Narrative:

The incorrect fuel control part number was installed on a JT8D engine for the bleed valve affectivity of that engine. I miss-identified a bleed control valve as a start bleed control valve which is only installed on pre-service bulletin engines and requires a -12 fuel control unit. The engine being worked on was a post service bulletin engine with no start bleed control valve and required a -15 fuel control unit. I instructed the mechanics to install the -12 FCU and told them that I verified that it was a pre-service bulletin engine. A contributing factor was my lack of understanding of pre and post service bulletin bleed valve components and identification of same components. The issue was discovered a week later during troubleshooting of a slow to spool discrepancy on the same engine. The FCU was replaced with a -15. I should have verified what a start bleed control valve looked like. I thought I knew but had not worked that system before and in the end; an assumption was made about the part as to shape and mounting location; etc. A power plant matrix with engine serial number and service bulletins accomplished as well as bleed configurations would be helpful. Regardless of a matrix or not the responsibility for correct part installation lies with me.

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Original NASA ASRS Text

Title: Air carrier maintenance personnel installed the incorrect engine fuel control unit for the affectivity due to confusion over configuration and service bulletin status.

Narrative: The incorrect fuel control part number was installed on a JT8D engine for the bleed valve affectivity of that engine. I miss-identified a bleed control valve as a start bleed control valve which is only installed on pre-service bulletin engines and requires a -12 fuel control unit. The engine being worked on was a post service bulletin engine with no start bleed control valve and required a -15 fuel control unit. I instructed the mechanics to install the -12 FCU and told them that I verified that it was a pre-service bulletin engine. A contributing factor was my lack of understanding of pre and post service bulletin bleed valve components and identification of same components. The issue was discovered a week later during troubleshooting of a slow to spool discrepancy on the same engine. The FCU was replaced with a -15. I should have verified what a start bleed control valve looked like. I thought I knew but had not worked that system before and in the end; an assumption was made about the part as to shape and mounting location; etc. A power plant matrix with engine serial number and service bulletins accomplished as well as bleed configurations would be helpful. Regardless of a matrix or not the responsibility for correct part installation lies with me.

Data retrieved from NASA's ASRS site as of July 2013 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.