What was found
NUMBER TWO ENGINE COMPRESSOR STALLED IN FLIGHT. ENGINE RECOVERED AND CONTINUED OPERATING. *S/D* STALLS OCCURRED IN LIGHT RAIN AND MILD TURBULENCE AT FL400 WITH AUTO THROTTLES ON. ENGINE WAS REMOVED AND PRE-REPAIR RUN IN THE TEST CELL. ENGINE PASSED TEST WITH SIX DEGREES OF EGT MARGIN. HPC WAS DEEMED WEAK FROM TEST CELL DATA AND WAS TORN DOWN. TEAR DOWN INVESTIGATION OF THE HPC SHOWED NO SIGNS OF ABNORMAL WEAR OR DETERIORATION THAT WOULD HAVE CONTRIBUTED TO THE STALLS.