UNCOMMANDED AUTOPLT DISCONNECT AT FL410 RESULTS IN ROLL AND ALT LOSS.

Narrative

IN CRUISE FLT AT FL410; ON AUTOPLT; APPROX 100 NM W OF HBU; A PAX CAME FORWARD TO ADVISE THAT THE CABIN PHONE WAS RINGING INCESSANTLY. I WAS THE PIC AND PF; SO I TOOK THE RADIO. THE SIC; PNF; DEALT WITH THE PAX AND THE PHONE ISSUE. ATC ISSUED A FREQ CHANGE. I ACKNOWLEDGED AND LOOKED DOWN TO ENTER THE NEW FREQ INTO THE HONEYWELL. WHEN I LOOKED UP; THE ACFT WAS ROLLING TOWARD 45 DEGS OF BANK AND THE ALT WAS DECREASING. I SMOOTHLY RECOVERED MY BANK AND PITCH TO RETURN THE ACFT TO PROPER COURSE AND ALT. I ADVISED ATC ON THE NEW FREQ THAT I WAS RETURNING TO FL410. ATC EVIDENCED NO AWARENESS OF ANY DEV -- EITHER ALT OR COURSE. I RE-ENGAGED THE AUTOPLT; WE RAN THE AUTOPLT MALFUNCTION CHKLIST; DISCOVERED THE ACFT WAS TRIMMED TO FAVOR A ROLL TO THE R. I RETRIMMED THE ACFT AND CONTINUED TO OUR DEST WITHOUT FURTHER INCIDENT. THE AUTOPLT SHUT DOWN WITH WARNING OR ANNUNCIATION EITHER AUDIO OR VISUAL. AS I WAS RECOVERING; I DID NOTICE THAT BOTH THE AUTOPLT AND YAW DAMPER FUNCTION LIGHTS WERE OUT; BUT THE AUDIO AND VISUAL ANNUNCIATORS FAILED TO SOUND. AT THE TIME OF THE EVENT; WE WERE ABOUT 5 KTS BELOW MMO YET WE DIDN'T REACH OR EXCEED THE RED LINE. WE DID RECEIVE AN AUDIO BANK WARNING AS THE RECOVERY WAS INITIATED. AFTER REACHING OUR DEST; WE GOT THE PAX ON THEIR WAY AND ADVISED THE COMPANY THROUGH THE ON-DUTY ASSISTANT CHIEF PLT. CONTRIBUTING FACTORS: SIC DISTR BY PAX AND CABIN EQUIP PROB. PIC FLYING AND DISTR FROM THE PFD BY ENTERING FREQ CHANGE JUST WHEN THE AUTOPLT SHUT OFF WITHOUT ANNUNCIATION.