A B737-700 ACFT LH OUTBOARD AFT FLAP INCURRED DAMAGED DURING A BELLCRANK MODIFICATION. TITANIUM CONNECTING RODS WERE INSTALLED INCORRECTLY AND BROKE.

Narrative

ACFT IS IN FOR A CHK WORKING ON ENGINEERING ORDER FOR L WING OUTBOARD BELLCRANK ASSEMBLY MODIFICATION. PROB OF BELLCRANK AFT FLAP PUSH ROD AND AFT FLAP DRIVE ROD WERE HOOKED UP IN REVERSE POS AND WHEN MOVING FLAPS THE RODS BROKE AND CAUSES DAMAGE TO AFT FLAP. AS INSPECTION GOES FOR STEPS IS TO INSTALL AND TORQUE HARDWARE NUTS AND CHK FOR LOOSENESS AND SAME FOR STEP B. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THE BELLCRANK BEING REPLACED IS A HEAVIER (BEEFIER) UNIT ON ALL OF HIS COMPANY'S B737-700; LH AND RH WING. THIS BELLCRANK CAN BE ROTATED 360 DEGREES; NO MASTER SPLINE; SO MECHANICS MUST POSITION THIS BELLCRANK AND NOT BE 180 DEGREES OUT WHILE MAKING SURE THEY HAVE THE CORRECT (HEAVIER) END OF THE CONNECTING RODS POSITIONED INTO THE BELLCRANK. NO MARKINGS EXISTS ON THESE RODS TO INDICATE WHICH END CONNECTS TO THE BELLCRANK. ALTHOUGH THE CONNECTING RODS ARE MADE OF TITANIUM; THE INCORRECT INSTALLATION AND MOVEMENT OF THE FLAPS ENDED UP STILL SHEARING BOTH RODS. THE HEAVIER MODIFIED BELLCRANK WAS NOT DAMAGED. AS A RESULT; IMPROVEMENTS HAVE BEEN MADE IN THE PAPERWORK; PICTORIALS AND ADDED NOTE ITEMS FOR MECHANICS AND INSPECTORS TO BE AWARE OF DURING RE-ASSEMBLY.