Narrative:

Was assigned to perform the required through-flight pre-departure inspection (walk-around) on an large transport. Upon reaching the right main gear wheel well, it was noticed that all areas of the wheel well were coated with hydraulic fluid (skydrol B-4), as well as an area of the lower wing surface within 4' of the main gear. After pressurizing both hydraulic systems (a and B), a small leak was evident at the 'B-nuts' on the main gear inboard door actuator selector valve above the ground release handle (for gear door). The aircraft was nearing scheduled departure time, so the aircraft was secured and routine boarding and ramp service continued. At approximately 5 mins prior to departure, reporting mechanic went to the right wheel well area again, and being unsure of the aforementioned corrective action as solving the problem, removed a lower wing panel just outboard of the right gear up/down actuator. With hydraulic systems a and B pressurized, a small amount of fluid was noted to be leaking from the main gear pressure reducer valve (down pressure line to main gear actuator). At the time of discovery, it was this mechanic's option that the leaking valve would leak only when the gear selector valve handle (in cockpit) was in the down position and not in the up or off position as in cruise flight confign, therefore, the aircraft could remain in service until more time was available for part replacement. After the aircraft departed, it was determined that should a total failure of this valve occur (when gear selected to 'down' position) that the right main gear would malfunction in the extend mode, and result in hydraulic fluid loss to an extent to seriously hamper normal operation of all landing gear systems. It is this mechanic's opinion that this oversight in performance was in part due to the pressure placed upon line maintenance personnel, by shift supervision, to 'turn' the aircraft with a minimum of down time. This is most easily accomplished by informing the flight crew of very limited information concerning the situation, and the only if 'noticed' by the flight crew on their walk-around inspection. I believe this pressure prevents maintenance personnel from taking the time to fully research any problems, and do whatever action is required.

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Original NASA ASRS Text

Title: MECHANIC ALLOWS AN ACR LGT TO PROCEED ON A SCHEDULED FLT WITH AN OBVIOUS HYDRAULIC LEAK.

Narrative: WAS ASSIGNED TO PERFORM THE REQUIRED THROUGH-FLT PRE-DEP INSPECTION (WALK-AROUND) ON AN LGT. UPON REACHING THE RIGHT MAIN GEAR WHEEL WELL, IT WAS NOTICED THAT ALL AREAS OF THE WHEEL WELL WERE COATED WITH HYDRAULIC FLUID (SKYDROL B-4), AS WELL AS AN AREA OF THE LOWER WING SURFACE WITHIN 4' OF THE MAIN GEAR. AFTER PRESSURIZING BOTH HYDRAULIC SYSTEMS (A AND B), A SMALL LEAK WAS EVIDENT AT THE 'B-NUTS' ON THE MAIN GEAR INBOARD DOOR ACTUATOR SELECTOR VALVE ABOVE THE GND RELEASE HANDLE (FOR GEAR DOOR). THE ACFT WAS NEARING SCHEDULED DEP TIME, SO THE ACFT WAS SECURED AND ROUTINE BOARDING AND RAMP SERVICE CONTINUED. AT APPROX 5 MINS PRIOR TO DEP, REPORTING MECHANIC WENT TO THE RIGHT WHEEL WELL AREA AGAIN, AND BEING UNSURE OF THE AFOREMENTIONED CORRECTIVE ACTION AS SOLVING THE PROBLEM, REMOVED A LOWER WING PANEL JUST OUTBOARD OF THE RIGHT GEAR UP/DOWN ACTUATOR. WITH HYDRAULIC SYSTEMS A AND B PRESSURIZED, A SMALL AMOUNT OF FLUID WAS NOTED TO BE LEAKING FROM THE MAIN GEAR PRESSURE REDUCER VALVE (DOWN PRESSURE LINE TO MAIN GEAR ACTUATOR). AT THE TIME OF DISCOVERY, IT WAS THIS MECHANIC'S OPTION THAT THE LEAKING VALVE WOULD LEAK ONLY WHEN THE GEAR SELECTOR VALVE HANDLE (IN COCKPIT) WAS IN THE DOWN POSITION AND NOT IN THE UP OR OFF POSITION AS IN CRUISE FLT CONFIGN, THEREFORE, THE ACFT COULD REMAIN IN SERVICE UNTIL MORE TIME WAS AVAILABLE FOR PART REPLACEMENT. AFTER THE ACFT DEPARTED, IT WAS DETERMINED THAT SHOULD A TOTAL FAILURE OF THIS VALVE OCCUR (WHEN GEAR SELECTED TO 'DOWN' POSITION) THAT THE RIGHT MAIN GEAR WOULD MALFUNCTION IN THE EXTEND MODE, AND RESULT IN HYDRAULIC FLUID LOSS TO AN EXTENT TO SERIOUSLY HAMPER NORMAL OPERATION OF ALL LNDG GEAR SYSTEMS. IT IS THIS MECHANIC'S OPINION THAT THIS OVERSIGHT IN PERFORMANCE WAS IN PART DUE TO THE PRESSURE PLACED UPON LINE MAINT PERSONNEL, BY SHIFT SUPERVISION, TO 'TURN' THE ACFT WITH A MINIMUM OF DOWN TIME. THIS IS MOST EASILY ACCOMPLISHED BY INFORMING THE FLT CREW OF VERY LIMITED INFO CONCERNING THE SITUATION, AND THE ONLY IF 'NOTICED' BY THE FLT CREW ON THEIR WALK-AROUND INSPECTION. I BELIEVE THIS PRESSURE PREVENTS MAINT PERSONNEL FROM TAKING THE TIME TO FULLY RESEARCH ANY PROBLEMS, AND DO WHATEVER ACTION IS REQUIRED.

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.