Narrative:

At approximately XA30 mar/xx/97, I was assigned along with aircraft mechanic ZZZ to remove and replace the right main landing actuator on the aircraft, a DC9-30 flight, due to a leak at the gland nut. Maintenance manual paperwork was obtained and studied. Inspector inspected the new actuator per ipc, part number and effectivity. Mr xyz removed the leaking actuator. After changing the swivel gland, hydraulic line and restrictor over onto the new actuator, I installed the actuator per maintenance manual using the alternate method. I installed the hydraulic lines to the swivel gland without ever removing the lines from the stand off bracket (both supply and return line are secured to the bracket with adel clamps). Both lines use the same size ms fittings. As per maintenance manual, we cycled the actuator 10 times to clear any trapped air and check operation. Mr ZZZ operated the gear handle from the cockpit, gate mechanic xyz gave directions and clearance from the ground using the aircraft maintenance interphone, and I held the actuator cylinder clear of structure at the wheel well. This procedure was observed by inspector. After cycling the actuator, cylinder piston and eye bolt were secured and safetied per maintenance manual and bought off by the inspector. Logbook entry was completed by gate mechanic, mr xyz. As this was an active flight, all work was completed as quickly as possible. Collectively, all 3 mechanics and the inspector never determined that retract cylinder piston travel was opposite landing gear handle position. Per maintenance manual page XXX stated 'check when lever is down, cylinder position is extended,' etc. We never determined that the supply and return lines were reversed. Both mr ZZZ and myself have successfully completed this procedure many times in the past. Flight XXX returned from flight, unable to retract the right main landing gear. The flight was canceled, the aircraft was placed on jacks in the hangar, and a gear swing was attempted. Our error was not correlating the position of the gear lever with the movement of the cylinder. During the time period when the actuator was being cycled, mr. Xyz was called to the adjoining gate to dispatch an outgoing flight. It is possible that this distraction contributed to our missing this crucial step.

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Original NASA ASRS Text

Title: A DC9-30 RETURNED TO THE FIELD DUE TO INABILITY TO RETRACT THE R MAIN LNDG GEAR CAUSED BY CROSSED HYD LINES ON THE RETRACT ACTUATOR.

Narrative: AT APPROX XA30 MAR/XX/97, I WAS ASSIGNED ALONG WITH ACFT MECH ZZZ TO REMOVE AND REPLACE THE R MAIN LNDG ACTUATOR ON THE ACFT, A DC9-30 FLT, DUE TO A LEAK AT THE GLAND NUT. MAINT MANUAL PAPERWORK WAS OBTAINED AND STUDIED. INSPECTOR INSPECTED THE NEW ACTUATOR PER IPC, PART NUMBER AND EFFECTIVITY. MR XYZ REMOVED THE LEAKING ACTUATOR. AFTER CHANGING THE SWIVEL GLAND, HYD LINE AND RESTRICTOR OVER ONTO THE NEW ACTUATOR, I INSTALLED THE ACTUATOR PER MAINT MANUAL USING THE ALTERNATE METHOD. I INSTALLED THE HYD LINES TO THE SWIVEL GLAND WITHOUT EVER REMOVING THE LINES FROM THE STAND OFF BRACKET (BOTH SUPPLY AND RETURN LINE ARE SECURED TO THE BRACKET WITH ADEL CLAMPS). BOTH LINES USE THE SAME SIZE MS FITTINGS. AS PER MAINT MANUAL, WE CYCLED THE ACTUATOR 10 TIMES TO CLR ANY TRAPPED AIR AND CHK OP. MR ZZZ OPERATED THE GEAR HANDLE FROM THE COCKPIT, GATE MECH XYZ GAVE DIRECTIONS AND CLRNC FROM THE GND USING THE ACFT MAINT INTERPHONE, AND I HELD THE ACTUATOR CYLINDER CLR OF STRUCTURE AT THE WHEEL WELL. THIS PROC WAS OBSERVED BY INSPECTOR. AFTER CYCLING THE ACTUATOR, CYLINDER PISTON AND EYE BOLT WERE SECURED AND SAFETIED PER MAINT MANUAL AND BOUGHT OFF BY THE INSPECTOR. LOGBOOK ENTRY WAS COMPLETED BY GATE MECH, MR XYZ. AS THIS WAS AN ACTIVE FLT, ALL WORK WAS COMPLETED AS QUICKLY AS POSSIBLE. COLLECTIVELY, ALL 3 MECHS AND THE INSPECTOR NEVER DETERMINED THAT RETRACT CYLINDER PISTON TRAVEL WAS OPPOSITE LNDG GEAR HANDLE POS. PER MAINT MANUAL PAGE XXX STATED 'CHK WHEN LEVER IS DOWN, CYLINDER POS IS EXTENDED,' ETC. WE NEVER DETERMINED THAT THE SUPPLY AND RETURN LINES WERE REVERSED. BOTH MR ZZZ AND MYSELF HAVE SUCCESSFULLY COMPLETED THIS PROC MANY TIMES IN THE PAST. FLT XXX RETURNED FROM FLT, UNABLE TO RETRACT THE R MAIN LNDG GEAR. THE FLT WAS CANCELED, THE ACFT WAS PLACED ON JACKS IN THE HANGAR, AND A GEAR SWING WAS ATTEMPTED. OUR ERROR WAS NOT CORRELATING THE POS OF THE GEAR LEVER WITH THE MOVEMENT OF THE CYLINDER. DURING THE TIME PERIOD WHEN THE ACTUATOR WAS BEING CYCLED, MR. XYZ WAS CALLED TO THE ADJOINING GATE TO DISPATCH AN OUTGOING FLT. IT IS POSSIBLE THAT THIS DISTR CONTRIBUTED TO OUR MISSING THIS CRUCIAL STEP.

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.