What was found
DURING CRUISE FLIGHT AT FL 380, THE AUTOPILOT B DISENGAGED. BOTH A AND B ENGAGE BUTTONS WERE PRESSED, HOWEVER NEITHER AUTOPILOT WOULD ENGAGE. THE MCP LED DISPLAYS WERE BLANK AND THE BACK LIGHTING WAS NOT ILLUMINATED. ADDITIONALLY THE VNAV AND LNAV SELECTOR BUTTON LIGHTS WERE FLICKERING. THIS CONDITION LASTED APPROXIMATELY 30 SECONDS. NORMAL INDICATIONS WERE RESTORED AND THE B AP WAS RE ENGAGED. GROUNDED - YES. REF B737-800 FIM 22-11 TASK 801 ACCOMPLISHED DFCS BITE TEST CURRENT STATUS CHECK OK. ON FLIGHT REVIEW A CHANNEL NO FAULTS. ON RELATED FLT LEG B CHANNEL LOGGED MCP FAULT 22-11607. PERFORMED FIM 22-11 TASK 803 MCP TEST NORMAL NO FAULTS LOGGED. NOTE ON FLIGHT REVIEW NO AUTO PILOT OR FLT DIRECTOR FAULTS LOGGED. NO HISTORY 30 DAYS.