A line mechanic reports a B737-700 came in with a write-up about autopilot 'B' disengaging two secon...

Narrative:

Aircraft came in with autopilot 'B' writen up. Disengaged about two seconds after hitting approach switch. Troubleshot and needed localizer antenna switch relay. Called maintenance control and controller said to placard on MEL chapter XXX; [inop] approach switch; and downgrade to CAT 2. After checking history the next day someone stated that per MEL; aircraft should not have been downgraded to CAT 2. I called my supervisor and he said he would check with his boss the next day. He checked with the director and he pulled up the log page and said that I downgraded the aircraft correctly. The write-up was corrected with replacement of the antenna switch relay. I investigated further and found out per MEL XXX that the aircraft was downgraded incorrectly. Should not have been CAT 2; instead of CAT 2. I went by what maintenance control told me and he specified to downgrade to CAT 2. I tried to click on the category link in the MEL and it would not come up. I should have scrolled down all the way to the bottom of the MEL to check CAT status. There were numerous MEL's for the mode control panel (MCP) (autopilot) control switches once I looked at it. Never take the word of a controller; always check yourself.

Original NASA ASRS Text

Title: A Line Mechanic reports a B737-700 came in with a write-up about Autopilot 'B' disengaging two seconds after hitting Approach switch. Incorrect MEL and CAT downgrade applied for Mode Control Panel (MCP) control switches due to correct CAT status being at the bottom of the MEL item.

Narrative: Aircraft came in with Autopilot 'B' writen up. Disengaged about two seconds after hitting Approach switch. Troubleshot and needed Localizer Antenna switch relay. Called Maintenance Control and Controller said to placard on MEL Chapter XXX; [inop] approach switch; and downgrade to CAT 2. After checking history the next day someone stated that per MEL; aircraft should not have been downgraded to CAT 2. I called my Supervisor and he said he would check with his boss the next day. He checked with the Director and he pulled up the Log page and said that I downgraded the aircraft correctly. The write-up was corrected with replacement of the antenna switch relay. I investigated further and found out per MEL XXX that the aircraft was downgraded incorrectly. Should not have been CAT 2; instead of CAT 2. I went by what Maintenance Control told me and he specified to downgrade to CAT 2. I tried to click on the category link in the MEL and it would not come up. I should have scrolled down all the way to the bottom of the MEL to check CAT status. There were numerous MEL's for the Mode Control Panel (MCP) (Autopilot) control switches once I looked at it. Never take the word of a Controller; always check yourself.

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.

Attributes
ACN	876984
Time
Date	201002
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Light	Daylight
Aircraft 1
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	Parked
Component
Aircraft Component	Autoflight System
Person 1
Function	Technician
Qualification	Maintenance Avionics Maintenance Airframe Maintenance Powerplant
Experience	Maintenance Technician 20
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Procedural MEL Deviation - Procedural Published Material / Policy

A line mechanic reports a B737-700 came in with a write-up about autopilot 'B' disengaging two seconds after hitting approach switch. Incorrect MEL and CAT downgrade applied for mode control panel (MCP) control switches due to correct CAT status being at the bottom of the MEL item.