A B767-400 RETURNED TO THE FIELD DUE TO SLAT ASYMMETRY INDICATION AND WARNING. CAUSED BY INCORRECT INSTALLATION OF SLAT POS SENSOR TARGETS.

Narrative

A TEAM OF 4 TECHNICIANS WERE PERFORMING WORK CARD ENGINEERING AUTH XXXX; REVISION 'A;' FOR OUR FIRST TIME. THE WX WAS A MASSIVE TSTM WITH HIGH WINDS AND RAIN. THE LOCATION WAS ON THE 'B' CHK PAD DARK UP ON A LIFT TRUCK. THE PAPERWORK WAS CONFUSING ON THE SLAT POS TO PERFORM THE WORK. THE REF MATERIAL AT FIGURE 023 WAS MISLEADING OF THE SENSOR TARGET REMOVE AND TO BE INSTALLED. IT TOOK 4 TECHNICIANS TO REMOVE AND INSTALL THE BEARINGS AND TARGETS (WASHERS); 2 APPLYING PRESSURE TO THE SLATS AND 2 TO INSTALL THE BEARING AND ALIGN THE BOLTS AND TARGETS. I WAS UNABLE TO SEE THE TARGET REMOVED OR INSTALLED FROM THE POS I WAS AT APPLYING PRESSURE TO THE SLAT. THE 2 TECHNICIANS REMOVING AND INSTALLING THE BEARINGS AND TARGETS WERE XXX AND YYY. THE OTHER TECHNICIAN APPLYING PRESSURE WAS ZZZ. DURING ALL THE WX CONDITIONS; THE 2 TECHNICIANS SOMEHOW INSTALLED THE TARGETS IN THE OPPOSITE POS. I CHKED THE CORRECT TORQUE ON THE BOLTS; AND VERIFIED THE CORRECT GAP BTWN THE SENSORS AND TARGETS; 'A' SYS TEST 767-400 AMM 27-81-02/501 WAS PERFORMED AND PASSED BY XXX. (THE ACFT EXPERIENCED A SLAT ASYMMETRY INDICATION ON A SUBSEQUENT FLT AND RETURNED TO THE DEP ARPT.)