AN ACR DC8-70 FREIGHTER CREW HAD AN INFLT ENG SHUTDOWN. THE FUEL BOOST PUMP WAS 'OFF.'

Narrative

PASSING FL350; #3 ENG N1 STARTED FLUCTUATING +/-3 PERCENT; AT FIRST. OVER A SHORT PERIOD OF TIME; THE FLUCTUATIONS GOT MUCH WORSE. ATTEMPTS TO STABILIZE THE ENG WERE UNSUCCESSFUL. THE FO NOTED THAT HE HAD LOST CTL OF THE ENG; BY THE THROTTLE; SHORTLY THEREAFTER. WE DID AN INFLT ENG SHUTDOWN AND; BEING UNABLE TO MAINTAIN ALT; DSNDED AND TURNED BACK TO SDF. WHILE DSNDING; THE SO NOTED THAT THE #3 BOOST/FEED SWITCH WAS IN THE 'OFF' POS. AN INFLT RESTART WAS ATTEMPTED AT FL310; BUT WAS UNSUCCESSFUL. PASSING FL190; IN A DSCNT; ANOTHER INFLT ENG START WAS ATTEMPTED. THE ENG STARTED NORMALLY. DURING THE RETURN FLT TO SDF; THE ENG OPERATED NORMALLY. WHEN THE PROB FIRST STARTED; THE FLUCTUATIONS OF THE ENG; ALONG WITH DROPPING OIL PRESSURE; LED ME TO BELIEVE THE ENG MIGHT BE 'EATING ITSELF.' I FELT THE SAFEST COURSE OF ACTION WAS A 'PRECAUTIONARY ENG SHUTDOWN.' AFTER THE #3 BOOST/FEED SWITCH WAS DISCOVERED TO BE 'OFF;' MY THOUGHTS WERE THAT THE ENG HAD NOT SHOWN WHAT WOULD BE CONSIDERED INDICATIONS OF FUEL STARVATION. IT WAS MY JUDGEMENT; THAT THE SAFEST COURSE OF ACTION; WAS TO RETURN TO OUR POINT OF ORIGINATION AND HAVE THE ENG CHKED OUT. THE SWITCH IN QUESTION IS NORMALLY 'COVERED' WITH A RELATIVELY LARGE PLASTIC KNOB INDICATING ITS FUNCTION. THE KNOB WAS MISSING FOR THIS FLT AND LISTED AS A 'DEFERRED ITEM' AS PER OUR COMPANY MAINT PROCS. THIS DID MAKE THE SWITCH HARDER TO SEE AND SUBSEQUENTLY IT WAS OVERLOOKED DURING NORMAL CHKLIST FLOWS. SUPPLEMENTAL INFO FROM ACN 354792: I NOTICED THE #3 BOOST PUMP SWITCH; WITHOUT THE LARGE PLASTIC KNOB; OFF. I TRIED TO MOVE THE SWITCH TO THE ON POS; WHICH I DID; AND THE BOOST/FEED LIGHT ILLUMINATED AND THEN WENT OUT; INDICATING THAT FUEL PRESSURE WAS BEING PROVIDED TO THE #3 ENG. I CHKED THE LARGE; PLASTIC KNOB ON THE BOOST PUMP SWITCH IMMEDIATELY NEXT TO THIS SWITCH; THE CTR-WING AUX BOOST PUMP SWITCH AND IT WAS ON. IT SHOULD NOT HAVE BEEN ON BECAUSE THERE WAS NO FUEL IN THIS TANK. DURING MY BEFORE ENG START CHKLIST PROCS; I SCANNED THE BOOST PUMP SWITCHES AS I TURNED THEM ON. I DID NOT GRAB A SWITCH; TURN IT ON; CONFIRM THE FUEL PRESSURE GAUGE WAS INDICATING PRESSURE; AND THEN PROCEED TO THE NEXT SWITCH; AS I SHOULD HAVE. CONTRIBUTING FACTOR: MY HASTE IN ACCOMPLISHING THE CHKLIST AND PERFORMING THIS PORTION IN A PERFUNCTORY MANNER. THE LARGE PLASTIC KNOB WAS MISSING. THIS DID MAKE THE SWITCH HARDER TO SEE AND IT WAS OVERLOOKED DURING NORMAL CHKLIST FLOWS.