Narrative:

During pre flight actions on feb/sat/04 with aircraft X and Y at ZZZ, I discovered an elevator flight control cable (pilots side) chaffing on a guide support assembly. According to the model 750 maintenance manual, 20-10-20 page 201, this cable is called a lockclad cable assembly. The maintenance manual provides the following criteria for inspecting the lockclad cable assemblies for wear. Note: the lockclad may be worn completely through as long as the cable has not started to wear or fray. If a cable with worn lockclad is discovered, the worn area of the lockclad must be blended (tapered out) as necessary with a file or sandpaper to prevent it from snagging on the structure. You must then determine the cause for the wearing of the lockclad and correct by clearing any interference. I must now mention, that with the auxiliary pump selected 'on' and my first officer manipulating the control yoke forward and aft, I witnessed the lockclad cable bounce off the bracket as the wear notch moved forward and aft across the top portion of the support bracket assembly. It appeared to be catching the bracket, which was ultimately interfering with the operation of the lockclad cable as it moved back and forth. This area of concern has never been brought to my attention by flight school, a check airman, management, or even a fellow pilot. If gone unchallenged, this could become an extremely dangerous situation in due time. Callback conversation with reporter revealed the following information: the reporter stated in making an inspection of the aft equipment bay left lower side a control cable was observed laying on top of a guide support bracket. The reporter said the cable covering and the bracket both appeared to be chaffed with the cable covering worn to the control cable wire. The reporter stated the cable is called a lockclad cable assembly and has wear limits on the cable covering and wire strands. The reporter said the first officer was instructed to put hydraulics on the airplane and move the yoke and the cable assembly wear notch was observed moving across the bracket in a sawing motion. The reporter stated this was reported to main management and a logbook writeup was made and follow up information from maintenance revealed two types of brackets are stocked. The reporter stated the two brackets are stocked by the manufacturer with the same part number, so ordering a bracket may, or may not get a modified bracket that would prevent chaffing or the same bracket already installed. The reporter said the same problem exists in at least 10 airplanes checked in the last few months, one with only 300 hours.

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Original NASA ASRS Text

Title: A CESSNA 750 CAPT RPTS FINDING THE CAPTS ELEVATOR CABLE IN THE LOWER ACFT EQUIP BAY L SIDE CHAFFING ON A BRACKET. LOCKCLAD COATING WORN THROUGH THE BARE CABLE.

Narrative: DURING PRE FLT ACTIONS ON FEB/SAT/04 WITH ACFT X AND Y AT ZZZ, I DISCOVERED AN ELEVATOR FLT CTL CABLE (PLTS SIDE) CHAFFING ON A GUIDE SUPPORT ASSEMBLY. ACCORDING TO THE MODEL 750 MAINT MANUAL, 20-10-20 PAGE 201, THIS CABLE IS CALLED A LOCKCLAD CABLE ASSEMBLY. THE MAINT MANUAL PROVIDES THE FOLLOWING CRITERIA FOR INSPECTING THE LOCKCLAD CABLE ASSEMBLIES FOR WEAR. NOTE: THE LOCKCLAD MAY BE WORN COMPLETELY THROUGH AS LONG AS THE CABLE HAS NOT STARTED TO WEAR OR FRAY. IF A CABLE WITH WORN LOCKCLAD IS DISCOVERED, THE WORN AREA OF THE LOCKCLAD MUST BE BLENDED (TAPERED OUT) AS NECESSARY WITH A FILE OR SANDPAPER TO PREVENT IT FROM SNAGGING ON THE STRUCTURE. YOU MUST THEN DETERMINE THE CAUSE FOR THE WEARING OF THE LOCKCLAD AND CORRECT BY CLEARING ANY INTERFERENCE. I MUST NOW MENTION, THAT WITH THE AUX PUMP SELECTED 'ON' AND MY FO MANIPULATING THE CONTROL YOKE FORWARD AND AFT, I WITNESSED THE LOCKCLAD CABLE BOUNCE OFF THE BRACKET AS THE WEAR NOTCH MOVED FORWARD AND AFT ACROSS THE TOP PORTION OF THE SUPPORT BRACKET ASSEMBLY. IT APPEARED TO BE CATCHING THE BRACKET, WHICH WAS ULTIMATELY INTERFERING WITH THE OPERATION OF THE LOCKCLAD CABLE AS IT MOVED BACK AND FORTH. THIS AREA OF CONCERN HAS NEVER BEEN BROUGHT TO MY ATTENTION BY FLIGHT SCHOOL, A CHECK AIRMAN, MANAGEMENT, OR EVEN A FELLOW PLT. IF GONE UNCHALLENGED, THIS COULD BECOME AN EXTREMELY DANGEROUS SITUATION IN DUE TIME. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED IN MAKING AN INSPECTION OF THE AFT EQUIP BAY LEFT LOWER SIDE A CONTROL CABLE WAS OBSERVED LAYING ON TOP OF A GUIDE SUPPORT BRACKET. THE RPTR SAID THE CABLE COVERING AND THE BRACKET BOTH APPEARED TO BE CHAFFED WITH THE CABLE COVERING WORN TO THE CONTROL CABLE WIRE. THE RPTR STATED THE CABLE IS CALLED A LOCKCLAD CABLE ASSEMBLY AND HAS WEAR LIMITS ON THE CABLE COVERING AND WIRE STRANDS. THE RPTR SAID THE FO WAS INSTRUCTED TO PUT HYDRAULICS ON THE AIRPLANE AND MOVE THE YOKE AND THE CABLE ASSEMBLY WEAR NOTCH WAS OBSERVED MOVING ACROSS THE BRACKET IN A SAWING MOTION. THE RPTR STATED THIS WAS RPTED TO MAIN MANAGEMENT AND A LOGBOOK WRITEUP WAS MADE AND FOLLOW UP INFORMATION FROM MAINT REVEALED TWO TYPES OF BRACKETS ARE STOCKED. THE RPTR STATED THE TWO BRACKETS ARE STOCKED BY THE MANUFACTURER WITH THE SAME PART NUMBER, SO ORDERING A BRACKET MAY, OR MAY NOT GET A MODIFIED BRACKET THAT WOULD PREVENT CHAFFING OR THE SAME BRACKET ALREADY INSTALLED. THE RPTR SAID THE SAME PROB EXISTS IN AT LEAST 10 AIRPLANES CHECKED IN THE LAST FEW MONTHS, ONE WITH ONLY 300 HOURS.

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.