Narrative:

I was given aircraft to remove and replace a borrowed nose landing gear down-lock actuator. I printed a copy of the maintenance manual reference and proceeded to aircraft. I removed and replaced the nose landing gear down-lock actuator as per the maintenance manual reference task. I then operations and leak checked it and found to pass as per maintenance manual. However I did not know it was an rii item. Because in the past rii part I changed the rii was outlined or shown in the task paperwork or an inspector was already present to perform the signoff; so the nose landing gear down-lock actuator failed to receive an rii this time. I now know where to look up what items require rii signoffs in the maintenance manual paperwork. In reference to the above during a fact finding review; I was informed that I misunderstood the maintenance manual installation test for the lock actuator task. In the maintenance manual it gives 2 methods to do the test check. The first one is to use jacks and swing the gear if you have them. The second is to do a test on the ground. I chose to do the one on the ground. Our maintenance manual led me to think I could choose which method to use. The sentence reads 'choose one method to test the lock actuator.' but in the fact finding it was shown to me I should have chosen the first test and swung the gear because we have jacks. It was a heavy workload night. I was given 2 aircraft and was asked to help work on 2 others; one with a bleed trip that needed a high power run and the other was a service check. We had 23 ron (routine overnights) that night. So since I thought I could choose which down-lock test to do I chose the ground test so I could help with the other aircraft. When I performed the ground test with a fellow mechanic I saw the nose landing gear down-lock actuator move according to the test outline and the mechanic in the cockpit was able to hear and feel the movements through the floor and with no hydraulic leaks; it appeared to operations check good. Callback conversation with reporter revealed the following information: reporter stated this was an air turnback situation due to the failure of an internal o-ring that prevented the nose landing down-lock actuator from releasing and allowing the nose landing gear to retract. Reporter also stated the MM reference allowing him to choose between doing a gear swing or a ground test was confusing. So; he has submitted a request to change the MM language clarifying the use of aircraft jacks.

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Original NASA ASRS Text

Title: A B737-700 ACFT NOSE LNDG GEAR DOWN-LOCK ACTUATOR REPLACED. MAINT CHOSE A GROUND TEST THAT DOES NOT REQUIRE A GEAR SWING. DOWN-LOCK ACTUATOR FAILED TO RELEASE INTERNALLY AND NOSE LNDG GEAR WOULD NOT RETRACT AFTER TAKE-OFF.

Narrative: I WAS GIVEN ACFT TO REMOVE AND REPLACE A BORROWED NOSE LNDG GEAR DOWN-LOCK ACTUATOR. I PRINTED A COPY OF THE MAINT MANUAL REF AND PROCEEDED TO ACFT. I REMOVED AND REPLACED THE NOSE LNDG GEAR DOWN-LOCK ACTUATOR AS PER THE MAINT MANUAL REF TASK. I THEN OPS AND LEAK CHKED IT AND FOUND TO PASS AS PER MAINT MANUAL. HOWEVER I DID NOT KNOW IT WAS AN RII ITEM. BECAUSE IN THE PAST RII PART I CHANGED THE RII WAS OUTLINED OR SHOWN IN THE TASK PAPERWORK OR AN INSPECTOR WAS ALREADY PRESENT TO PERFORM THE SIGNOFF; SO THE NOSE LNDG GEAR DOWN-LOCK ACTUATOR FAILED TO RECEIVE AN RII THIS TIME. I NOW KNOW WHERE TO LOOK UP WHAT ITEMS REQUIRE RII SIGNOFFS IN THE MAINT MANUAL PAPERWORK. IN REF TO THE ABOVE DURING A FACT FINDING REVIEW; I WAS INFORMED THAT I MISUNDERSTOOD THE MAINT MANUAL INSTALLATION TEST FOR THE LOCK ACTUATOR TASK. IN THE MAINT MANUAL IT GIVES 2 METHODS TO DO THE TEST CHK. THE FIRST ONE IS TO USE JACKS AND SWING THE GEAR IF YOU HAVE THEM. THE SECOND IS TO DO A TEST ON THE GND. I CHOSE TO DO THE ONE ON THE GND. OUR MAINT MANUAL LED ME TO THINK I COULD CHOOSE WHICH METHOD TO USE. THE SENTENCE READS 'CHOOSE ONE METHOD TO TEST THE LOCK ACTUATOR.' BUT IN THE FACT FINDING IT WAS SHOWN TO ME I SHOULD HAVE CHOSEN THE FIRST TEST AND SWUNG THE GEAR BECAUSE WE HAVE JACKS. IT WAS A HVY WORKLOAD NIGHT. I WAS GIVEN 2 ACFT AND WAS ASKED TO HELP WORK ON 2 OTHERS; ONE WITH A BLEED TRIP THAT NEEDED A HIGH PWR RUN AND THE OTHER WAS A SVC CHK. WE HAD 23 RON (ROUTINE OVERNIGHTS) THAT NIGHT. SO SINCE I THOUGHT I COULD CHOOSE WHICH DOWN-LOCK TEST TO DO I CHOSE THE GND TEST SO I COULD HELP WITH THE OTHER ACFT. WHEN I PERFORMED THE GND TEST WITH A FELLOW MECH I SAW THE NOSE LNDG GEAR DOWN-LOCK ACTUATOR MOVE ACCORDING TO THE TEST OUTLINE AND THE MECH IN THE COCKPIT WAS ABLE TO HEAR AND FEEL THE MOVEMENTS THROUGH THE FLOOR AND WITH NO HYD LEAKS; IT APPEARED TO OPS CHK GOOD. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED THIS WAS AN AIR TURNBACK SITUATION DUE TO THE FAILURE OF AN INTERNAL O-RING THAT PREVENTED THE NOSE LNDG DOWN-LOCK ACTUATOR FROM RELEASING AND ALLOWING THE NOSE LNDG GEAR TO RETRACT. REPORTER ALSO STATED THE MM REFERENCE ALLOWING HIM TO CHOOSE BETWEEN DOING A GEAR SWING OR A GROUND TEST WAS CONFUSING. SO; HE HAS SUBMITTED A REQUEST TO CHANGE THE MM LANGUAGE CLARIFYING THE USE OF ACFT JACKS.

Data retrieved from NASA's ASRS site as of January 2009 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.