Narrative:

I was assigned to replace a jackscrew scheduled parts change on air carrier X. I have never accomplished this task. While accomplishing the task card I disconnected the drum cable stb and wound on a spool. During that operation the stb cable was allowed to go slack because the mechanic I was working with having done this before thought that the cable on the front spool had cable guides that wouldn't allow it to slip from the spool. There was difficulty in winding with the other mechanic in the control cabin putting pressure on the trim wheel so instead of him continuing to apply pressure he was used to unwind the cable from the control cabin. After completely unwinding the cabin and disconnecting from the drum a cable block was installed on the sta side cable. At different points sta cable had been allowed to go slack. After swing shift put the new jackscrew in the cables were reattached and tensioned, not realizing they had slipped on the front drum and crossed. They subsequently kinked and were damaged beyond service. After hearing of the event I looked at the maintenance manual 27-41-81 page 405 and saw a warning about allowing the cable to become slack. There is no such warning on the task card. Callback conversation with reporter revealed the following information: the reporter stated the job was started using the stabilizer jackscrew replacement job card and not the maintenance manual. The job card does not have the warning about allowing body cables stb and sta to go slack and cable blockers must be used. Later in the job the cables were tensioned and were kinked damaging the cables which were scrapped. The reporter admitted the error in not blocking the cables which is standard procedure in any rigging job. A request was made to revise the job card to add the warning not to allow the cables to go slack.

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Original NASA ASRS Text

Title: A B737-400 DURING THE STABILIZER JACK REPLACEMENT THE TECHNICIAN ALLOWED CABLES STB AND STA TO GO SLACK WITH NO CABLE BLOCKS INSTALLED.

Narrative: I WAS ASSIGNED TO REPLACE A JACKSCREW SCHEDULED PARTS CHANGE ON ACR X. I HAVE NEVER ACCOMPLISHED THIS TASK. WHILE ACCOMPLISHING THE TASK CARD I DISCONNECTED THE DRUM CABLE STB AND WOUND ON A SPOOL. DURING THAT OP THE STB CABLE WAS ALLOWED TO GO SLACK BECAUSE THE MECH I WAS WORKING WITH HAVING DONE THIS BEFORE THOUGHT THAT THE CABLE ON THE FRONT SPOOL HAD CABLE GUIDES THAT WOULDN'T ALLOW IT TO SLIP FROM THE SPOOL. THERE WAS DIFFICULTY IN WINDING WITH THE OTHER MECH IN THE CTL CABIN PUTTING PRESSURE ON THE TRIM WHEEL SO INSTEAD OF HIM CONTINUING TO APPLY PRESSURE HE WAS USED TO UNWIND THE CABLE FROM THE CTL CABIN. AFTER COMPLETELY UNWINDING THE CABIN AND DISCONNECTING FROM THE DRUM A CABLE BLOCK WAS INSTALLED ON THE STA SIDE CABLE. AT DIFFERENT POINTS STA CABLE HAD BEEN ALLOWED TO GO SLACK. AFTER SWING SHIFT PUT THE NEW JACKSCREW IN THE CABLES WERE REATTACHED AND TENSIONED, NOT REALIZING THEY HAD SLIPPED ON THE FRONT DRUM AND CROSSED. THEY SUBSEQUENTLY KINKED AND WERE DAMAGED BEYOND SVC. AFTER HEARING OF THE EVENT I LOOKED AT THE MAINT MANUAL 27-41-81 PAGE 405 AND SAW A WARNING ABOUT ALLOWING THE CABLE TO BECOME SLACK. THERE IS NO SUCH WARNING ON THE TASK CARD. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE JOB WAS STARTED USING THE STABILIZER JACKSCREW REPLACEMENT JOB CARD AND NOT THE MAINT MANUAL. THE JOB CARD DOES NOT HAVE THE WARNING ABOUT ALLOWING BODY CABLES STB AND STA TO GO SLACK AND CABLE BLOCKERS MUST BE USED. LATER IN THE JOB THE CABLES WERE TENSIONED AND WERE KINKED DAMAGING THE CABLES WHICH WERE SCRAPPED. THE RPTR ADMITTED THE ERROR IN NOT BLOCKING THE CABLES WHICH IS STANDARD PROC IN ANY RIGGING JOB. A REQUEST WAS MADE TO REVISE THE JOB CARD TO ADD THE WARNING NOT TO ALLOW THE CABLES TO GO SLACK.

Data retrieved from NASA's ASRS site as of July 2007 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.