As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING A SCHEDULED NR 1 ENGINE CHANGE, THE UPPER CORE COWL WAS FOUND WITH A1" PUNCTURE IN IT. INVESTIGATION REVEALED THAT THE CORE COWL WAS IN CONTACT WITH THE TOP OF THE OIL TANK LEVEL SENSOR ON THE REMOVED ENGINE. A NEW CORE COWL WAS INSTALLED ON THE NEW ENGINE.