Narrative:

An engineering item was called out to replace left wing fuel pressure holding valve and I mistakenly replaced the same valve on the right wing by mistake. We were on feild trip to accomplish a tank entry to complete the job. It was our intent to just open the tank and start venting and return after rest to go in tank. But when we opened the access door to reach valve; discovered that it could be changed easily within five minutes; by reaching in approximately ten inches; no tank entry required so we completed the job. I can't explain why we changed the valve on the wrong side except to say that I asked which side and was told it was the right side; so there was some miscommunication.

Related reports:

Google
 

Original NASA ASRS Text

Title: Three Line Mechanics report about a Maintenance Engineering call out to replace an A320 left wing fuel pressure holding valve on a field trip. Mechanics mistakenly replaced the right wing holding valve instead; with miscommunication cited as a contributor.

Narrative: An Engineering item was called out to replace left wing Fuel Pressure Holding Valve and I mistakenly replaced the same valve on the right wing by mistake. We were on feild trip to accomplish a tank entry to complete the job. It was our intent to just open the tank and start venting and return after rest to go in tank. But when we opened the access door to reach valve; discovered that it could be changed easily within five minutes; by reaching in approximately ten inches; no tank entry required so we completed the job. I can't explain why we changed the valve on the wrong side except to say that I asked which side and was told it was the right side; so there was some miscommunication.

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.