Narrative:

Aircraft was coming in with both autoplt channels on MEL. Maintenance control had requested that we try to get one side working. I met the aircraft when it arrived. I had reviewed the history of the autoplt system before meeting the aircraft and had determined to concentrate on the 'B' system. I went into the flight deck and neither would engage. Dfcs bite did not help. I decided to try changing an integrated flight assembly unit since it is used by both system. After finding out bite doesn't test the unit; I removed the box and sprayed the pins on the rack and box itself. I reinstalled the box and went back into the flight deck. Both channels of the autoplt now worked normally. Due to the history of the 'a' system; I thought it best to leave 'a' system as an MEL item and clear the MEL on the 'B' system. I did the necessary paperwork and released the aircraft to the captain. About 2 hours later; I realized the integrated flight accessory unit was a hydraulic component. I immediately notified maintenance control so they could have the aircraft recertified to CAT III status.

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Original NASA ASRS Text

Title: A B737-300 WITH 'A' AND 'B' AUTOPLTS INOP WAS REPAIRED WITH AN ACCESSORY UNIT REPLACEMENT. TECHNICIAN FAILED TO ADVISE MAINT CTL OF THE REPAIR AND THE NECESSITY TO RECERTIFY CAT III STATUS OF ACFT.

Narrative: ACFT WAS COMING IN WITH BOTH AUTOPLT CHANNELS ON MEL. MAINT CTL HAD REQUESTED THAT WE TRY TO GET ONE SIDE WORKING. I MET THE ACFT WHEN IT ARRIVED. I HAD REVIEWED THE HISTORY OF THE AUTOPLT SYS BEFORE MEETING THE ACFT AND HAD DETERMINED TO CONCENTRATE ON THE 'B' SYS. I WENT INTO THE FLT DECK AND NEITHER WOULD ENGAGE. DFCS BITE DID NOT HELP. I DECIDED TO TRY CHANGING AN INTEGRATED FLT ASSEMBLY UNIT SINCE IT IS USED BY BOTH SYS. AFTER FINDING OUT BITE DOESN'T TEST THE UNIT; I REMOVED THE BOX AND SPRAYED THE PINS ON THE RACK AND BOX ITSELF. I REINSTALLED THE BOX AND WENT BACK INTO THE FLT DECK. BOTH CHANNELS OF THE AUTOPLT NOW WORKED NORMALLY. DUE TO THE HISTORY OF THE 'A' SYS; I THOUGHT IT BEST TO LEAVE 'A' SYS AS AN MEL ITEM AND CLR THE MEL ON THE 'B' SYS. I DID THE NECESSARY PAPERWORK AND RELEASED THE ACFT TO THE CAPT. ABOUT 2 HRS LATER; I REALIZED THE INTEGRATED FLT ACCESSORY UNIT WAS A HYD COMPONENT. I IMMEDIATELY NOTIFIED MAINT CTL SO THEY COULD HAVE THE ACFT RECERTIFIED TO CAT III STATUS.

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.