A B737-300 ON APCH HAD THE TRAILING EDGE FLAPS STOP DUE TO ASYMMETRICAL SHUTOFF. FOUND FLAP DRIVE 90 DEG ANGLE GEARBOX COUPLING CAME APART.

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I REMOVED THE R ANGLE GEARBOX FIRST. INSTALLED THE R ANGLE GEARBOX AFTER SAFETY WIRING THE LONG WHEEL WELL TORQUE TUBE TO IT. PUT 1 SCREW IN THE SHORT 90 DEG TORQUE TUBE. I ALSO PUT 1 SCREW IN THE OTHER END OF THE LONG TORQUE TUBE IN THE CTR OF THE WHEEL WELL. NEXT I REMOVED THE 120 DEG GEARBOX AND REINSTALLED IT ONLY PUTTING 1 SCREW IN EACH COUPLING BECAUSE WE WERE RUNNING OUT OF TIME. I WAS TOLD BY MY LEAD MECH NOT TO SAFETY WIRE IT OR PUT IN THE REMAINING SCREWS BECAUSE IT STILL NEEDED TO BE RIGGED BY SHOPS. I FILLED OUT THE FORM FOR THE 120 DEG GEARBOX AND MY LEAD MECH FILLED THE CARD FOR THE 90 DEG GEARBOX. I HANDED THE REMAINING SCREWS OVER TO A SHOPS MECH WHOSE NAME I DON'T KNOW. WHEN I LEFT THE PLANE THAT MORNING ALL THE INSPECTION PANELS WERE STILL OFF AS WELL AS BOTH OF THE INBOARD FLAP TRACK FAIRINGS. WE PUT ALL OF THESE IN THE REAR CARGO BIN. AS FAR AS THE GEARBOXES GO ALL COUPLINGS EXCEPT FOR THE 90 DEG COUPLING ENTERING THE WHEEL WELL HAD ONLY 1 SCREW IN EACH COUPLING. THE 90 DEG COUPLING ENTERING THE WHEEL WELL HAD ALL 3 SCREWS AND WERE LOCK-WIRED TOGETHER. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE AIRPLANE OPERATED FOR 7 DAYS AFTER RELEASE FROM THE TRAILING EDGE FLAP GEARBOX REPLACEMENT WORK. THE CAUSE OF THE TRAILING EDGE SHUTDOWN WAS ASYMMETRICAL AS 1 FLAP WAS LEADING THE OTHER SIDE. MAINT DISCOVERED ONE 90 DEG GEARBOX COUPLING HAD COME APART FROM THE TORQUE TUBE DRIVE.