What was found
THE NR 3 ENGINE EXPERIENCED COMPRESSOR STALLS WHILE ENROUTE. THE AIRCRAFT WAS RETURNED TO LGW. THE NR 3 ENGINE WAS REMOVED AND REPLACED. THE ENGINE WAS RUN AND OPERATION CHECKED GOOD. *S/D* INSPECTION OF THE ENGINE FOUND THAT THE ENTIRE COMPRESSOR HAD SUFFERED EXTENSIVE DAMAGE. IN ADDITION, ONE EACH STAGE 2 BOOSTER VANE HAD SUFFERED IMPACT DAMAGE. METALLURGICAL ANALYSIS CONFIRMED FOREIGN OBJECT DAMAGE. COMPRESSOR SURGES WERE A RESULT OF EXTENSIVE DAMAGE TO THE COMPRESSOR.