Narrative:

Approximately 30 mins after departure, crew called and said they needed 5 units left rudder trim to stabilize aircraft, and that right aileron was up and not faired. This was causing the rudder trim problem. Upon arrival on gate I noticed right aileron bus cable badly frayed and broken in two. It had worn away on the back side of the pulley just inboard of right main landing gear. This cable is approximately 3/16 inch in diameter. There was much dirt and grime on the cable and pulleys due to its location in gear well. Left side was also inspected and found to be ok. This rudder trim problem had been reported previously (2 times or more) but reports made no mention of any flight control position nor did they give confign details such as flap setting, airspeed, wind direction, etc. Upon our inspection or service check done prior to this departure, and prior crew report of rudder trim problem, we could only find a spacer block missing from the right outboard fore flap carriage assembly which was replaced. Aircraft was brought to gate for departure at XA00. Callback conversation with reporter revealed the following information: reporter stated the aircraft was a B737-300 with ge cfm 56-3 engines. The reporter described the cable as being frayed and worn and extremely saturated with dirt, sand, and grit. The reporter advises the cable pulleys and leads were svcable and no interference to the cable was noted. The reporter believes the area where the cable was broken and frayed was never cleaned and being just outside of the wheel well could accumulate the dirt and sand thrown up by the landing gear. The reporter stated the left side cable area was clean and no wear noted.

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Original NASA ASRS Text

Title: A B737-300 RETURNED TO THE FIELD DUE TO EXCESSIVE RUDDER TRIM INPUT TO STABILIZE THE ACFT AND ON INSPECTION IT WAS DISCOVERED THAT THE R AILERON BUS CABLE WAS FRAYED AND BROKEN.

Narrative: APPROX 30 MINS AFTER DEP, CREW CALLED AND SAID THEY NEEDED 5 UNITS L RUDDER TRIM TO STABILIZE ACFT, AND THAT R AILERON WAS UP AND NOT FAIRED. THIS WAS CAUSING THE RUDDER TRIM PROB. UPON ARR ON GATE I NOTICED R AILERON BUS CABLE BADLY FRAYED AND BROKEN IN TWO. IT HAD WORN AWAY ON THE BACK SIDE OF THE PULLEY JUST INBOARD OF R MAIN LNDG GEAR. THIS CABLE IS APPROX 3/16 INCH IN DIAMETER. THERE WAS MUCH DIRT AND GRIME ON THE CABLE AND PULLEYS DUE TO ITS LOCATION IN GEAR WELL. L SIDE WAS ALSO INSPECTED AND FOUND TO BE OK. THIS RUDDER TRIM PROB HAD BEEN RPTED PREVIOUSLY (2 TIMES OR MORE) BUT RPTS MADE NO MENTION OF ANY FLT CTL POS NOR DID THEY GIVE CONFIGN DETAILS SUCH AS FLAP SETTING, AIRSPD, WIND DIRECTION, ETC. UPON OUR INSPECTION OR SVC CHK DONE PRIOR TO THIS DEP, AND PRIOR CREW RPT OF RUDDER TRIM PROB, WE COULD ONLY FIND A SPACER BLOCK MISSING FROM THE R OUTBOARD FORE FLAP CARRIAGE ASSEMBLY WHICH WAS REPLACED. ACFT WAS BROUGHT TO GATE FOR DEP AT XA00. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THE ACFT WAS A B737-300 WITH GE CFM 56-3 ENGS. THE RPTR DESCRIBED THE CABLE AS BEING FRAYED AND WORN AND EXTREMELY SATURATED WITH DIRT, SAND, AND GRIT. THE RPTR ADVISES THE CABLE PULLEYS AND LEADS WERE SVCABLE AND NO INTERFERENCE TO THE CABLE WAS NOTED. THE RPTR BELIEVES THE AREA WHERE THE CABLE WAS BROKEN AND FRAYED WAS NEVER CLEANED AND BEING JUST OUTSIDE OF THE WHEEL WELL COULD ACCUMULATE THE DIRT AND SAND THROWN UP BY THE LNDG GEAR. THE RPTR STATED THE L SIDE CABLE AREA WAS CLEAN AND NO WEAR NOTED.

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.