Narrative:

Aircraft is in for a check working on engineering order for left wing outboard bellcrank assembly modification. Problem of bellcrank aft flap push rod and aft flap drive rod were hooked up in reverse position 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 check for looseness and same for step B. Callback conversation with reporter revealed the following information: reporter 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.

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Original NASA ASRS Text

Title: 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.

Data retrieved from NASA's ASRS site as of January 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.