As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CHAMPION SPARK PLUG, PART NUMBER RHB32S, BATCH 2D05 FIVE (5) SPARK PLUGS WITH CRACKS. 400 HOURS OF OPERATING TIME ON THE SPARK PLUGS. THE CENTER ELECTRODE ON 2 SPARK PLUGS DEVELOPED CRACKS ON THE TIPS. THE WIRE ELECTRODE ON 2 OTHER SPARK PLUGS DEVELOPED A CRACK GOING LENGTHWISE ALONG THE WIRE. ONE SPARK PLUG HAD CRACKS ON BOTH, THE CENTER ELECTRODE AND WIRE.