Narrative:

I reviewed an embraer disposition which was driven from a request from air carrier to replace the upper and lower rudder hinge fittings. It has become a procedure to replace the upper and lower rudder fittings one at a time on emb aircraft without the removal of the #1 and #2 rudders. In review of the disposition; the rudder backlash checks were not performed and the full adjustment and test was not performed. I was asked if a rudder backlash check needed to be performed by maintenance personnel. I told them no because of the statement note. Do this step only if you replace the #1 rudder with a new one. This is the reason that I told maintenance the backlash check was not needed. The rudders were checked for the neutral position. When it was found that the rudders were still in limits in the neutral position limits; it was felt by me that no other travel task listed needed to be performed. After the neutral check was performed; an operations check of the rudder was performed by having it operated back and forth. No defects were noted. I was the inspector performing the rii on the rudder hinge fittings replacement. I also need to state that I have also performed the rii on the upper hinge on another emb aircraft and that the same procedure was used. There is a defect on the upper and lower stabilizer to rudder hinge fittings. The defect is the delaminable washers that are used in both fittings to set up proper clearance. These washers; after a time in service; will deteriorate and separate. With the washer material missing; the gap will increase causing the clearance to increase between the hinge and attachment points. If this problem was addressed there would not be a discrepancy of hinge play on the rudder hinge fittings. The hinge fittings I saw were still svcable but maintenance opted to replace them. The problem was in the delaminable washer. The tasks that were not performed were due to the interpretation. Callback conversation with reporter revealed the following information: reporter stated this aircraft has two rudder sections. Rudder-1; most forward and rudder-2 the aft section. The issue centers around laminated washers which delaminate and migrate over time causing side to side play where the forward rudder (rudder 1) attaches to the aft side of the vertical stabilizer. There are (4) rudder attach hinges at the vertical stabilizer. Only the upper and lower hinges appear to be affected by the delamination. These washers are installed on all the hinges between the rudder hinge and the mounting bracket to the vertical stabilizer. The upper/lower laminated washers can be replaced without removing the entire forward rudder. If replacement of laminated washers are necessary at the two center hinges; then forward rudder removal is required. The aircraft mfg embraer has agreed to this procedure; but requires that all (3) checks be accomplished: the zero rig (neutral) test; the backlash test and the full adjustment test.

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Original NASA ASRS Text

Title: AN EMB-140 ACFT HAD SHIMS REPLACED UNDER RUDDER HINGE FITTINGS ON THE VERTICAL STAB WITHOUT ACCOMPLISHING THE REQUIRED RUDDER OPS CHECKS.

Narrative: I REVIEWED AN EMBRAER DISPOSITION WHICH WAS DRIVEN FROM A REQUEST FROM ACR TO REPLACE THE UPPER AND LOWER RUDDER HINGE FITTINGS. IT HAS BECOME A PROC TO REPLACE THE UPPER AND LOWER RUDDER FITTINGS ONE AT A TIME ON EMB ACFT WITHOUT THE REMOVAL OF THE #1 AND #2 RUDDERS. IN REVIEW OF THE DISPOSITION; THE RUDDER BACKLASH CHKS WERE NOT PERFORMED AND THE FULL ADJUSTMENT AND TEST WAS NOT PERFORMED. I WAS ASKED IF A RUDDER BACKLASH CHK NEEDED TO BE PERFORMED BY MAINT PERSONNEL. I TOLD THEM NO BECAUSE OF THE STATEMENT NOTE. DO THIS STEP ONLY IF YOU REPLACE THE #1 RUDDER WITH A NEW ONE. THIS IS THE REASON THAT I TOLD MAINT THE BACKLASH CHK WAS NOT NEEDED. THE RUDDERS WERE CHKED FOR THE NEUTRAL POS. WHEN IT WAS FOUND THAT THE RUDDERS WERE STILL IN LIMITS IN THE NEUTRAL POS LIMITS; IT WAS FELT BY ME THAT NO OTHER TRAVEL TASK LISTED NEEDED TO BE PERFORMED. AFTER THE NEUTRAL CHK WAS PERFORMED; AN OPS CHK OF THE RUDDER WAS PERFORMED BY HAVING IT OPERATED BACK AND FORTH. NO DEFECTS WERE NOTED. I WAS THE INSPECTOR PERFORMING THE RII ON THE RUDDER HINGE FITTINGS REPLACEMENT. I ALSO NEED TO STATE THAT I HAVE ALSO PERFORMED THE RII ON THE UPPER HINGE ON ANOTHER EMB ACFT AND THAT THE SAME PROC WAS USED. THERE IS A DEFECT ON THE UPPER AND LOWER STABILIZER TO RUDDER HINGE FITTINGS. THE DEFECT IS THE DELAMINABLE WASHERS THAT ARE USED IN BOTH FITTINGS TO SET UP PROPER CLRNC. THESE WASHERS; AFTER A TIME IN SVC; WILL DETERIORATE AND SEPARATE. WITH THE WASHER MATERIAL MISSING; THE GAP WILL INCREASE CAUSING THE CLRNC TO INCREASE BTWN THE HINGE AND ATTACHMENT POINTS. IF THIS PROB WAS ADDRESSED THERE WOULD NOT BE A DISCREPANCY OF HINGE PLAY ON THE RUDDER HINGE FITTINGS. THE HINGE FITTINGS I SAW WERE STILL SVCABLE BUT MAINT OPTED TO REPLACE THEM. THE PROB WAS IN THE DELAMINABLE WASHER. THE TASKS THAT WERE NOT PERFORMED WERE DUE TO THE INTERP. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED THIS AIRCRAFT HAS TWO RUDDER SECTIONS. RUDDER-1; MOST FORWARD AND RUDDER-2 THE AFT SECTION. THE ISSUE CENTERS AROUND LAMINATED WASHERS WHICH DELAMINATE AND MIGRATE OVER TIME CAUSING SIDE TO SIDE PLAY WHERE THE FORWARD RUDDER (RUDDER 1) ATTACHES TO THE AFT SIDE OF THE VERTICAL STAB. THERE ARE (4) RUDDER ATTACH HINGES AT THE VERTICAL STAB. ONLY THE UPPER AND LOWER HINGES APPEAR TO BE AFFECTED BY THE DELAMINATION. THESE WASHERS ARE INSTALLED ON ALL THE HINGES BETWEEN THE RUDDER HINGE AND THE MOUNTING BRACKET TO THE VERTICAL STAB. THE UPPER/LOWER LAMINATED WASHERS CAN BE REPLACED WITHOUT REMOVING THE ENTIRE FORWARD RUDDER. IF REPLACEMENT OF LAMINATED WASHERS ARE NECESSARY AT THE TWO CENTER HINGES; THEN FORWARD RUDDER REMOVAL IS REQUIRED. THE AIRCRAFT MFG EMBRAER HAS AGREED TO THIS PROCEDURE; BUT REQUIRES THAT ALL (3) CHECKS BE ACCOMPLISHED: THE ZERO RIG (NEUTRAL) TEST; THE BACKLASH TEST AND THE FULL ADJUSTMENT TEST.

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.