A DC-8 CAPTAIN DESCRIBES HOW THE PRE TAKEOFF CHECKLIST FOR THE RUDDER HYD PRESSURE 'DROP-RISE' CHECK FAILED THREE TIMES; YET THE LINE MECHANIC SIGNED-OFF THE LOGBOOK EACH TIME WITHOUT ANY CORRECTIVE ACTION.

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WHILE TAXIING FOR DEP; FOLLOWING A DELAYED ENG START AND WHILE ACCOMPLISHING THE BEFORE TKOF CHKLIST PROCS; THE RUDDER WOULD NOT TEST IN ACCORDANCE WITH DC8 FOM REQUIRED PRETKOF CHKLIST PROCS. AS PER THE DC8 FOM: CHK RUDDER FOR FREEDOM OF MOVEMENT. THE CAPT FIRMLY HOLDS THE NOSEWHEEL IN PLACE WITH THE STEERING WHEEL AND ACTUATES THE RUDDER PEDALS FULL R AND L. SO MONITORS THE HYD PRESSURE AS THE RUDDER DEFLECTS; FOLLOWED BY A RISE AS THE RUDDER IS FULLY DEFLECTED; AND RETURNS TO NEUTRAL. CAPT ANNOUNCES 'R RUDDER; NEUTRAL;' THEN 'L RUDDER; NEUTRAL;' AND SO ANNOUNCES 'DROP-RISE' AS IN THE AILERON CHK. RUDDER MUST MOVE FREELY WITH NO BINDING. THE DROP-RISE IS INDICATED AS A CHANGE IN PRESSURE ON THE MAIN HYD SYS PRESSURE GAUGE AS THE RUDDER DEFLECTS. USING THIS REQUIRED AND TRAINED PROC PRIOR TO FLT; THE AILERON CHKED; THE RUDDER DID NOT. NO ALTERNATE PROC OR DEV IS LISTED IN THE MEL/CDL. WE CONTINUED TO CYCLE ALL HYD USER SYS; IN ALL CONCEIVABLE VARIATIONS AND/OR COMBINATIONS AS DIRECTED BY MAINT. WE CONTACTED MAINT OPS AND WORKED OUR SECOND ATTEMPT AT TROUBLESHOOTING UNTIL IT WAS ADVISED THAT WE RETURN THE AIRPLANE TO THE RAMP TO ALLOW THE MECHS TO REVIEW THE PROB. WE ENTERED THE NON-COMPLIANT CONDITION/DISCREPANCY IN THE ACFT LOGBOOK AND ADDITIONALLY DEMONSTRATED THE PROB TO THE ATTENDING ZZZ MECHS. IT IS STANDARD OPERATING PROC FOR ANY ENTRY NOTING A REPETITIVE MECHANICAL ERROR; ESPECIALLY ON A FLT CTL SYS; TO REQUIRE A CORRECTIVE ACTION AND NOT MERELY A 'COULD NOT DUPLICATE' OR 'OPS CHKED NORMAL' RESPONSE IN THE MECH RESPONSE SECTION. THIS FAILURE/DISCREPANCY WAS REPEATED 100% OF THE TIME. THE FLT CREW REPEATED THE TEST IN THE PRESENCE OF THE ZZZ MECHS; WITH ALL NOTING THAT NOTHING WAS REGISTERED DURING ANY TEST; AS REQUIRED ON THE SYS PRESSURE GAUGE. SHORTLY; MAINT PERSONNEL AGAIN INFORMED US THAT THE ACFT WAS GREEN. THEY STATED THAT THE MECHS HAD CLRED THE WRITTEN DISCREPANCY WITH CORRECTIVE ACTION. HOWEVER; UPON ARR AT THE ACFT; WE NOTED THAT NOTHING HAD ACTUALLY BEEN DONE TO THE ACFT TO CORRECT THE INITIAL PROB AND NO CORRECTIVE ACTION HAD BEEN ENTERED IN THE LOGBOOK. NO COMPONENTS HAD BEEN CHANGED; NOTHING HAD BEEN CHARGED; SVCED OR ADJUSTED AND NOT EVEN AN ENG HAD BEEN STARTED. I CALLED THE SYS OPS OFFICER AND RELAYED MY CONCERNS. THE FLT PLAN DEST HAD BEEN CHANGED TO ZZZ1 INSTEAD OF ZZZ2. SINCE THIS WOULD REQUIRE AN OVERWT LNDG; WE WERE DIRECTED TO MAINTAIN A LOWER ALT IN ORDER TO INCREASE THE ENRTE FUEL BURN BY AN ADDITIONAL 50%. THIS ADDITIONAL WASTE/BURN OF FUEL WOULD ALLOW US TO LAND AT MAX LNDG WT AFTER COMPLETING A NON-PRECISION APCH IF AVAILABLE OR USE A PRECISION APCH WITH A 20 KT XWIND. WE BLOCKED THE SECOND TIME AND STAYED UNTIL PUSHBACK. AFTER THE SECOND ENG START WE ACTIVATED THE HYDS AND FLT CTLS; LOWERED THE FLAPS AND PERFORMED THE TEST AGAIN; PRIOR TO THE MECH BEING RELEASED FROM THE HEADSET. AGAIN AS IN ANY AND ALL CASES WITH THIS CONDITION; THERE WAS NO FLUCTUATION IN THE SYS PRESSURE GAUGE; AS REQUIRED; WHEN THE RUDDER PRETKOF CHK WAS PERFORMED. WE TAXIED BACK INTO PARKING FOR OUR SECOND BLOCK TURN BACK. WE REMAINED IN CONTACT WITH CREW SCHEDULING; VIA CONTINGENCY AND MAINT. AGAIN THE MECH TOLD US THAT THE PROB HAD BEEN FIXED. I INQUIRED AS TO WHAT ACTION WAS TAKEN; HE RESPONDED THAT HE COULD NOT DUPLICATE THE PROB. WE QUIZZED THE MECH VERY INTENTLY; AND DETERMINED THAT HE WAS INCORRECTLY PERFORMING THE TEST; IN OTHER WORDS; HE WAS NOT FOLLOWING THE AOM PROC REQUIRING THE CAPT TO FIRMLY HOLD THE STEERING WHEEL WHEN PERFORMING THE TEST. PER THE SYS MANUAL; IF THE TEST IS PERFORMED WITHOUT HOLDING THE STEERING WHEEL; THE PRESSURE FLUCTUATION INDICATED IS THAT OF THE NOSEWHEEL STEERING AND NOT THAT OF THE RUDDER. HE ASSURED US THAT HE WAS PERFORMING THE TEST AS PER THE AOM. WE INFORMED THE MECH THAT WE WOULD TAKE HIM AT HIS WORD; BUT THAT A RETURN TO THE BLOCKS AGAIN WOULD MAKE THE THIRD REPETITIVE WRITE-UP ON THE SAME MAINT ISSUE. IN ORDER TO PROVIDE ILLUSTRATION AND CLARIFICATION FOR ALL INVOLVED; WENOTED THAT WE WOULD DEPART IF IT WOULD TEST FOR US WITH HIS SUPERVISION 'AGAIN' IN THE BLOCKS. WE PREPARED THE ACFT FOR DEP A THIRD TIME WHILE THE MECH AGAIN CLRED THE WRITE-UP; NOTING NO CORRECTIVE ACTION BUT ONLY 'OPS CHKS GOOD' WITH HIS SIGNATURE. HE REPEATED THE SAME ACTION AND STATED THAT HE COULD NOT DUPLICATE THE PROB. ON THIS THIRD ATTEMPT; WHILE STILL IN THE BLOCKS WE STARTED ENG #3 WITH THE FLAPS AT 18 DEGS FOR TKOF. AGAIN THE ACFT INDICATED NORMAL HYDS WITH THE EXCEPTION OF THE RUDDER DROP/RISE INDICATION THAT IS REQUIRED ON THE BEFORE TKOF CHKLIST. THE FAILURE OF THE SYS TO PASS THIS CHK WAS ALSO DEMONSTRATED FOR AN ADDITIONAL TIME TO ZZZ LINE MECH. WE ENTERED THIS SAME DISCREPANCY IN THE ACFT'S LOGBOOK FOR A THIRD TIME. IT CONCERNED US ALL THAT THIS WAS THE THIRD TIME THAT WE HAD DEMONSTRATED THE ACFT'S FAILURE TO PASS A REQUIRED PRETKOF CHK AND YET EACH TIME THE MECH WAS WILLING TO SIGN THE ITEM OFF AFTER PERFORMING NO CORRECTIVE ACTION. OF ADDITIONAL CONCERN; AND PERHAPS WORTHY OF NOTING IS THAT THE ACFT CURRENTLY HAS SEVERAL OPEN ITEMS INVOLVING INTERIM HYD FLEX LINE INSTALLATIONS IN RESERVOIR RETURNS. WHILE IT IS NOT MY INTENT TO PROVIDE TROUBLESHOOTING ADVICE; OUR CREW WAS CONCERNED THAT THERE WAS LITTLE IF ANY SUPPORT FROM MAINT ON RESOLVING AN ISSUE BEFORE IT BECAME NECESSARY TO DEMONSTRATE AND DOCUMENT IN THE ACFT LOGBOOK THE SAME FLT CTL DISCREPANCY 3 TIMES IN 1 EVENING WITHOUT OBSERVING ANY EFFORT TO REPAIR OR ACCOMPLISH CORRECTIVE ACTION. IT IS FOR THIS REASON; COUPLED WITH THE RECENT SCRUTINY AFFORDED ACFT LOGBOOKS AND THE CREW'S RESPONSIBILITY FOR MAINTAINING AND VERIFYING THE ACCURACY OF SUCH DOCUMENTS; THAT I HAVE SUBMITTED THIS RPT.