What was found
ON CLIMBOUT OF MIAMI AT 17,000 FEET F/O ARTIFICIAL HORIZON FAILED WITH ATTITUDE FLAG. RETURNED WITHOUT INCIDENT. ACCOMPLISHED OVERWEIGHT LANDING AT 273,000 LBS. WIRING CHECK ACCOMPLISHED IAW MM 34-2-2. REMOVED AND REPLACED 2 AMP C/B B10-58 AND NR 2 ADI AS PER MM 20-50-1 & 34-25-0, ALSO REMOVED AND REPLACED NR 2 INSTRUMENT AMPLIFIER. NR 2 HORIZON & COMPASS SYSTEM GROUND TEST NORMAL IAW MM 34-25-0 & 34-21-0. TEST FLIGHT FOUND NR 2 HORIZON SYSTEM OPERATING NORMAL. AIRCRAFT RETURNED TO SERVICE.