Narrative:

On jul/xa/08 I was assigned to aircraft X. In ZZZ maintenance hangar; one of the tasks that needed to be performed for that night on the aircraft was removing and replacing the nose landing gear steering harness. I chose to do that task since I have never done it before. After ordering the part and getting the required tools and amm; I started the task. While removing the steering harness; I removed a bolt on the bracket for the nose landing gear steering harness to gain access to a clamp to remove it. After removing the old steering harness; I started to install the new one in accordance with the amm. When I got to the step to install one of the cannon plugs; I had a very difficult time getting it on. When I got it on finally it didn't look right to me. I asked a fellow mechanic what he thought; and he said that I would have to reposition the cannon plug. So I re-clocked the cannon plug and moved on to the next step. I finished the task and performed the operations test. Operations test was good; so I signed the task off. The next day that I came to work I was told that the swing shift mechanics were getting ready to taxi the plane to the gate and they got a nosewheel steering caution message. My lead told me that I had installed the cannon plug in wrong and left the hardware off of the bracket. He told me that I was on aircraft X to fix it. After installing a new nosewheel steering harness on jul/xb/08 we were performing the operations function test and the nosewheel steering would not come on and we were still getting the caution message. After further investigation; we found that the reason why we were getting the caution message was due to a broken wire on the back of the nosewheel steering tiller. I think that the event occurred because I was not paying attention to detail. After being assigned to aircraft X the next night; I could see where things went wrong. If I would have stuck to the manual instead of asking another mechanic I would have not made the mistake. Right after the step in the amm that tells you to install the cannon plug there is a warning that tells you that you might have to reposition the cannon plug and to make sure that it is facing forward/aft. I cocked it so that when we did the gear swing the actuator bracket smashed the cannon plug. I forgot to tighten the attaching hardware for the bracket. I think that I was just not paying attention to detail. Read all steps provided in the amm and task cards. Callback conversation with reporter revealed the following information: reporter stated the dhc-8-400 nose wheel steering (NWS) tiller is electrically activated by a switch just forward of the steering tiller on the captain's side. The original problem of NWS caution message; noted by the swing shift taxi crew; was not associated with the harness he had originally replaced. A broken wire on the back side of the tiller was the problem. But; reporter stated the damaged canon plug that was also found damaged; was the one he had not position correctly in a forward-aft orientation that connected to a gear position sensor on the left side of the nlg; looking forward; near the retract actuator. Reporter stated a nose gear swing was required after he replaced the original NWS harness. But; they could not use hydraulics due to other mechanics working on a hydraulic line for one of the main gears. Instead; he and two other mechanics just pushed the nose gear up into the retract position until they heard the uplock engage. Reporter stated none of the mechanics with him; noted any discrepancy; or damaged canon plug at the sensor support bracket.

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Original NASA ASRS Text

Title: AFTER CHANGING A NOSE LANDING GEAR STEERING HARNESS ON A DHC-8-400; A MECHANIC IS INFORMED OF A NOSE STEERING PROBLEM AND DAMAGED CANON PLUG.

Narrative: ON JUL/XA/08 I WAS ASSIGNED TO ACFT X. IN ZZZ MAINT HANGAR; ONE OF THE TASKS THAT NEEDED TO BE PERFORMED FOR THAT NIGHT ON THE ACFT WAS REMOVING AND REPLACING THE NOSE LNDG GEAR STEERING HARNESS. I CHOSE TO DO THAT TASK SINCE I HAVE NEVER DONE IT BEFORE. AFTER ORDERING THE PART AND GETTING THE REQUIRED TOOLS AND AMM; I STARTED THE TASK. WHILE REMOVING THE STEERING HARNESS; I REMOVED A BOLT ON THE BRACKET FOR THE NOSE LNDG GEAR STEERING HARNESS TO GAIN ACCESS TO A CLAMP TO REMOVE IT. AFTER REMOVING THE OLD STEERING HARNESS; I STARTED TO INSTALL THE NEW ONE IN ACCORDANCE WITH THE AMM. WHEN I GOT TO THE STEP TO INSTALL ONE OF THE CANNON PLUGS; I HAD A VERY DIFFICULT TIME GETTING IT ON. WHEN I GOT IT ON FINALLY IT DIDN'T LOOK RIGHT TO ME. I ASKED A FELLOW MECH WHAT HE THOUGHT; AND HE SAID THAT I WOULD HAVE TO REPOSITION THE CANNON PLUG. SO I RE-CLOCKED THE CANNON PLUG AND MOVED ON TO THE NEXT STEP. I FINISHED THE TASK AND PERFORMED THE OPS TEST. OPS TEST WAS GOOD; SO I SIGNED THE TASK OFF. THE NEXT DAY THAT I CAME TO WORK I WAS TOLD THAT THE SWING SHIFT MECHS WERE GETTING READY TO TAXI THE PLANE TO THE GATE AND THEY GOT A NOSEWHEEL STEERING CAUTION MESSAGE. MY LEAD TOLD ME THAT I HAD INSTALLED THE CANNON PLUG IN WRONG AND LEFT THE HARDWARE OFF OF THE BRACKET. HE TOLD ME THAT I WAS ON ACFT X TO FIX IT. AFTER INSTALLING A NEW NOSEWHEEL STEERING HARNESS ON JUL/XB/08 WE WERE PERFORMING THE OPS FUNCTION TEST AND THE NOSEWHEEL STEERING WOULD NOT COME ON AND WE WERE STILL GETTING THE CAUTION MESSAGE. AFTER FURTHER INVESTIGATION; WE FOUND THAT THE REASON WHY WE WERE GETTING THE CAUTION MESSAGE WAS DUE TO A BROKEN WIRE ON THE BACK OF THE NOSEWHEEL STEERING TILLER. I THINK THAT THE EVENT OCCURRED BECAUSE I WAS NOT PAYING ATTN TO DETAIL. AFTER BEING ASSIGNED TO ACFT X THE NEXT NIGHT; I COULD SEE WHERE THINGS WENT WRONG. IF I WOULD HAVE STUCK TO THE MANUAL INSTEAD OF ASKING ANOTHER MECH I WOULD HAVE NOT MADE THE MISTAKE. RIGHT AFTER THE STEP IN THE AMM THAT TELLS YOU TO INSTALL THE CANNON PLUG THERE IS A WARNING THAT TELLS YOU THAT YOU MIGHT HAVE TO REPOSITION THE CANNON PLUG AND TO MAKE SURE THAT IT IS FACING FORWARD/AFT. I COCKED IT SO THAT WHEN WE DID THE GEAR SWING THE ACTUATOR BRACKET SMASHED THE CANNON PLUG. I FORGOT TO TIGHTEN THE ATTACHING HARDWARE FOR THE BRACKET. I THINK THAT I WAS JUST NOT PAYING ATTN TO DETAIL. READ ALL STEPS PROVIDED IN THE AMM AND TASK CARDS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED THE DHC-8-400 NOSE WHEEL STEERING (NWS) TILLER IS ELECTRICALLY ACTIVATED BY A SWITCH JUST FORWARD OF THE STEERING TILLER ON THE CAPTAIN'S SIDE. THE ORIGINAL PROBLEM OF NWS CAUTION MESSAGE; NOTED BY THE SWING SHIFT TAXI CREW; WAS NOT ASSOCIATED WITH THE HARNESS HE HAD ORIGINALLY REPLACED. A BROKEN WIRE ON THE BACK SIDE OF THE TILLER WAS THE PROBLEM. BUT; REPORTER STATED THE DAMAGED CANON PLUG THAT WAS ALSO FOUND DAMAGED; WAS THE ONE HE HAD NOT POSITION CORRECTLY IN A FORWARD-AFT ORIENTATION THAT CONNECTED TO A GEAR POSITION SENSOR ON THE LEFT SIDE OF THE NLG; LOOKING FORWARD; NEAR THE RETRACT ACTUATOR. REPORTER STATED A NOSE GEAR SWING WAS REQUIRED AFTER HE REPLACED THE ORIGINAL NWS HARNESS. BUT; THEY COULD NOT USE HYDRAULICS DUE TO OTHER MECHANICS WORKING ON A HYDRAULIC LINE FOR ONE OF THE MAIN GEARS. INSTEAD; HE AND TWO OTHER MECHANICS JUST PUSHED THE NOSE GEAR UP INTO THE RETRACT POSITION UNTIL THEY HEARD THE UPLOCK ENGAGE. REPORTER STATED NONE OF THE MECHANICS WITH HIM; NOTED ANY DISCREPANCY; OR DAMAGED CANON PLUG AT THE SENSOR SUPPORT BRACKET.

Data retrieved from NASA's ASRS site as of May 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.