What was found
AT FL 340 EXPERIENCED NR 1 ENGINE VIBRATION, N1 ROLLED BACK TO 34%, N2 62% FF 690 LBS. EXECUTED ENG FIRE SEVERE DAMAGE CHECKLIST, FUEL DUMP ABOUT 3000 LBS, DECLARED EMERGENCY LANDING 18C. INSPECTED INTAKE AND EXHAUST. NO DEFECTS NOTED. BOROSCOPE INSPECTED NR 1 ENGINE PER W/C 72X3501, NO DEFECTS NOTED, ENGINE OK FOR SERVICE. AFTER BOROSCOPE FOUND LOOSE B-NUT ON CDP LINE AT COMPRESSOR CASE. PERFORMED BOROSCOPE INSPECTION OF NR 1 ENG PER W/C 72X3501. NO DEFECTS NOTED. HOOKED UP VIBE SENSOR AND TACH WIRE ON NR 1 ENG FOR VIBE RUN. PERFORMED VIBE SURVEY PER MD-10-10 AMM 72-00-00-51, INDICATIONS ARE LESS THAN 1.0 MILS AT 3400, 3200 AND 3000 RPM. ENGINE RAN PER JRH.