A MECHANIC; UPSET ABOUT HIS LEAD SENDING EXTRA PEOPLE TO HELP HIM; TRIES TO COMPLETE A MAIN ENG OIL FILTER CHANGE ON A DEHAVILLAND DHC8-400 BY HIMSELF TO SHOW INDEPENDENCE. MECHANIC INSTALLS WRONG O-RING IN OIL FILTER.

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I WAS GIVEN ACFT X INITIALLY AS A LINE CHK BY MY GRAVE LEAD; ABOUT XA00. COME XA15; LEAD STATED THAT MAINT CTL HAS TAKEN BACK THE LINE CHK AND JUST TO DO THE MEL'S LISTED FOR THE AIRPLANE. I HAD ALREADY STARTED THE LINE CHK BY SEEING IF THERE WERE ANY FAULTS LISTED. UPON BRINGING THEM UP; FAULT 915 WAS LISTED FOR ENG #1. I HAD SEEN THIS BEFORE AND DONE THE PROC FOLLOWING THIS TYPE OF FAULT MANY TIMES BEFORE AND WAS EAGER TO SHOW MY INDEPENDENCE TO DO 'LARGE' JOBS BY MYSELF. THE FIM STATES THAT THE MAIN OIL FILTER NEEDS TO BE CHANGED. TASK 79-22-06-XXXX-XX. HOWEVER; HE SENT OUT TECHNICIAN Y AND TECHNICIAN Z TO ASSIST ME. THEY WERE AT THE END OF THEIR SWING SHIFT. I HAD ANNOUNCED TO BOTH OF THEM AND MY LEAD THAT I HAD DONE THIS JOB BEFORE AND WILL BE DOING IT. IT WAS; AFTER ALL; ON 'MY' SHIFT; I THOUGHT. I TOOK DOWN THE HOUSING; FILTER AND CLEANED UP THE OIL MESS IT LEAVES WHEN YOU YANK IT OUT OF ITS PLACE AND HANDED THE HOUSING FILTER TO TECHNICIAN Z AND TECHNICIAN Y WHO WERE STANDING BY TO TAKE IT AND CHANGE IT OUT. IN AN EFFORT TO TRY TO COMPLETE THE TASK MYSELF AND SHOW INDEPENDENCE; I SHOWED WRONG JUDGEMENT.