Narrative:

December 2011; maintenance engineering discovered that the flight control computer (FCC) operations software installed on aircraft X; a B737-800; was not effective for that airplane. A maintenance engineering request was written which asked to confirm the software part number and [to] load the correct software. Upon confirming that the loaded software was 'not effective'[for aircraft X]; I; technician X; initiated a log page write-up to load the correct software into the 'a' system flight control computer (FCC). Following maintenance manual (M/M) 22-11-33 and illustrated parts catalog (ipc) 22-11-33-03A; I loaded the correct software into the computer. I then performed the software installation test--also per MM 22-11-33--and the test results were normal. At this point; I had less than an hour remaining in my shift and asked oncoming technician Y to help me complete the job by calling ZZZ maintenance control to verify the software part number; as aircraft X is an ETOPS aircraft. The newly installed software was confirmed as 'effective' with ZZZ maintenance control. I checked the lower weather minimums maintenance practices section of the MM; saw the words 'FMS component/lru replacement' at the top of the checklist; and since I had not replaced the FCC; I assumed the lower minimums weather status of the airplane was not affected by the software load; so I signed-off the log page; gave it to the oncoming shift lead to enter [maintenance data base] and went home. January 2012; a maintenance engineer stopped me in the hallway and told me that they'd written a similar engineering request to check the software on aircraft Y; which was in the hangar that afternoon. I printed this engineering request and noticed that in addition to the steps outlined on the engineering request; I had worked the previous week; a third step had been added to the procedure: to accomplish additional lower weather minimums tests as required by the lower weather minimums maintenance checklist. At that point; it occurred to me that the software load may be a weather minimums maintenance procedures sensitive task. I read through the weather minimums maintenance practices in detail and discovered a paragraph on the last page which stated that software loading on a lower weather minimums sensitive line replaceable unit (lru) required that the additional minimums tests listed in the weather minimums maintenance checklist be performed. Upon discovering this; I telephoned ZZZ maintenance control and we had a lengthy discussion as to whether or not the software load was in fact a weather minimums sensitive maintenance [issue]. I pointed out the aforementioned paragraph and maintenance control then called ZZZ1 to downgrade the aircraft. The fact that the lower weather minimums maintenance checklist states: 'FMS component/lru replacement'; lead me to wrongly believe that additional tests were not required since I was not replacing the FCC; but merely loading software. A further contributing factor to my error was that I was performing the task at the end of my shift. Suggest replacing the word 'replacement' on the lower minimums maintenance checklist with the word 'replacement and software load' or simply 'maintenance.'

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Original NASA ASRS Text

Title: Two Technicians report about an additional Maintenance step added to an Engineering Request to perform a Lower Weather Minimums Maintenance Procedures Test per Maintenance Manual (M/M) 22-11-33; on B737-800 aircraft whenever a Flight Control Computer (FCC) System OPS software requires replacement or software loading.

Narrative: December 2011; Maintenance Engineering discovered that the Flight Control Computer (FCC) OPS software installed on Aircraft X; a B737-800; was not effective for that airplane. A Maintenance Engineering request was written which asked to confirm the software part number and [to] load the correct software. Upon confirming that the loaded software was 'not Effective'[for Aircraft X]; I; Technician X; initiated a log page write-up to load the correct software into the 'A' System Flight Control Computer (FCC). Following Maintenance Manual (M/M) 22-11-33 and Illustrated Parts Catalog (IPC) 22-11-33-03A; I loaded the correct software into the computer. I then performed the software installation test--also per MM 22-11-33--and the test results were normal. At this point; I had less than an hour remaining in my shift and asked oncoming Technician Y to help me complete the job by calling ZZZ Maintenance Control to verify the software part number; as Aircraft X is an ETOPS aircraft. The newly installed software was confirmed as 'Effective' with ZZZ Maintenance Control. I checked the Lower Weather Minimums Maintenance Practices section of the MM; saw the words 'FMS Component/LRU REPLACEMENT' at the top of the checklist; and since I had not replaced the FCC; I assumed the Lower Minimums Weather status of the airplane was not affected by the software load; so I signed-off the Log page; gave it to the oncoming Shift Lead to enter [Maintenance data base] and went home. January 2012; a Maintenance Engineer stopped me in the hallway and told me that they'd written a similar Engineering Request to check the software on Aircraft Y; which was in the hangar that afternoon. I printed this Engineering Request and noticed that in addition to the steps outlined on the Engineering Request; I had worked the previous week; a third step had been added to the procedure: to accomplish additional Lower Weather Minimums Tests as required by the Lower Weather Minimums Maintenance Checklist. At that point; it occurred to me that the software load may be a Weather Minimums Maintenance Procedures sensitive task. I read through the Weather Minimums Maintenance Practices in detail and discovered a paragraph on the last page which stated that software loading on a Lower Weather Minimums sensitive Line Replaceable Unit (LRU) required that the additional Minimums Tests listed in the Weather Minimums Maintenance Checklist be performed. Upon discovering this; I telephoned ZZZ Maintenance Control and we had a lengthy discussion as to whether or not the software load was in fact a Weather Minimums sensitive maintenance [issue]. I pointed out the aforementioned paragraph and Maintenance Control then called ZZZ1 to downgrade the aircraft. The fact that the Lower Weather Minimums Maintenance Checklist states: 'FMS Component/LRU REPLACEMENT'; lead me to wrongly believe that additional tests were not required since I was not REPLACING the FCC; but merely loading software. A further contributing factor to my error was that I was performing the task at the end of my shift. Suggest replacing the word 'REPLACEMENT' on the Lower Minimums Maintenance Checklist with the word 'REPLACEMENT and SOFTWARE LOAD' or simply 'MAINTENANCE.'

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.