As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
5509-EVV- ON APPROACH INTO STL, LEFT ENGINE RPM FLUX - SHUT DOWN ENGINE AS PRECAUTION. MAINTENANCE PERFORMED ENGINE OPERATIONAL CHECKS. INSTALLED HAND HELD TESTER NO FAULTS INDICATED. ENGINE OPS CHECK GOOD AT ALL POWER SETTINGS DURING ONE HOUR OF GROUND OPERATION.