Narrative:

Return to field due to main landing gear proximity sensor targets installed backwards. 3 mechanics changed the l-hand main landing gear torque links on aircraft X. One of the mechanics swapped over the proximity sensor targets; from the removed upper torque link to the serviceable torque link. In doing so; he installed them backwards. With the shock strut compressed; there was no difference of results in the adjustment test of the sensor. Aircraft was released for revenue flight. Aircraft took off and the flight crew were unable to retract the landing gear. Aircraft returned to field with no further incidents (and) returned to hangar and the targets were reinstalled correctly with a successful landing gear retraction test. Aircraft manual states to install target with a note: make sure that you install the target in its correct position. When the landing gear is extended; the sensor will be above the longer notch aft of the sensor face. We think it should read: when the strut or sliding member is extended. If the landing gear is extended and on the ground; the strut or sliding member is compressed and your sensor target is in a different position. Corrective action: the subject of attention to detail and to ask questions if they are not sure about a task has been addressed with the involved mechanics. Also; the mechanics are submitting a manual change request to change landing gear extension to strut or sliding member extension also; possibly having the task call for gear swings.

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Original NASA ASRS Text

Title: A CRJ 700 ACFT RETURNED TO FIELD DUE TO THE FACT THAT THE LH MAIN LANDING GEAR WOULD NOT RETRACT. PROXIMITY SENSOR TARGETS INSTALLED BACKWARDS.

Narrative: RETURN TO FIELD DUE TO MAIN LNDG GEAR PROX SENSOR TARGETS INSTALLED BACKWARDS. 3 MECHS CHANGED THE L-HAND MAIN LNDG GEAR TORQUE LINKS ON ACFT X. ONE OF THE MECHS SWAPPED OVER THE PROX SENSOR TARGETS; FROM THE REMOVED UPPER TORQUE LINK TO THE SERVICEABLE TORQUE LINK. IN DOING SO; HE INSTALLED THEM BACKWARDS. WITH THE SHOCK STRUT COMPRESSED; THERE WAS NO DIFFERENCE OF RESULTS IN THE ADJUSTMENT TEST OF THE SENSOR. ACFT WAS RELEASED FOR REVENUE FLT. ACFT TOOK OFF AND THE FLT CREW WERE UNABLE TO RETRACT THE LNDG GEAR. ACFT RETURNED TO FIELD WITH NO FURTHER INCIDENTS (AND) RETURNED TO HANGAR AND THE TARGETS WERE REINSTALLED CORRECTLY WITH A SUCCESSFUL LNDG GEAR RETRACTION TEST. ACFT MANUAL STATES TO INSTALL TARGET WITH A NOTE: MAKE SURE THAT YOU INSTALL THE TARGET IN ITS CORRECT POS. WHEN THE LNDG GEAR IS EXTENDED; THE SENSOR WILL BE ABOVE THE LONGER NOTCH AFT OF THE SENSOR FACE. WE THINK IT SHOULD READ: WHEN THE STRUT OR SLIDING MEMBER IS EXTENDED. IF THE LNDG GEAR IS EXTENDED AND ON THE GND; THE STRUT OR SLIDING MEMBER IS COMPRESSED AND YOUR SENSOR TARGET IS IN A DIFFERENT POS. CORRECTIVE ACTION: THE SUBJECT OF ATTN TO DETAIL AND TO ASK QUESTIONS IF THEY ARE NOT SURE ABOUT A TASK HAS BEEN ADDRESSED WITH THE INVOLVED MECHS. ALSO; THE MECHS ARE SUBMITTING A MANUAL CHANGE REQUEST TO CHANGE LNDG GEAR EXTENSION TO STRUT OR SLIDING MEMBER EXTENSION ALSO; POSSIBLY HAVING THE TASK CALL FOR GEAR SWINGS.

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.