A B737-300 REQUIRED AN AIR TURNBACK DUE TO LANDING GEAR HANDLE WOULD NOT MOVE TO THE 'UP' POSITION. INSPECTOR AND MECHANIC ARE NOTIFIED THAT A DIODE WAS INSTALLED BACKWARDS ON THE LANDING GEAR HANDLE SOLENOID.

Narrative

TODAY I WAS NOTIFIED OF AN EVENT THAT OCCURRED WITH AN AIR TURN-BACK. THE HANDLE WOULD NOT RAISE THE GEAR AND WOULD NOT MOVE TO THE 'UP' POS. AFTER THE ACFT WAS TAKEN OTS; IT WAS FOUND THAT A DIODE WAS INSTALLED BACKWARDS ON THE LNDG GEAR HANDLE SOLENOID. IT WAS UNKNOWN TO ME THAT THE DIODE COULD BE INSTALLED BACKWARDS. IT WAS RELAYED TO ME THAT THIS IS A KNOWN PROB; BUT AS OF NOW NOTHING HAS BEEN DONE TO ADDRESS IT. I ENTERED A MAINT ALERT TO BRING A WARNING TO THE MECH THAT IT IS POSSIBLE TO INSTALL IT BACKWARDS. SUPPLEMENTAL INFO FROM ACN 778051: REMOVED AND REPLACED LNDG GEAR SOLENOID. MAINT MANUAL AND THE FIGURE ON THE PAPERWORK DOES NOT SHOW DIODE AND DOES NOT SAY ABOUT INSTALLING THE DIODE ON A CERTAIN LOCATION. PERFORM OPS CHK ACCORDING TO MANUAL. NO PROB. FOUND INSPECTION CHK JOB ACCOMPLISH. ALSO IT WAS DISCOVERED UPON TKOF; LNDG GEAR HANDLE WILL NOT COME UP AND THEY DID AN AIR RETURN. CAME BACK TO THE GATE AND REMOVED AND REPLACED SOLENOID. SAME PROB. GEAR HANDLE WILL NOT COME UP. REVERSE THE DIODE AND THEN IT PASSED THE TEST. PAPERWORK DOES NOT STATE OR MENTION THE DIODE AT ALL.