Narrative:

The indicator originally installed on the aircraft; the manufacturer's part number of which crossed over to company part number (ind X) was reported as having a blanking indication for the left main tank on the 'a' channel. When I checked stock on this company part number; it showed zero on hand at the station; and zero system ownership of the part. That company would not own a single unit of a part that was installed on some number of their aircraft made no sense to me; so I referred to the ipc for guidance. The ipc contained a temporary revision; the purpose for which it stated was to clarify the part numbers for airplanes. I found the temporary revision as presented to be somewhat confusing because of the way it was formatted; and determined that the ind Y; which the temporary revision listed; must be the proper part for that aircraft; because there was a substantial number of 'deleted' notations associated with ind X and our supply system showed zero stock and zero ownership of that part number. To check myself; I ran a maintenance operations inquiry on ind Y and that screen showed that part number as covering effectivities. I believed that this was an acceptable xchk that the ind Y was the proper part for this airplane; even as I now acknowledge that I am aware of the caveat on the supply computer screen about not using them as an authoritative source. Reviewed the ipc; realized my reading error. Will have another mechanic check my reasoning process and manual interpretation when working on aircraft in future.

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Original NASA ASRS Text

Title: AN MD80 HAD THE INCORRECT FUEL QUANTITY INDICATOR INSTALLED IN THE L TANK. TECHNICIAN USED AS PART REF A TEMPORARY REVISION IN THE IPC. FORMAT OF TEMPORARY REVISION WAS CONFUSING.

Narrative: THE INDICATOR ORIGINALLY INSTALLED ON THE ACFT; THE MANUFACTURER'S PART NUMBER OF WHICH CROSSED OVER TO COMPANY PART NUMBER (IND X) WAS RPTED AS HAVING A BLANKING INDICATION FOR THE L MAIN TANK ON THE 'A' CHANNEL. WHEN I CHKED STOCK ON THIS COMPANY PART NUMBER; IT SHOWED ZERO ON HAND AT THE STATION; AND ZERO SYS OWNERSHIP OF THE PART. THAT COMPANY WOULD NOT OWN A SINGLE UNIT OF A PART THAT WAS INSTALLED ON SOME NUMBER OF THEIR ACFT MADE NO SENSE TO ME; SO I REFERRED TO THE IPC FOR GUIDANCE. THE IPC CONTAINED A TEMPORARY REVISION; THE PURPOSE FOR WHICH IT STATED WAS TO CLARIFY THE PART NUMBERS FOR AIRPLANES. I FOUND THE TEMPORARY REVISION AS PRESENTED TO BE SOMEWHAT CONFUSING BECAUSE OF THE WAY IT WAS FORMATTED; AND DETERMINED THAT THE IND Y; WHICH THE TEMPORARY REVISION LISTED; MUST BE THE PROPER PART FOR THAT ACFT; BECAUSE THERE WAS A SUBSTANTIAL NUMBER OF 'DELETED' NOTATIONS ASSOCIATED WITH IND X AND OUR SUPPLY SYS SHOWED ZERO STOCK AND ZERO OWNERSHIP OF THAT PART NUMBER. TO CHK MYSELF; I RAN A MAINT OPS INQUIRY ON IND Y AND THAT SCREEN SHOWED THAT PART NUMBER AS COVERING EFFECTIVITIES. I BELIEVED THAT THIS WAS AN ACCEPTABLE XCHK THAT THE IND Y WAS THE PROPER PART FOR THIS AIRPLANE; EVEN AS I NOW ACKNOWLEDGE THAT I AM AWARE OF THE CAVEAT ON THE SUPPLY COMPUTER SCREEN ABOUT NOT USING THEM AS AN AUTHORITATIVE SOURCE. REVIEWED THE IPC; REALIZED MY READING ERROR. WILL HAVE ANOTHER MECH CHK MY REASONING PROCESS AND MANUAL INTERP WHEN WORKING ON ACFT IN FUTURE.

Data retrieved from NASA's ASRS site as of January 2009 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.