What was found
ON FLIGHT 2980 THE CREW REPORTED THE BACKGROUND LIGHTING ON OVERHEAD PANELS CHANNEL A B AND APU FIRE PANELS ON CHANNEL C WERE OFF IN FLIGHT BUT LATER RETURNED, I E INTERMITTANT. THE AIRCRAFT WAS REMOVED FROM SERVICE. OPERATED LIGHTS SEVERAL TIMES, ADJUSTED UP AND DOWN, COULD NOT DUPLICATE, EMB 33-10-00. NO PARTS REMOVED OR REPLACED. THE AIRCRAFT WAS RETURNED TO SERVICE.