Narrative:

On nov/xa/00 aircraft xyz was in ZZZ for an alternate brake bleed problem. Problem was corrected and signed off in logbook. A new item was generated for 'parking brake on' message on EFIS. Myself and another mechanic found that parking brake cable rotates a quadrant which makes or breaks a micro-switch to turn on and off the message on EFIS. This cable quadrant mechanism was also not rigged properly according to maintenance manual. We proceeded to adjust the parking brake cable per the maintenance manual. Once complete, we accomplished all required tests that manual called out. Hydraulic xfer system, cvr operations, parking brake valve and takeoff warning checks were accomplished. Aircraft then was taken to gate for revenue service. On takeoff roll, pilot noticed aircraft slow to accelerate and aborted takeoff. #3 tire was deflated and upon inspection of brake system we found #3 and #4 brake assembly not releasing. Further investigation revealed that lower shuttle valve quick disconnects were not connected on #3 and #4 brake assembly. Connected lines and replaced both wheel assembly and brake system operated properly. I feel that possibly these quick disconnects need some safety mechanism to prevent any loosening or backing off of hydraulic lines. In addition, other aircraft have had similar brake problems and quick disconnects were found not fully seated against itself.

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Original NASA ASRS Text

Title: A FOKKER 100 ABORTED TKOF DUE TO SLOW TO ACCELERATE. FOUND #3 AND #4 BRAKES NOT RELEASING DUE TO ALTERNATE HYD LINES QUICK DISCONNECT FITTINGS NOT CONNECTED.

Narrative: ON NOV/XA/00 ACFT XYZ WAS IN ZZZ FOR AN ALTERNATE BRAKE BLEED PROB. PROB WAS CORRECTED AND SIGNED OFF IN LOGBOOK. A NEW ITEM WAS GENERATED FOR 'PARKING BRAKE ON' MESSAGE ON EFIS. MYSELF AND ANOTHER MECH FOUND THAT PARKING BRAKE CABLE ROTATES A QUADRANT WHICH MAKES OR BREAKS A MICRO-SWITCH TO TURN ON AND OFF THE MESSAGE ON EFIS. THIS CABLE QUADRANT MECHANISM WAS ALSO NOT RIGGED PROPERLY ACCORDING TO MAINT MANUAL. WE PROCEEDED TO ADJUST THE PARKING BRAKE CABLE PER THE MAINT MANUAL. ONCE COMPLETE, WE ACCOMPLISHED ALL REQUIRED TESTS THAT MANUAL CALLED OUT. HYD XFER SYS, CVR OPS, PARKING BRAKE VALVE AND TKOF WARNING CHKS WERE ACCOMPLISHED. ACFT THEN WAS TAKEN TO GATE FOR REVENUE SVC. ON TKOF ROLL, PLT NOTICED ACFT SLOW TO ACCELERATE AND ABORTED TKOF. #3 TIRE WAS DEFLATED AND UPON INSPECTION OF BRAKE SYS WE FOUND #3 AND #4 BRAKE ASSEMBLY NOT RELEASING. FURTHER INVESTIGATION REVEALED THAT LOWER SHUTTLE VALVE QUICK DISCONNECTS WERE NOT CONNECTED ON #3 AND #4 BRAKE ASSEMBLY. CONNECTED LINES AND REPLACED BOTH WHEEL ASSEMBLY AND BRAKE SYS OPERATED PROPERLY. I FEEL THAT POSSIBLY THESE QUICK DISCONNECTS NEED SOME SAFETY MECHANISM TO PREVENT ANY LOOSENING OR BACKING OFF OF HYD LINES. IN ADDITION, OTHER ACFT HAVE HAD SIMILAR BRAKE PROBS AND QUICK DISCONNECTS WERE FOUND NOT FULLY SEATED AGAINST ITSELF.

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.