Narrative:

I had an A321 aircraft inbound for an additional center tank-1 (act-1) failed to transfer fuel write-up. So; I called maintenance control; we then agreed to MEL the discrepancy. The MEL required me to deactivate the act transfer valve in the 'closed' position. I followed the aircraft maintenance manual (amm) 28-28-00-040-a. After the aircraft left; got a call from maintenance control saying the pilot reported that he was getting fuel from act-1 tank. After reading the amm reference over again and talking to a few fellow mechanics; I realized I may have inadvertently locked the valve in the 'open' position. Causes were due to miss-reading the transfer valve indicator; poor lighting; incorrect ladder that gave me an awkward angle for viewing the valve and indicator. Pilot reported [discrepancy] due to fuel being transferred from the act-1. The incident was already corrected once I was notified about it. Notified maintenance control duty manager about this event. [Recommend] to have a second mechanic witness the valve position.

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Original NASA ASRS Text

Title: A Line; Lead Aircraft Maintenance Technician (AMT) and a Maintenance Controller describe their involvement with an MEL deferral of an Additional Center Tank (ACT) Fuel Transfer Valve that was incorrectly moved to the 'open' position instead of the 'closed' position; on an A321 aircraft. Lead Technician also notes the reference pictures in the Aircraft Maintenance Manual (AMM) for the Transfer Valve Motor actuator position indicators are confusing.

Narrative: I had an A321 aircraft inbound for an Additional Center Tank-1 (ACT-1) failed to transfer fuel write-up. So; I called Maintenance Control; we then agreed to MEL the discrepancy. The MEL required me to deactivate the ACT Transfer Valve in the 'closed' position. I followed the Aircraft Maintenance Manual (AMM) 28-28-00-040-A. After the aircraft left; got a call from Maintenance Control saying the pilot reported that he was getting fuel from ACT-1 tank. After reading the AMM reference over again and talking to a few fellow mechanics; I realized I may have inadvertently locked the valve in the 'open' position. Causes were due to miss-reading the Transfer Valve Indicator; poor lighting; incorrect ladder that gave me an awkward angle for viewing the valve and indicator. Pilot reported [discrepancy] due to fuel being transferred from the ACT-1. The incident was already corrected once I was notified about it. Notified Maintenance Control Duty Manager about this event. [Recommend] to have a second mechanic witness the valve position.

Data retrieved from NASA's ASRS site 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.