AN SMT PLT NOTICED THAT HIS AUTOFEATHER SYS WAS NOT WORKING QUITE RIGHT. MAINT SAID THAT IT WAS ALL RIGHT; THEN AFTER 1 OR MORE FLT; MAINT FOUND THAT WRONG PART HAD BEEN INSTALLED AT THE MAINT BASE.

Narrative

DURING AUTOFEATHER TEST ON FIRST FLT OF THE DAY; SYS FUNCTIONED PROPERLY BUT NOT WITHIN PARAMETERS ESTABLISHED BY COMPANY. I CALLED THE LCL OPS STATION AND ASKED THEM TO CALL MAINT CTL. AFTER DISCUSSING THE PROBLEM; MAINT CTL SAID IT WAS SIMPLY A SMALL VARIATION IN THE WAY THAT PARTICULAR ACFT AUTOFEATHER TESTED AND THAT THE ACFT COULD BE RELEASED FOR OUR FLT. UPON ARR AT OUR MAINT STATION; MECH CAME ONBOARD AND AFTER DISCUSSING PROBLEM HE TOLD ME THAT THAT WAS NOT THE PROBLEM HE HAD BEEN TOLD OF DURING THE PHONE CONVERSATION. THE PROBLEM WAS THAT THERE WERE 2 HIGH PRESSURE SWITCHES INSTALLED ON THE AUTOFEATHER SYS RATHER THAN 1 HIGH AND 1 LOW PRESSURE SWITCH. THE ACFT HAD BEEN TO 1 MAINT BASE ON MM/DD/92 AND THE MISTAKE IN PARTS PROBABLY OCCURRED AT THAT TIME. THE FLT WAS NOT COMPROMISED BECAUSE THE AUTOFEATHER DID FUNCTION PROPERLY. THE FLT WAS UNEVENTFUL AND THE PROBLEM WAS CORRECTED PRIOR TO NEXT FLT. PROBLEM COULD HAVE BEEN AVOIDED IF I HAD SPOKEN DIRECTLY TO A MECH IN ORDER TO DISCUSS THE PROBLEM. ALSO ACFT SHOULD HAVE NEVER BEEN RELEASED FROM MAINT BASE BECAUSE SYS WOULD NOT TEST WITHIN PARAMETERS. COMPANY SHOULD PUBLISH AND DISCUSS WITH PLTS MORE DEFINED PARAMETERS AND STRICTER FOLLOW-UP WHEN HUMAN ERROR IN ACFT MAINT IS OBSERVED.