHK WAS PERFORMED BY A MECH. THE ACFT WAS TAKEN FOR A PWR ASSURANCE RUN AND RETURNED TO THE GATE READY FOR THE SCHEDULED FLT. I ASKED THE MECHS WAS THE INSTALLATION INSPECTED AND THEY ASSURED ME IT WAS DONE. AFTER LOOKING FOR THE INSPECTOR WHO HAD GONE HOME I THOUGHT HE HAD JUST FORGOT TO SIGN HIS NUMBER ON THE PAPERWORK. SO I SIGNED OFF THE ROUTINE PAPERWORK FOR A SCHEDULED PUMP CHANGE THINKING THAT HE HAD JUST FORGOT TO PUT HIS NUMBER ON THE PAPERWORK. THE CREW CALLED AND SAID THEY HAD AN OIL LEAK ON THE SAME ENG THAT THE PUMP WAS CHANGED. I WENT TO THE AIRPLANE AND ANOTHER MECH WAS ALREADY THERE. IT SEEMED TO APPEAR THAT THE OIL WAS OVERSVCED BECAUSE WHEN HE TOOK THE OIL CAP OFF; OIL RAN OUT. WE CHKED THE CSD AND STARTER AND THEY CHKED FINE. THE CREW DID NOT ENTER A DISCREPANCY IN THE LOGBOOK. I TOLD THEM THE OIL APPEARED TO BE OVERSVCED. THE ACFT DEPARTED AND RETURNED (AIR TURN BACK) WITH OIL QUANTITY DROPPING IN THE SAME ENG AS THE FUEL PUMP CHANGE. UPON FURTHER INVESTIGATION THE FUEL PUMP DRIVE SHAFT WAS FOUND (PINCHING) AN O-RING. IT WAS REPLACED AND THE ACFT RETURNED TO SVC. THE CONFUSION AT SHIFT CHANGE WAS TREMENDOUS. THE A-SHIFT SUPVR HAD LEFT AND THE B-SHIFT SUPVR WAS ON DUTY. I WAS NOT INFORMED THAT A B-SHIFT PERSON WOULD PERFORM THE RII INSPECTION AND WAS UNDER THE IMPRESSION THAT THE UPGRADED A-SHIFT INSPECTOR HAD PERFORMED THE INSTALLATION AND LEAK CHK INSPECTION AS REQUIRED AND HAD FORGOT TO SIGN THE PAPERWORK IN HIS HASTE TO LEAVE WORK. THAT'S WHEN I WROTE HIS NUMBER ON THE CARD. HAD I KNOWN THE EVENTS THAT TOOK PLACE THIS WOULD HAVE NEVER HAPPENED. THE SHIFT TURNOVER CAN BE HECTIC AND COMS CAN GET A LITTLE JUMBLED. THAT IS EXACTLY WHAT LED TO THIS INCIDENT.