Technicians reported installing a nose landing gear torque link upside down during maintenance. The flight crew conducting the ferry flight reported the landing gear failed to retract after take off and returned to the departure airport for maintenance.
Synopsis
Technicians reported installing a nose landing gear torque link upside down during maintenance. The flight crew conducting the ferry flight reported the landing gear failed to retract after take off and returned to the departure airport for maintenance.
Narrative
I was installing a torque link with another mechanic. I found out that night that I mistakenly installed the torque link upside down causing the gear to fail to retract on takeoff; causing an air return. There was a trend as a result of a nosewheel shimmy including an inspection of the tolerances on the torque links. We found the torque links to have been loose and worn to limits. We opted to change the torque links. Person A was primarily responsible for the lower torque link and I; Person B; was responsible for the upper torque link. I removed the old upper torque link and proceeded to transfer the proximity targets and pin extraction handles over to the new upper torque link. In this process; I attempted to copy the old torque link and compare them to the image in the Illustrated Parts Catalog and Aircraft Maintenance manual. In doing so; I misinterpreted the photo trying to orient the upper torque link in the same way as the photo. Judging by the ridges in the technical drawing of the torque link on the Aircraft Maintenance manual reference; I mistakenly interpreted it as it going the way I installed it. I later found that to be incorrect and upside down after hearing about the air return. Person A replaced the lower torque arm pin and torque link with no issues and assisted in the installation of the spring and pin of the upper torque link. Supervisor notified after shift brief the following night that my aircraft had an air return as a result of the gear not retracting. I find the cause of this issue to be my first time changing a torque link and not knowing the proper orientation and the manual failing to give any indication of the proper orientation of the torque link. There are no markings on the torque link; or mention of how it is to be oriented besides an oddly angled technical drawing of the torque links in the reference. Add warnings to manual to include a description of the proper orientation of the torque link for install. Add markings to torque links indicating which way is up.
Second reporter narrative
Aircraft X had a WOW (Weight on Wheels) input caution after takeoff and no gear retract. Air return to ZZZ. Both Torque links had been changed on overnight hanger stay for a nose wheel shimmy trend. Both myself and Person B worked the trend. I had changed the lower torque link while Person B changed the upper torque link. Lower torque link was changed ZZZ1 CRJ 900 Aircraft Maintenance manual XX-XX-XX; And upper was changed ZZZ1 CRJ 900 Aircraft Maintenance manual XX-XX-XY. I finished the lower first while Person B was still transferring over the targets and the release handles to the new upper torque link. I Assisted Person B by looking up parts for the items to be transferred and then assisted him in pinning the upper torque link. After air return upper torque links found to be installed upside down. Notified by Supervisor when arriving for shift. The manual does not provide a warning of orientation of torque link can result in gear wow input cautions. Also I did not see how the original upper was originally position as i was away gathering tooling to remove nose tires. It has also been at least one year since my last time changing torque links. Label torque links this side up for correct orientation; add Warning to manual about possible gear sensor malfunction if not orientated correctly. Add better picture to Aircraft Maintenance manual procedure to show difference in proper and in proper orientation.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.