Narrative:

Aircraft originated flight after hangar maintenance. Flight had air return; due to captain's airspeed abnormalities. I found the quick disconnect loose on #1 air data computer. I reconnected loose line and checked others for security. I then tested the #1 air data computer and pitot system per amm. I failed to recall our new maintenance procedures manual (mpm) section that requires a CAT III upgrade for any write-up or maintenance action that affects a CAT III system. I thought; that since the unit was not removed; a CAT III upgrade was not necessary. I feel that particular phrase should be emphasized more in our training. Aircraft was CAT III upgraded at a later date.

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Original NASA ASRS Text

Title: A Mechanic reports about a B737-300 Air Turnback after hanger Maintenance due to Captain's Airspeed abnormalities. Quick disconnect hose found loose on # 1 ADC. Mechanic was informed later he failed to upgrade the aircraft to a Category-III Status.

Narrative: Aircraft originated flight after Hangar Maintenance. Flight had Air Return; due to Captain's Airspeed abnormalities. I found the Quick Disconnect loose on #1 ADC. I reconnected loose line and checked others for security. I then tested the #1 ADC and Pitot System Per AMM. I failed to recall our new Maintenance Procedures Manual (MPM) section that requires a CAT III upgrade for any write-up or maintenance action that affects a CAT III system. I thought; that since the unit was not removed; a CAT III upgrade was not necessary. I feel that particular phrase should be emphasized more in our training. Aircraft was CAT III upgraded at a later date.

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.