Narrative:

On nov/xx/94 boeing 727 tail # X departed tpa for mexico city. After departure there was a loss of 'a' system hydraulic fluid. The crew made an air turn back and reported in the logbook that there was loss of 'a' system hydraulic fluid and otb. Trailing edge flaps did not extend with alternate system. After servicing the 'a' system and pressure checking the related components I found the hydraulic leak at #3 leading edge flap actuator. I reviewed the maintenance manual for removal and installation of the actuator. I removed and replaced the actuator per the maintenance manual. A .028 inch or less gap was the required clearance between the actuator end caps and the wing web where the actuator is mounted. When I installed the aft end of the actuator there was very little clearance. I felt that the trunion caps had bottomed out and there was not enough gap to require shims. The installation was inspected by 1 of our line inspectors. I made an operations check and leak check. This was also checked by the inspector. We ran the engines, checked 'a' system quantity and pressure. I then replaced the alternate otb trailing edge flap drive motor. All checked good. At XX00 on nov/xx/94 the aircraft was released for a flight to clt. It flew 6 scheduled flts on nov/xx/94 and the next day, it flew from phl-pit-clt-pit. After landing at pit the 'a system quantity was lost after flap retraction. The leak was again at #3 leading edge flap actuator. The aircraft was taken to the hangar by mechanics and the FAA. When removing the actuator they reported a .080 inch clearance between the actuator trunion caps and the wing web. The FAA thinks this could cause the leak and I did not install the actuator in accordance with the maintenance manual. I think there must have been a small burr or some paint in the new trunion caps preventing them to seat properly. I have not talked with the FAA yet. I don't know exactly where the leak was found, but I do not think the missing shims or the .080 gap between the trunion caps and the web could have caused a leak. Supplemental information from acn 290160: unit was installed in accordance with maintenance manual 27-2 dg 401-403 leak check and operational checks were performed. No leaks were found, operational checks were normal.

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Original NASA ASRS Text

Title: MAINT HANDLING OF LEAKING SLAT.

Narrative: ON NOV/XX/94 BOEING 727 TAIL # X DEPARTED TPA FOR MEXICO CITY. AFTER DEP THERE WAS A LOSS OF 'A' SYS HYD FLUID. THE CREW MADE AN AIR TURN BACK AND RPTED IN THE LOGBOOK THAT THERE WAS LOSS OF 'A' SYS HYD FLUID AND OTB. TRAILING EDGE FLAPS DID NOT EXTEND WITH ALTERNATE SYS. AFTER SVCING THE 'A' SYS AND PRESSURE CHKING THE RELATED COMPONENTS I FOUND THE HYD LEAK AT #3 LEADING EDGE FLAP ACTUATOR. I REVIEWED THE MAINT MANUAL FOR REMOVAL AND INSTALLATION OF THE ACTUATOR. I REMOVED AND REPLACED THE ACTUATOR PER THE MAINT MANUAL. A .028 INCH OR LESS GAP WAS THE REQUIRED CLRNC BTWN THE ACTUATOR END CAPS AND THE WING WEB WHERE THE ACTUATOR IS MOUNTED. WHEN I INSTALLED THE AFT END OF THE ACTUATOR THERE WAS VERY LITTLE CLRNC. I FELT THAT THE TRUNION CAPS HAD BOTTOMED OUT AND THERE WAS NOT ENOUGH GAP TO REQUIRE SHIMS. THE INSTALLATION WAS INSPECTED BY 1 OF OUR LINE INSPECTORS. I MADE AN OPS CHK AND LEAK CHK. THIS WAS ALSO CHKED BY THE INSPECTOR. WE RAN THE ENGS, CHKED 'A' SYS QUANTITY AND PRESSURE. I THEN REPLACED THE ALTERNATE OTB TRAILING EDGE FLAP DRIVE MOTOR. ALL CHKED GOOD. AT XX00 ON NOV/XX/94 THE ACFT WAS RELEASED FOR A FLT TO CLT. IT FLEW 6 SCHEDULED FLTS ON NOV/XX/94 AND THE NEXT DAY, IT FLEW FROM PHL-PIT-CLT-PIT. AFTER LNDG AT PIT THE 'A SYS QUANTITY WAS LOST AFTER FLAP RETRACTION. THE LEAK WAS AGAIN AT #3 LEADING EDGE FLAP ACTUATOR. THE ACFT WAS TAKEN TO THE HANGAR BY MECHS AND THE FAA. WHEN REMOVING THE ACTUATOR THEY RPTED A .080 INCH CLRNC BTWN THE ACTUATOR TRUNION CAPS AND THE WING WEB. THE FAA THINKS THIS COULD CAUSE THE LEAK AND I DID NOT INSTALL THE ACTUATOR IN ACCORDANCE WITH THE MAINT MANUAL. I THINK THERE MUST HAVE BEEN A SMALL BURR OR SOME PAINT IN THE NEW TRUNION CAPS PREVENTING THEM TO SEAT PROPERLY. I HAVE NOT TALKED WITH THE FAA YET. I DON'T KNOW EXACTLY WHERE THE LEAK WAS FOUND, BUT I DO NOT THINK THE MISSING SHIMS OR THE .080 GAP BTWN THE TRUNION CAPS AND THE WEB COULD HAVE CAUSED A LEAK. SUPPLEMENTAL INFO FROM ACN 290160: UNIT WAS INSTALLED IN ACCORDANCE WITH MAINT MANUAL 27-2 DG 401-403 LEAK CHK AND OPERATIONAL CHKS WERE PERFORMED. NO LEAKS WERE FOUND, OPERATIONAL CHKS WERE NORMAL.

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.