Narrative:

An ATR-72 was in the hangar and on jacks at the beginning of my shift at xa:30pm. I received my assignment for [another aircraft]; to work a bleed leak; but it was an aircraft on ground (aog) for a tube assembly. Unable to do any work on my assigned aircraft; I moved to aircraft ATR-72. The discrepancy was nose gear strut (nlg) is showing no chrome. The previous shift had decided to do a full service of the nlg strut since the strut was low; but there were no signs of fluid leakage.I received a verbal [shift] turnover that the tool had been installed before I took over. I completed the service per the ATR-72 job card and maintenance manual [chapter] 12-12-32 and checked for leakage of the strut over the next hour. I removed tool XXX; (the wrench part); but was unaware that there were two pieces to the tool. The second piece was left on the schrader valve on the nlg strut and caused the schrader valve to break and sheet metal damage [occurred] behind the nlg strut. The plane returned to the hangar with the same discrepancy. It was then that I discovered the event.this event was caused by my lack of experience on the aircraft and on the task. The tool was already installed and both pieces have the same reference number. I removed the wrench half; but the other part is chrome and threaded like the end of a schrader valve so I thought that it was part of the gear assembly. It was not my intention to deviate from procedures. I had the reference printed out and went step-by-step. When the task said to remove tool XXX; it did not specify that it was two pieces.maintenance manual procedures on this task should be clarified. Training for this task should occur notifying other mechanics who have not serviced an ATR nose strut; that this tool is two pieces and needs to be removed. Paint these tools red and attach a 'remove before flight' tag.

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Original NASA ASRS Text

Title: A Mechanic reported a company ATR-72 returned to the hangar with the same discrepancy of a nose landing gear (NLG)strut showing 'no' chrome; after he completed a previous full service strut procedure. He discovered the NLG schrader valve was broken and that he had removed only one part of a two-piece tool for the strut servicing.

Narrative: An ATR-72 was in the hangar and on jacks at the beginning of my shift at XA:30pm. I received my assignment for [another aircraft]; to work a bleed leak; but it was an aircraft on ground (AOG) for a tube assembly. Unable to do any work on my assigned aircraft; I moved to aircraft ATR-72. The discrepancy was nose gear strut (NLG) is showing no chrome. The previous shift had decided to do a full service of the NLG strut since the strut was low; but there were no signs of fluid leakage.I received a verbal [shift] turnover that the tool had been installed before I took over. I completed the service per the ATR-72 job card and Maintenance manual [Chapter] 12-12-32 and checked for leakage of the strut over the next hour. I removed tool XXX; (the wrench part); but was unaware that there were two pieces to the tool. The second piece was left on the schrader valve on the NLG strut and caused the schrader valve to break and sheet metal damage [occurred] behind the NLG strut. The plane returned to the hangar with the same discrepancy. It was then that I discovered the event.This event was caused by my lack of experience on the aircraft and on the task. The tool was already installed and both pieces have the same reference number. I removed the wrench half; but the other part is chrome and threaded like the end of a schrader valve so I thought that it was part of the gear assembly. It was not my intention to deviate from procedures. I had the reference printed out and went step-by-step. When the task said to remove tool XXX; it did not specify that it was two pieces.Maintenance manual procedures on this task should be clarified. Training for this task should occur notifying other mechanics who have not serviced an ATR nose strut; that this tool is two pieces and needs to be removed. Paint these tools red and attach a 'remove before flight' tag.

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.