A B757-200 psu was replaced at xx abc for damage. At a later check the psu's were tested and xx-abc ...

Attributes
ACN	655249
Time
Date	200504
Place
Locale Reference	airport : zzz.airport
State Reference	US
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Flight Phase	ground : maintenance
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	maintenance : technician
ASRS Report	655249
Person 2
Affiliation	company : air carrier
Function	maintenance : technician oversight : supervisor
Events
Anomaly	aircraft equipment problem : critical maintenance problem : improper documentation maintenance problem : improper maintenance non adherence : published procedure non adherence : far
Independent Detector	other other : 3
Resolutory Action	none taken : detected after the fact
Consequence	other other
Factors
Maintenance	performance deficiency : testing performance deficiency : non compliance with legal requirements performance deficiency : logbook entry performance deficiency : inspection performance deficiency : installation
Supplementary
Problem Areas	Aircraft Chart Or Publication Maintenance Human Performance
Primary Problem	Maintenance Human Performance

Narrative:

I was tasked to clear a deferral from aircraft X. The write-up was: call button and chimes at xx-abc inoperative. Button is broken. I went to the aircraft to see the situation of what the problem was. I investigated that the psu had to be changed due that we do not replace the call button only. I returned to the shop with the part number of the psu in question and looked it up in the ipc manual. Checked effectivity and proceeded to order a new one. Ordered new psu and looked up and printed maintenance manual reference for right&I of psu and oxygen generators. Gathered tools for removal and proceeded to the aircraft for removal. Dropped psu from ceiling. Pulled circuit breakers and proceeded with removal of psu. Then proceeded the right&I of oxygen generators in new psu per maintenance manual. Proceeded with tests and then put aircraft back to confign. During the signoff of the deferral in the corrective action block; I used the MEL reference of 25-20-18 instead of the correct maintenance manual reference of 25-23-01-04. It is to my knowledge that I installed oxygen generators in psu; but during c-chk the psu was dropped from ceiling and the oxygen generators were missing. If the oxygen generator are missing from this psu; it was an inadvertent mistake that I could have made. This was not an intentional act.

Original NASA ASRS Text

Title: A B757-200 PSU WAS REPLACED AT XX ABC FOR DAMAGE. AT A LATER CHK THE PSU'S WERE TESTED AND XX-ABC OXYGEN CANISTERS WERE FOUND MISSING.

Narrative: I WAS TASKED TO CLR A DEFERRAL FROM ACFT X. THE WRITE-UP WAS: CALL BUTTON AND CHIMES AT XX-ABC INOP. BUTTON IS BROKEN. I WENT TO THE ACFT TO SEE THE SIT OF WHAT THE PROB WAS. I INVESTIGATED THAT THE PSU HAD TO BE CHANGED DUE THAT WE DO NOT REPLACE THE CALL BUTTON ONLY. I RETURNED TO THE SHOP WITH THE PART NUMBER OF THE PSU IN QUESTION AND LOOKED IT UP IN THE IPC MANUAL. CHKED EFFECTIVITY AND PROCEEDED TO ORDER A NEW ONE. ORDERED NEW PSU AND LOOKED UP AND PRINTED MAINT MANUAL REF FOR R&I OF PSU AND OXYGEN GENERATORS. GATHERED TOOLS FOR REMOVAL AND PROCEEDED TO THE ACFT FOR REMOVAL. DROPPED PSU FROM CEILING. PULLED CIRCUIT BREAKERS AND PROCEEDED WITH REMOVAL OF PSU. THEN PROCEEDED THE R&I OF OXYGEN GENERATORS IN NEW PSU PER MAINT MANUAL. PROCEEDED WITH TESTS AND THEN PUT ACFT BACK TO CONFIGN. DURING THE SIGNOFF OF THE DEFERRAL IN THE CORRECTIVE ACTION BLOCK; I USED THE MEL REF OF 25-20-18 INSTEAD OF THE CORRECT MAINT MANUAL REF OF 25-23-01-04. IT IS TO MY KNOWLEDGE THAT I INSTALLED OXYGEN GENERATORS IN PSU; BUT DURING C-CHK THE PSU WAS DROPPED FROM CEILING AND THE OXYGEN GENERATORS WERE MISSING. IF THE OXYGEN GENERATOR ARE MISSING FROM THIS PSU; IT WAS AN INADVERTENT MISTAKE THAT I COULD HAVE MADE. THIS WAS NOT AN INTENTIONAL ACT.

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.

A B757-200 psu was replaced at xx abc for damage. At a later check the psu's were tested and xx-abc oxygen canisters were found missing.