Narrative:

My crew and I were tasked to remove and replace (right/right) the upper and lower nose gear barrel assembly on a cessna C-750 aircraft. I; lead mechanic X; got the maintenance manual (MM) references pertaining to this task to include; the aircraft maintenance manual (amm); component maintenance manual (cmm) and the illustrated parts catalog (ipc). The removal and replacement went smooth and uneventful.we then performed a gear swing; first; a slow cycle to ensure proper operation and then full pressure swing. Mechanic Y was at the hydraulic mule [hydraulic pressure source]; mechanic Z in the cockpit and I; mechanic X was at the nose gear to check for unobstructed movement. The gear went up and locked; then down and locked and I was told all indications were normal [by mechanic Z]. I also requested a maintenance taxi on the post maintenance engine runs to ensure nose wheel steering under aircraft power. This check was good also. Three days later; I was informed that aircraft had to return to ZZZ due to a gear unlocked indication. It was then discovered by me that the nose gear uplock roller was inadvertently installed incorrectly.[I suggest] multiple personnel be used to observe operational checks; rotating duties or position. Or the individual with the most knowledge of the system should observe the indications and operations.

Related reports:

Google
 

Original NASA ASRS Text

Title: Two Mechanics and one Lead Mechanic report a Cessna C750 Citation returned to field after the nose landing gear did not get an 'Up' and 'Locked' indication after takeoff. Nose gear upper and lower barrel assembly had just been replaced. Nose gear uplock roller was found installed incorrectly.

Narrative: My crew and I were tasked to Remove and Replace (R/R) the upper and lower nose gear barrel assembly on a Cessna C-750 aircraft. I; Lead Mechanic X; got the Maintenance Manual (MM) references pertaining to this task to include; the Aircraft Maintenance Manual (AMM); Component Maintenance Manual (CMM) and the Illustrated Parts Catalog (IPC). The removal and replacement went smooth and uneventful.We then performed a gear swing; first; a slow cycle to ensure proper operation and then full pressure swing. Mechanic Y was at the hydraulic mule [hydraulic pressure source]; Mechanic Z in the cockpit and I; Mechanic X was at the nose gear to check for unobstructed movement. The gear went up and locked; then down and locked and I was told all indications were normal [by Mechanic Z]. I also requested a Maintenance Taxi on the Post Maintenance Engine Runs to ensure nose wheel steering under aircraft power. This Check was good also. Three days later; I was informed that aircraft had to return to ZZZ due to a Gear Unlocked Indication. It was then discovered by me that the nose gear uplock roller was inadvertently installed incorrectly.[I suggest] multiple personnel be used to observe Operational Checks; rotating duties or position. Or the individual with the most knowledge of the system should observe the indications and operations.

Data retrieved from NASA's ASRS site as of April 2012 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.